package com.spring.puzzle.class1.example1.application
//省略 import
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

package com.spring.puzzle.class1.example1.application
//省略 import
@RestController
public class HelloWorldController {
    @RequestMapping(path = "hi", method = RequestMethod.GET)
    public String hi(){
         return "helloworld";
    };
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
      @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
//省略非关键代码
}

public @interface ComponentScan {

/**
 * Base packages to scan for annotated components.
 * <p>{@link #value} is an alias for (and mutually exclusive with) this
 * attribute.
 * <p>Use {@link #basePackageClasses} for a type-safe alternative to
 * String-based package names.
 */
@AliasFor("value")
String[] basePackages() default {};
//省略其他非关键代码
}

@SpringBootApplication
@ComponentScan("com.spring.puzzle.class1.example1.controller")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

@Service
public class ServiceImpl {

    private String serviceName;

    public ServiceImpl(String serviceName){
        this.serviceName = serviceName;
    }

}

// Candidate constructors for autowiring?
Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR ||
      mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
   return autowireConstructor(beanName, mbd, ctors, args);
}

private Object instantiate(
      String beanName, RootBeanDefinition mbd, Constructor<?> constructorToUse, Object[] argsToUse)

argsHolder = createArgumentArray(beanName, mbd, resolvedValues, bw, paramTypes, paramNames,
      getUserDeclaredConstructor(candidate), autowiring, candidates.length == 1);

return this.beanFactory.resolveDependency(
      new DependencyDescriptor(param, true), beanName, autowiredBeanNames, typeConverter);

//这个bean装配给ServiceImpl的构造器参数“serviceName”
@Bean
public String serviceName(){
    return "MyServiceName";
}

@Service
public class ServiceImpl {
    private String serviceName;
    public ServiceImpl(String serviceName){
        this.serviceName = serviceName;
    }
    public ServiceImpl(String serviceName, String otherStringParameter){
        this.serviceName = serviceName;
    }
}

@Service
@Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
public class ServiceImpl {
}

@RestController
public class HelloWorldController {

    @Autowired
    private ServiceImpl serviceImpl;

    @RequestMapping(path = "hi", method = RequestMethod.GET)
    public String hi(){
         return "helloworld, service is : " + serviceImpl;
    };
}

protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
   Field field = (Field) this.member;
   Object value;
   //寻找“bean”
   if (this.cached) {
      value = resolvedCachedArgument(beanName, this.cachedFieldValue);
   }
   else {
     //省略其他非关键代码
     value = beanFactory.resolveDependency(desc, beanName, autowiredBeanNames, typeConverter);
   }
   if (value != null) {
      //将bean设置给成员字段
      ReflectionUtils.makeAccessible(field);
      field.set(bean, value);
   }
}

@RestController
public class HelloWorldController {

    @Autowired
    private ApplicationContext applicationContext;

    @RequestMapping(path = "hi", method = RequestMethod.GET)
    public String hi(){
         return "helloworld, service is : " + getServiceImpl();
    };
 
    public ServiceImpl getServiceImpl(){
        return applicationContext.getBean(ServiceImpl.class);
    }

}

@RestController
public class HelloWorldController {
 
    @RequestMapping(path = "hi", method = RequestMethod.GET)
    public String hi(){
         return "helloworld, service is : " + getServiceImpl();
    };

    @Lookup
    public ServiceImpl getServiceImpl(){
        return null;
    }  

}

private final BeanFactory owner;

public Object intercept(Object obj, Method method, Object[] args, MethodProxy mp) throws Throwable {
   LookupOverride lo = (LookupOverride) getBeanDefinition().getMethodOverrides().getOverride(method);
   Assert.state(lo != null, "LookupOverride not found");
   Object[] argsToUse = (args.length > 0 ? args : null);  // if no-arg, don't insist on args at all
   if (StringUtils.hasText(lo.getBeanName())) {
      return (argsToUse != null ? this.owner.getBean(lo.getBeanName(), argsToUse) :
            this.owner.getBean(lo.getBeanName()));
   }
   else {
      return (argsToUse != null ? this.owner.getBean(method.getReturnType(), argsToUse) :
            this.owner.getBean(method.getReturnType()));
   }
}

@Lookup
public ServiceImpl getServiceImpl(){
    //下面的日志会输出么？
    log.info("executing this method");
    return null;
}

@Override
public Object instantiate(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner) {
   // Don't override the class with CGLIB if no overrides.
   if (!bd.hasMethodOverrides()) {
      //
      return BeanUtils.instantiateClass(constructorToUse);
   }
   else {
      // Must generate CGLIB subclass.
      return instantiateWithMethodInjection(bd, beanName, owner);
   }
}

@RestController
@Slf4j
@Validated
public class StudentController {
    @Autowired
    DataService dataService;

    @RequestMapping(path = "students/{id}", method = RequestMethod.DELETE)
    public void deleteStudent(@PathVariable("id") @Range(min = 1,max = 100) int id){
        dataService.deleteStudent(id);
    };
}

public interface DataService {
    void deleteStudent(int id);
}

@Repository
@Slf4j
public class OracleDataService implements DataService{
    @Override
    public void deleteStudent(int id) {
        log.info("delete student info maintained by oracle");
    }
}

