spring4.1.8 扩展实战之七：控制 bean(BeanPostProcessor 接口)

作者：程序员欣宸

2022 年 6 月 18 日
本文字数：14121 字
阅读完需：约 46 分钟

spring4.1.8扩展实战之七：控制bean(BeanPostProcessor接口)

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本章是《spring4.1.8 扩展实战》的第七篇，我们来尝试在容器初始化的时候对 bean 实例做设置；

控制 bean 的两种扩展方式

两种方式可以对 bean 做控制（例如修改某个成员变量）

改变 bean 的定义(BeanFactoryPostProcessor 接口) ，可以想象成修改了 class 文件，这样实例化出来的每个对象都变了；
只改变实例化的对象(BeanPostProcessor 接口)；

上述两种方式都能控制 bean，第一种请参照《spring4.1.8扩展实战之五：改变bean的定义(BeanFactoryPostProcessor接口)》，今天我们来研究第二种：改变实例化的对象；

本章概览

全文由以下部分组成：

spring 源码分析，了解 BeanPostProcessor 接口的实现类如何被注册到 spring 容器；
spring 源码分析，了解已经注册