@Repository
@Slf4j
public class CassandraDataService implements DataService{
    @Override
    public void deleteStudent(int id) {
        log.info("delete student info maintained by cassandra");
    }
}

protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
      //省略非关键代码
      for (BeanPostProcessor bp : getBeanPostProcessors()) {
         if (bp instanceof InstantiationAwareBeanPostProcessor) {
            InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
            PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
          //省略非关键代码
         }
      }
   }   
}

InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);

@Override
protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
   Field field = (Field) this.member;
   Object value;
   //省略非关键代码
      try {
          DependencyDescriptor desc = new DependencyDescriptor(field, this.required);
         //寻找“依赖”，desc为"dataService"的DependencyDescriptor
         value = beanFactory.resolveDependency(desc, beanName, autowiredBeanNames, typeConverter);
      }
      
   }
   //省略非关键代码
   if (value != null) {
      ReflectionUtils.makeAccessible(field);
      //装配“依赖”
      field.set(bean, value);
   }
}

protected String determineAutowireCandidate(Map<String, Object> candidates, DependencyDescriptor descriptor) {
   Class<?> requiredType = descriptor.getDependencyType();
   String primaryCandidate = determinePrimaryCandidate(candidates, requiredType);
   if (primaryCandidate != null) {
      return primaryCandidate;
   }
   String priorityCandidate = determineHighestPriorityCandidate(candidates, requiredType);
   if (priorityCandidate != null) {
      return priorityCandidate;
   }
   // Fallback
   for (Map.Entry<String, Object> entry : candidates.entrySet()) {
      String candidateName = entry.getKey();
      Object beanInstance = entry.getValue();
      if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||
            matchesBeanName(candidateName, descriptor.getDependencyName())) {
         return candidateName;
      }
   }
   return null;
}

private boolean indicatesMultipleBeans(Class<?> type) {
   return (type.isArray() || (type.isInterface() &&
         (Collection.class.isAssignableFrom(type) || Map.class.isAssignableFrom(type))));
}

@Repository
@Primary
@Slf4j
public class OracleDataService implements DataService{
    //省略非关键代码
}

@Autowired
DataService oracleDataService;

@Autowired()
@Qualifier("cassandraDataService")
DataService dataService;

@Nullable
public Object doResolveDependency(DependencyDescriptor descriptor, @Nullable String beanName,
      @Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
      //省略其他非关键代码
      //寻找bean过程
      Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);
      if (matchingBeans.isEmpty()) {
         if (isRequired(descriptor)) {
            raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
         }
         return null;
      }
      //省略其他非关键代码
      if (matchingBeans.size() > 1) {
         //省略多个bean的决策过程，即案例1重点介绍内容
      } 
     //省略其他非关键代码
}

@Autowired
@Qualifier("CassandraDataService")
DataService dataService;

@Autowired
@Qualifier("sQLiteDataService")
DataService dataService;

raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);

@Override
public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
   if (definition instanceof AnnotatedBeanDefinition) {
      String beanName = determineBeanNameFromAnnotation((AnnotatedBeanDefinition) definition);
      if (StringUtils.hasText(beanName)) {
         // Explicit bean name found.
         return beanName;
      }
   }
   // Fallback: generate a unique default bean name.
   return buildDefaultBeanName(definition, registry);
}

protected String buildDefaultBeanName(BeanDefinition definition) {
   String beanClassName = definition.getBeanClassName();
   Assert.state(beanClassName != null, "No bean class name set");
   String shortClassName = ClassUtils.getShortName(beanClassName);
   return Introspector.decapitalize(shortClassName);
}

public static String decapitalize(String name) {
    if (name == null || name.length() == 0) {
        return name;
    }
    if (name.length() > 1 && Character.isUpperCase(name.charAt(1)) &&
                    Character.isUpperCase(name.charAt(0))){
        return name;
    }
    char chars[] = name.toCharArray();
    chars[0] = Character.toLowerCase(chars[0]);
    return new String(chars);
}

@Autowired
@Qualifier("cassandraDataService")
DataService dataService;

@Repository("CassandraDataService")
@Slf4j
public class CassandraDataService implements DataService {
  //省略实现
}

public class StudentController {
    @Repository
    public static class InnerClassDataService implements DataService{
        @Override
        public void deleteStudent(int id) {
          //空实现
        }
    }
    //省略其他非关键代码
 }

@Autowired
@Qualifier("innerClassDataService")
DataService innerClassDataService;

public static String getShortName(String className) {
   Assert.hasLength(className, "Class name must not be empty");
   int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR);
   int nameEndIndex = className.indexOf(CGLIB_CLASS_SEPARATOR);
   if (nameEndIndex == -1) {
      nameEndIndex = className.length();
   }
   String shortName = className.substring(lastDotIndex + 1, nameEndIndex);
   shortName = shortName.replace(INNER_CLASS_SEPARATOR, PACKAGE_SEPARATOR);
   return shortName;
}

@Autowired
@Qualifier("studentController.InnerClassDataService")
DataService innerClassDataService;

//方式1：属性命名为要装配的bean名称
@Autowired
DataService oracleDataService;

//方式2：使用@Qualifier直接引用
@Autowired
@Qualifier("oracleDataService")
DataService dataService;

public @interface Value {

   /**
    * The actual value expression &mdash; for example, <code>#{systemProperties.myProp}</code>.
    */
   String value();

}

@Value("#{student}")
private Student student;

@Bean
public Student student(){
    Student student = createStudent(1, "xie");
    return student;
}

//注册正常字符串
@Value("我是字符串")
private String text; 

//注入系统参数、环境变量或者配置文件中的值
@Value("${ip}")
private String ip

//注入其他Bean属性，其中student为bean的ID，name为其属性
@Value("#{student.name}")
private String name;

username=admin
password=pass

@RestController
@Slf4j
public class ValueTestController {
    @Value("${username}")
    private String username;
    @Value("${password}")
    private String password;
 
    @RequestMapping(path = "user", method = RequestMethod.GET)
    public String getUser(){
       return username + ":" + password;
    };
}

@Nullable
public Object doResolveDependency(DependencyDescriptor descriptor, @Nullable String beanName,
      @Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
    //省略其他非关键代码
    Class<?> type = descriptor.getDependencyType();
      //寻找@Value
      Object value = getAutowireCandidateResolver().getSuggestedValue(descriptor);
      if (value != null) {
         if (value instanceof String) {
            //解析Value值
            String strVal = resolveEmbeddedValue((String) value);
            BeanDefinition bd = (beanName != null && containsBean(beanName) ?
                  getMergedBeanDefinition(beanName) : null);
            value = evaluateBeanDefinitionString(strVal, bd);
         }
         
         //转化Value解析的结果到装配的类型
         TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter());
         try {
            return converter.convertIfNecessary(value, type, descriptor.getTypeDescriptor());
         }
         catch (UnsupportedOperationException ex) {
            //异常处理
         }
      }
    //省略其他非关键代码
  }

@Nullable
protected Object findValue(Annotation[] annotationsToSearch) {
   if (annotationsToSearch.length > 0) {  
      AnnotationAttributes attr = AnnotatedElementUtils.getMergedAnnotationAttributes(
            AnnotatedElementUtils.forAnnotations(annotationsToSearch), this.valueAnnotationType);
      //valueAnnotationType即为@Value
      if (attr != null) {
         return extractValue(attr);
      }
   }
   return null;
}

public class UUIDEditor extends PropertyEditorSupport {

   @Override
   public void setAsText(String text) throws IllegalArgumentException          {
      if (StringUtils.hasText(text)) {
         //转化操作
         setValue(UUID.fromString(text.trim()));
      }
      else {
         setValue(null);
      }
   }
   //省略其他非关代码
  
}

String strVal = resolveEmbeddedValue((String) value);

[ConfigurationPropertySourcesPropertySource {name='configurationProperties'}, 
StubPropertySource {name='servletConfigInitParams'}, ServletContextPropertySource {name='servletContextInitParams'}, PropertiesPropertySource {name='systemProperties'}, OriginAwareSystemEnvironmentPropertySource {name='systemEnvironment'}, RandomValuePropertySource {name='random'},
OriginTrackedMapPropertySource {name='applicationConfig: classpath:/application.properties]'},
MapPropertySource {name='devtools'}]

@Nullable
protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {
   if (this.propertySources != null) {
      for (PropertySource<?> propertySource : this.propertySources) {
         Object value = propertySource.getProperty(key);
         if (value != null) {
         //查到value即退出  
         return convertValueIfNecessary(value, targetValueType);
         }
      }
   }
 
   return null;
}

user.name=admin
user.password=pass

@Bean
public Student student1(){
    return createStudent(1, "xie");
}

@Bean
public Student student2(){
    return createStudent(2, "fang");
}

private Student createStudent(int id, String name) {
    Student student = new Student();
    student.setId(id);
    student.setName(name);
    return student;
}

@RestController
@Slf4j
public class StudentController {

    private List<Student> students;

    public StudentController(List<Student> students){
        this.students = students;
    }

    @RequestMapping(path = "students", method = RequestMethod.GET)
    public String listStudents(){
       return students.toString();
    };

}

@Bean
public List<Student> students(){
    Student student3 = createStudent(3, "liu");
    Student student4 = createStudent(4, "fu");
    return Arrays.asList(student3, student4);
}

private Object resolveMultipleBeans(DependencyDescriptor descriptor, @Nullable String beanName,
      @Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) {
   final Class<?> type = descriptor.getDependencyType();
   if (descriptor instanceof StreamDependencyDescriptor) {
      //装配stream
      return stream;
   }
   else if (type.isArray()) {
      //装配数组
      return result;
   }
   else if (Collection.class.isAssignableFrom(type) && type.isInterface()) {
      //装配集合
      //获取集合的元素类型
      Class<?> elementType = descriptor.getResolvableType().asCollection().resolveGeneric();
      if (elementType == null) {
         return null;
      }
      //根据元素类型查找所有的bean
      Map<String, Object> matchingBeans = findAutowireCandidates(beanName, elementType,
            new MultiElementDescriptor(descriptor));
      if (matchingBeans.isEmpty()) {
         return null;
      }
      if (autowiredBeanNames != null) {
         autowiredBeanNames.addAll(matchingBeans.keySet());
      }
      //转化查到的所有bean放置到集合并返回
      TypeConverter converter = (typeConverter != null ? typeConverter : getTypeConverter());
      Object result = converter.convertIfNecessary(matchingBeans.values(), type);
      //省略非关键代码
      return result;
   }
   else if (Map.class == type) {
      //解析map
      return matchingBeans;
   }
   else {
      return null;
   }
}

Object multipleBeans = resolveMultipleBeans(descriptor, beanName, autowiredBeanNames, typeConverter);
if (multipleBeans != null) {
   return multipleBeans;
}
Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);

@Bean
public List<Student> students(){
    Student student1 = createStudent(1, "xie");
    Student student2 = createStudent(2, "fang");
    Student student3 = createStudent(3, "liu");
    Student student4 = createStudent(4, "fu");
    return Arrays.asList(student1，student2，student3, student4);
}

@Bean
    public Student student1(){
        return createStudent(1, "xie");
    }
    @Bean
    public Student student2(){
        return createStudent(2, "fang");
    }
    @Bean
    public Student student3(){
        return createStudent(3, "liu");
    }
    @Bean
    public Student student4(){
        return createStudent(4, "fu");
    }

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class LightMgrService {
  @Autowired
  private LightService lightService;
  public LightMgrService() {
    lightService.check();
  }
}

@Service
public class LightService {
    public void start() {
        System.out.println("turn on all lights");
    }
    public void shutdown() {
        System.out.println("turn off all lights");
    }
    public void check() {
        System.out.println("check all lights");
    }
}

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
		throws BeanCreationException {
    //省略非关键代码
	if (instanceWrapper == null) {
		instanceWrapper = createBeanInstance(beanName, mbd, args);
	}
	final Object bean = instanceWrapper.getWrappedInstance();

    //省略非关键代码
    Object exposedObject = bean;
    try {
       populateBean(beanName, mbd, instanceWrapper);
       exposedObject = initializeBean(beanName, exposedObject, mbd);
    }
    catch (Throwable ex) {
    //省略非关键代码
}

public static <T> T instantiateClass(Constructor<T> ctor, Object... args) throws BeanInstantiationException {
   Assert.notNull(ctor, "Constructor must not be null");
   try {
      ReflectionUtils.makeAccessible(ctor);
      return (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isKotlinType(ctor.getDeclaringClass()) ?
            KotlinDelegate.instantiateClass(ctor, args) : ctor.newInstance(args));
   }
   catch (InstantiationException ex) {
      throw new BeanInstantiationException(ctor, "Is it an abstract class?", ex);
   }
   //省略非关键代码
}

@Component
public class LightMgrService {

    private LightService lightService;

    public LightMgrService(LightService lightService) {
        this.lightService = lightService;
        lightService.check();
    }
}

protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {
   //省略非关键代码 
   if (mbd == null || !mbd.isSynthetic()) {
      wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
   }
   try {
      invokeInitMethods(beanName, wrappedBean, mbd);
   }
   //省略非关键代码 
}

private LifecycleMetadata buildLifecycleMetadata(final Class<?> clazz) {
   //省略非关键代码 
   do {
      //省略非关键代码
      final List<LifecycleElement> currDestroyMethods = new ArrayList<>();
      ReflectionUtils.doWithLocalMethods(targetClass, method -> {
      //此处的 this.initAnnotationType 值，即为 PostConstruct.class
         if (this.initAnnotationType != null && method.isAnnotationPresent(this.initAnnotationType)) {
            LifecycleElement element = new LifecycleElement(method);
            currInitMethods.add(element);
  //非关键代码          
}

protected void invokeInitMethods(String beanName, final Object bean, @Nullable RootBeanDefinition mbd)
      throws Throwable {
   boolean isInitializingBean = (bean instanceof InitializingBean);
   if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
      // 省略非关键代码 
      else {
         ((InitializingBean) bean).afterPropertiesSet();
      }
   }
   // 省略非关键代码 
 }

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class LightMgrService {
  @Autowired
  private LightService lightService;
  
  @PostConstruct
  public void init() {
       lightService.check();
  }
}

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class LightMgrService implements InitializingBean {
    @Autowired
    private LightService lightService;
  
    @Override
    public void afterPropertiesSet() throws Exception {
        lightService.check();
    }
}

import org.springframework.stereotype.Service;
@Service
public class LightService {
  //省略其他非关键代码
  public void shutdown(){
    System.out.println("shutting down all lights");
  }
  //省略其他非关键代码
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class BeanConfiguration {
    @Bean
    public LightService getTransmission(){
        return new LightService();
    }
}

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class, args);
        context.close();
    }
}

private String inferDestroyMethodIfNecessary(Object bean, RootBeanDefinition beanDefinition) {
   String destroyMethodName = beanDefinition.getDestroyMethodName();
   if (AbstractBeanDefinition.INFER_METHOD.equals(destroyMethodName) ||(destroyMethodName == null && bean instanceof AutoCloseable)) {
      if (!(bean instanceof DisposableBean)) {
         try {
            //尝试查找 close 方法
            return bean.getClass().getMethod(CLOSE_METHOD_NAME).getName();
         }
         catch (NoSuchMethodException ex) {
            try {
               //尝试查找 shutdown 方法
               return bean.getClass().getMethod(SHUTDOWN_METHOD_NAME).getName();
            }
            catch (NoSuchMethodException ex2) {
               // no candidate destroy method found
            }
         }
      }
      return null;
   }
   return (StringUtils.hasLength(destroyMethodName) ? destroyMethodName : null);
}

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
      throws BeanCreationException {
   //省略非关键代码 
   if (instanceWrapper == null) {
      instanceWrapper = createBeanInstance(beanName, mbd, args);
   }
   //省略非关键代码
   // Initialize the bean instance.
   Object exposedObject = bean;
   try {
      populateBean(beanName, mbd, instanceWrapper);
      exposedObject = initializeBean(beanName, exposedObject, mbd);
   }
   //省略非关键代码 
   // Register bean as disposable.
   try {
      registerDisposableBeanIfNecessary(beanName, bean, mbd);
   }
   catch (BeanDefinitionValidationException ex) {
      throw new BeanCreationException(
            mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
   }

   return exposedObject;
}

public void registerDisposableBean(String beanName, DisposableBean bean) {
   //省略其他非关键代码
   synchronized (this.disposableBeans) {
      this.disposableBeans.put(beanName, bean);
   }
   //省略其他非关键代码
}

public void destroySingleton(String beanName) {
   // Remove a registered singleton of the given name, if any.
   removeSingleton(beanName);
   // Destroy the corresponding DisposableBean instance.
   DisposableBean disposableBean;
   synchronized (this.disposableBeans) {
      disposableBean = (DisposableBean) this.disposableBeans.remove(beanName);
   }
   destroyBean(beanName, disposableBean);
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class BeanConfiguration {
    @Bean(destroyMethod="")
    public LightService getTransmission(){
        return new LightService();
    }
}

protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) {
   AccessControlContext acc = (System.getSecurityManager() != null ? getAccessControlContext() : null);
   if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) {
      if (mbd.isSingleton()) {
         // Register a DisposableBean implementation that performs all destruction
         // work for the given bean: DestructionAwareBeanPostProcessors,
         // DisposableBean interface, custom destroy method.
         registerDisposableBean(beanName,
               new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
      }
      else {
        //省略非关键代码
      }
   }
}

public static boolean hasDestroyMethod(Object bean, RootBeanDefinition beanDefinition) {
   if (bean instanceof DisposableBean || bean instanceof AutoCloseable) {
      return true;
   }
   String destroyMethodName = beanDefinition.getDestroyMethodName();
   if (AbstractBeanDefinition.INFER_METHOD.equals(destroyMethodName)) {
      return (ClassUtils.hasMethod(bean.getClass(), CLOSE_METHOD_NAME) ||
            ClassUtils.hasMethod(bean.getClass(), SHUTDOWN_METHOD_NAME));
   }
   return StringUtils.hasLength(destroyMethodName);
}

public @interface Bean {
   //省略其他非关键代码
   String destroyMethod() default AbstractBeanDefinition.INFER_METHOD;
}

import org.springframework.stereotype.Component;
import java.io.Closeable;
@Service
public class LightService implements Closeable {
    public void close() {
        System.out.println("turn off all lights);
    }
    //省略非关键代码
}

@Service
public class ElectricService {

    public void charge() throws Exception {
        System.out.println("Electric charging ...");
        this.pay();
    }

    public void pay() throws Exception {
        System.out.println("Pay with alipay ...");
        Thread.sleep(1000);
    }

}

@Aspect
@Service
@Slf4j
public class AopConfig {
    @Around("execution(* com.spring.puzzle.class5.example1.ElectricService.pay()) ")
    public void recordPayPerformance(ProceedingJoinPoint joinPoint) throws Throwable {
        long start = System.currentTimeMillis();
        joinPoint.proceed();
        long end = System.currentTimeMillis();
        System.out.println("Pay method time cost（ms）: " + (end - start));
    }
}

@RestController
public class HelloWorldController {
    @Autowired
    ElectricService electricService;
    @RequestMapping(path = "charge", method = RequestMethod.GET)
    public void charge() throws Exception{
          electricService.charge();
    };
}

public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {
   if (bean != null) {
      Object cacheKey = getCacheKey(bean.getClass(), beanName);
      if (this.earlyProxyReferences.remove(cacheKey) != bean) {
         return wrapIfNecessary(bean, beanName, cacheKey);
      }
   }
   return bean;
}

protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
   // 省略非关键代码
   Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
   if (specificInterceptors != DO_NOT_PROXY) {
      this.advisedBeans.put(cacheKey, Boolean.TRUE);
      Object proxy = createProxy(
            bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
      this.proxyTypes.put(cacheKey, proxy.getClass());
      return proxy;
   }
   // 省略非关键代码 
}

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
      @Nullable Object[] specificInterceptors, TargetSource targetSource) {
  // 省略非关键代码
  ProxyFactory proxyFactory = new ProxyFactory();
  if (!proxyFactory.isProxyTargetClass()) {
   if (shouldProxyTargetClass(beanClass, beanName)) {
      proxyFactory.setProxyTargetClass(true);
   }
   else {
      evaluateProxyInterfaces(beanClass, proxyFactory);
   }
  }
  Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
  proxyFactory.addAdvisors(advisors);
  proxyFactory.setTargetSource(targetSource);
  customizeProxyFactory(proxyFactory);
   // 省略非关键代码
  return proxyFactory.getProxy(getProxyClassLoader());
}

@Service
public class ElectricService {
    @Autowired
    ElectricService electricService;
    public void charge() throws Exception {
        System.out.println("Electric charging ...");
        //this.pay();
        electricService.pay();
    }
    public void pay() throws Exception {
        System.out.println("Pay with alipay ...");
        Thread.sleep(1000);
    }
}

import org.springframework.aop.framework.AopContext;
import org.springframework.stereotype.Service;
@Service
public class ElectricService {
    public void charge() throws Exception {
        System.out.println("Electric charging ...");
        ElectricService electric = ((ElectricService) AopContext.currentProxy());
        electric.pay();
    }
    public void pay() throws Exception {
        System.out.println("Pay with alipay ...");
        Thread.sleep(1000);
    }
}

@SpringBootApplication
@EnableAspectJAutoProxy(exposeProxy = true)
public class Application {
    // 省略非关键代码
}

Electric charging ...
Pay with alipay ...
Pay method time cost(ms): 1005

public class User {
    private String payNum;
    public User(String payNum) {
        this.payNum = payNum;
    }
    public String getPayNum() {
        return payNum;
    }
    public void setPayNum(String payNum) {
        this.payNum = payNum;
    }
}

@Service
public class AdminUserService {
    public final User adminUser = new User("202101166");
    
    public void login() {
        System.out.println("admin user login...");
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class ElectricService {
    @Autowired
    private AdminUserService adminUserService;
    public void charge() throws Exception {
        System.out.println("Electric charging ...");
        this.pay();
    }

    public void pay() throws Exception {
        adminUserService.login();
        String payNum = adminUserService.adminUser.getPayNum();
        System.out.println("User pay num : " + payNum);
        System.out.println("Pay with alipay ...");
        Thread.sleep(1000);
    }
}

Electric charging ...
admin user login...
User pay num : 202101166
Pay with alipay ...

@Aspect
@Service
@Slf4j
public class AopConfig {
    @Before("execution(* com.spring.puzzle.class5.example2.AdminUserService.login(..)) ")
    public void logAdminLogin(JoinPoint pjp) throws Throwable {
        System.out.println("! admin login ...");
    }
}

public Object getProxy(ClassLoader classLoader) {
	return createAopProxy().getProxy(classLoader);
}

public Object getProxy(@Nullable ClassLoader classLoader) {
    // 省略非关键代码
    // 创建及配置 Enhancer
    Enhancer enhancer = createEnhancer();
    // 省略非关键代码
    // 获取Callback：包含DynamicAdvisedInterceptor，亦是MethodInterceptor
    Callback[] callbacks = getCallbacks(rootClass);
    // 省略非关键代码
    // 生成代理对象并创建代理（设置 enhancer 的 callback 值）
    return createProxyClassAndInstance(enhancer, callbacks);
    // 省略非关键代码
}

protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
   //创建代理类Class
   Class<?> proxyClass = enhancer.createClass();
   Object proxyInstance = null;
   //spring.objenesis.ignore默认为false
   //所以objenesis.isWorthTrying()一般为true
   if (objenesis.isWorthTrying()) {
      try {
         // 创建实例
         proxyInstance = objenesis.newInstance(proxyClass, enhancer.getUseCache());
      }
      catch (Throwable ex) {
          // 省略非关键代码
      }
   }
       
    if (proxyInstance == null) {
       // 尝试普通反射方式创建实例
       try {
          Constructor<?> ctor = (this.constructorArgs != null ?
                proxyClass.getDeclaredConstructor(this.constructorArgTypes) :
                proxyClass.getDeclaredConstructor());
          ReflectionUtils.makeAccessible(ctor);
          proxyInstance = (this.constructorArgs != null ?
                ctor.newInstance(this.constructorArgs) : ctor.newInstance());
      //省略非关键代码
       }
    }
   // 省略非关键代码
   ((Factory) proxyInstance).setCallbacks(callbacks);
   return proxyInstance;
}

public User getUser() {
    return user;
}

Electric charging ...
! admin login ...
admin user login...
User pay num : 202101166
Pay with alipay ...

protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
   Class<?> proxyClass = enhancer.createClass();
   Object proxyInstance = null;
   if (objenesis.isWorthTrying()) {
      try {
         proxyInstance = objenesis.newInstance(proxyClass, enhancer.getUseCache());
      }
   // 省略非关键代码
   ((Factory) proxyInstance).setCallbacks(callbacks);
   return proxyInstance;
}

public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
   // 省略非关键代码
    TargetSource targetSource = this.advised.getTargetSource();
    // 省略非关键代码 
      if (chain.isEmpty() && Modifier.isPublic(method.getModifiers())) {
         Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
         retVal = methodProxy.invoke(target, argsToUse);
      }
      else {
         // We need to create a method invocation...
         retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed();
      }
      retVal = processReturnType(proxy, target, method, retVal);
      return retVal;
   }
   //省略非关键代码
}

@Service
public class ElectricService {
    public void charge() throws Exception {
        System.out.println("Electric charging ...");
    }
}

//省略 imports
@Aspect
@Service
@Slf4j
public class AspectService {
  @Before("execution(* com.spring.puzzle.class6.example1.ElectricService.charge()) ")
  public void checkAuthority(JoinPoint pjp) throws Throwable {
      System.out.println("validating user authority");
      Thread.sleep(1000);
  }
}

validating user authority
Electric charging ...

//省略 imports
@Aspect
@Service
public class AopConfig {
    @Before("execution(* com.spring.puzzle.class6.example1.ElectricService.charge()) ")
    public void checkAuthority(JoinPoint pjp) throws Throwable {
        System.out.println("validating user authority");
        Thread.sleep(1000);
    }

    @Around("execution(* com.spring.puzzle.class6.example1.ElectricService.charge()) ")
    public void recordPerformance(ProceedingJoinPoint pjp) throws Throwable {
        long start = System.currentTimeMillis();
        pjp.proceed();
        long end = System.currentTimeMillis();
        System.out.println("charge method time cost: " + (end - start));
    }
}

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
      @Nullable Object[] specificInterceptors, TargetSource targetSource) {
   //省略非关键代码
   Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
   proxyFactory.addAdvisors(advisors);
   proxyFactory.setTargetSource(targetSource);
   //省略非关键代码
   return proxyFactory.getProxy(getProxyClassLoader());
}

@Override
@Nullable
protected Object[] getAdvicesAndAdvisorsForBean(
      Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) {
   List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
   if (advisors.isEmpty()) {
      return DO_NOT_PROXY;
   }
   return advisors.toArray();
  }

protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
   //寻找候选的 Advisor
   List<Advisor> candidateAdvisors = findCandidateAdvisors();
   //根据候选的 Advisor 和当前 bean 算出匹配的 Advisor
   List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
   extendAdvisors(eligibleAdvisors);
   if (!eligibleAdvisors.isEmpty()) {
      //排序
      eligibleAdvisors = sortAdvisors(eligibleAdvisors);
   }
   return eligibleAdvisors;
}

private List<Method> getAdvisorMethods(Class<?> aspectClass) {
   final List<Method> methods = new ArrayList<>();
   ReflectionUtils.doWithMethods(aspectClass, method -> {
      // Exclude pointcuts
      if (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) {
         methods.add(method);
      }
   }, ReflectionUtils.USER_DECLARED_METHODS);
   // 排序
   methods.sort(METHOD_COMPARATOR);
   return methods;
}

static {
   Comparator<Method> adviceKindComparator = new ConvertingComparator<>(
         new InstanceComparator<>(
               Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class),
         (Converter<Method, Annotation>) method -> {
            AspectJAnnotation<?> annotation =
               AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(method);
            return (annotation != null ? annotation.getAnnotation() : null);
         });
   Comparator<Method> methodNameComparator = new ConvertingComparator<>(Method::getName);
   //合并上面两者比较器
   METHOD_COMPARATOR = adviceKindComparator.thenComparing(methodNameComparator);
}

public int compare(S o1, S o2) {
   T c1 = this.converter.convert(o1);
   T c2 = this.converter.convert(o2);
   return this.comparator.compare(c1, c2);
}

(Converter<Method, Annotation>) method -> {
   AspectJAnnotation<?> annotation =
      AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(method);
   return (annotation != null ? annotation.getAnnotation() : null);
});

private static final Class<?>[] ASPECTJ_ANNOTATION_CLASSES = new Class<?>[] {
      Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class};

protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {
   for (Class<?> clazz : ASPECTJ_ANNOTATION_CLASSES) {
      AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);
      if (foundAnnotation != null) {
         return foundAnnotation;
      }
   }
   return null;
}

new InstanceComparator<>(
      Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class)

public InstanceComparator(Class<?>... instanceOrder) {
   Assert.notNull(instanceOrder, "'instanceOrder' array must not be null");
   this.instanceOrder = instanceOrder;
}

public int compare(T o1, T o2) {
   int i1 = getOrder(o1);
   int i2 = getOrder(o2);
   return (i1 < i2 ? -1 : (i1 == i2 ? 0 : 1));
}

private int getOrder(@Nullable T object) {
   if (object != null) {
      for (int i = 0; i < this.instanceOrder.length; i++) {
         //instance 在 instanceOrder 中的“排号”
         if (this.instanceOrder[i].isInstance(object)) {
            return i;
         }
      }
   }
   return this.instanceOrder.length;
}

@Service
public class ElectricService {
    @Autowired
    ElectricService electricService;
    public void charge() {
        electricService.doCharge();
    }
    public void doCharge() {
        System.out.println("Electric charging ...");
    }
}

//省略 imports
@Aspect
@Service
public class AopConfig {
    @Before("execution(* com.spring.puzzle.class6.example1.ElectricService.charge()) ")
    public void checkAuthority(JoinPoint pjp) throws Throwable {
        System.out.println("validating user authority");
        Thread.sleep(1000);
    }

    @Around("execution(* com.spring.puzzle.class6.example1.ElectricService.doCharge()) ")
    public void recordPerformance(ProceedingJoinPoint pjp) throws Throwable {
    long start = System.currentTimeMillis();
    pjp.proceed();
    long end = System.currentTimeMillis();
    System.out.println("charge method time cost: " + (end - start));
  }
}

import org.springframework.stereotype.Service;
@Service
public class ElectricService {
    public void charge() {
        System.out.println("Electric charging ...");
    }
}

//省略 imports
@Aspect
@Service
public class AopConfig {
  @Before("execution(* com.spring.puzzle.class5.example2.ElectricService.charge())")
  public void logBeforeMethod(JoinPoint pjp) throws Throwable {
      System.out.println("step into ->"+pjp.getSignature());
  }
  @Before("execution(* com.spring.puzzle.class5.example2.ElectricService.charge()) ")
  public void validateAuthority(JoinPoint pjp) throws Throwable {
      throw new RuntimeException("authority check failed");
  }
}

static {
   //第一个比较器，用来按照增强类型排序
   Comparator<Method> adviceKindComparator = new ConvertingComparator<>(
         new InstanceComparator<>(
               Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class),
         (Converter<Method, Annotation>) method -> {
            AspectJAnnotation<?> annotation =
               AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(method);
            return (annotation != null ? annotation.getAnnotation() : null);
         })
   //第二个比较器，用来按照方法名排序
   Comparator<Method> methodNameComparator = new ConvertingComparator<>(Method::getName);
   METHOD_COMPARATOR = adviceKindComparator.thenComparing(methodNameComparator);
}

public ConvertingComparator(Converter<S, T> converter) {
   this(Comparators.comparable(), converter);
}
// 省略非关键代码
public static <T> Comparator<T> comparable() {
   return ComparableComparator.INSTANCE;
}

public class ComparableComparator<T extends Comparable<T>> implements Comparator<T> {
 
   public static final ComparableComparator INSTANCE = new ComparableComparator();

   @Override
   public int compare(T o1, T o2) {
      return o1.compareTo(o2);
   }
}

public int compareTo(String anotherString) {
    int len1 = value.length;
    int len2 = anotherString.value.length;
    int lim = Math.min(len1, len2);
    char v1[] = value;
    char v2[] = anotherString.value;

    int k = 0;
    while (k < lim) {
        char c1 = v1[k];
        char c2 = v2[k];
        if (c1 != c2) {
            return c1 - c2;
        }
        k++;
    }
    return len1 - len2;
}

//省略 imports
@Aspect
@Service
public class AopConfig {
  @Before("execution(* com.spring.puzzle.class6.example2.ElectricService.charge())")
  public void logBeforeMethod(JoinPoint pjp) throws Throwable {
      System.out.println("step into ->"+pjp.getSignature());
  }
  @Before("execution(* com.spring.puzzle.class6.example2.ElectricService.charge()) ")
  public void checkAuthority(JoinPoint pjp) throws Throwable {
      throw new RuntimeException("authority check failed");
  }
}

@Slf4j
@Component
public class MyContextStartedEventListener implements ApplicationListener<ContextStartedEvent> {

  public void onApplicationEvent(final ContextStartedEvent event) {
    log.info("{} received: {}", this.toString(), event);
  }

}

@Override
public void start() {
   getLifecycleProcessor().start();
   publishEvent(new ContextStartedEvent(this));
}

public ConfigurableApplicationContext run(String... args) {
      //省略非关键代码
      context = createApplicationContext();
      //省略非关键代码
      prepareContext(context, environment, listeners, applicationArguments, printedBanner);
      refreshContext(context);
      //省略非关键代码 
      return context;
}

protected void refresh(ApplicationContext applicationContext) {
   Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext);
   ((AbstractApplicationContext) applicationContext).refresh();
}

@Component
public class MyContextRefreshedEventListener implements ApplicationListener<ContextRefreshedEvent> {

  public void onApplicationEvent(final ContextRefreshedEvent event) {
    log.info("{} received: {}", this.toString(), event);
  }

}

protected void finishRefresh() {
   //省略非关键代码
   initLifecycleProcessor();
   // Propagate refresh to lifecycle processor first.
   getLifecycleProcessor().onRefresh();
   // Publish the final event.
   publishEvent(new ContextRefreshedEvent(this));
   //省略非关键代码
}

@RestController
public class HelloWorldController {

    @Autowired
    private AbstractApplicationContext applicationContext;

    @RequestMapping(path = "publishEvent", method = RequestMethod.GET)
    public String notifyEvent(){
        applicationContext.start();       
        return "ok";
    };
}

private void startBeans(boolean autoStartupOnly) {
   Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans();
   Map<Integer, LifecycleGroup> phases = new HashMap<>();
   lifecycleBeans.forEach((beanName, bean) -> {
      if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {
         int phase = getPhase(bean);
         LifecycleGroup group = phases.get(phase);
         if (group == null) {
            group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);
            phases.put(phase, group);
         }
         group.add(beanName, bean);
      }
   });
   if (!phases.isEmpty()) {
      List<Integer> keys = new ArrayList<>(phases.keySet());
      Collections.sort(keys);
      for (Integer key : keys) {
         phases.get(key).start();
      }
   }
}

@Component
@Slf4j
public class MyLifeCycle implements Lifecycle {

    private volatile boolean running = false;

    @Override
    public void start() {
       log.info("lifecycle start");
       running = true;
    }

    @Override
    public void stop() {
       log.info("lifecycle stop");
       running = false;
    }

    @Override
    public boolean isRunning() {
        return running;
    }

}

@Slf4j
@Component
public class MyApplicationEnvironmentPreparedEventListener implements ApplicationListener<ApplicationEnvironmentPreparedEvent > {

    public void onApplicationEvent(final ApplicationEnvironmentPreparedEvent event) {
        log.info("{} received: {}", this.toString(), event);
    }

}

@Override
public void environmentPrepared(ConfigurableEnvironment environment) {
   this.initialMulticaster
         .multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));
}

public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
   //省略非关键代码
   private final SimpleApplicationEventMulticaster initialMulticaster;

   public EventPublishingRunListener(SpringApplication application, String[] args) {
      //省略非关键代码
      this.initialMulticaster = new SimpleApplicationEventMulticaster();
      for (ApplicationListener<?> listener : application.getListeners()) {
         this.initialMulticaster.addApplicationListener(listener);
      }
   }
 }

org.springframework.context.ApplicationListener=\
org.springframework.boot.ClearCachesApplicationListener,\
org.springframework.boot.builder.ParentContextCloserApplicationListener,\
org.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\
//省略其他监听器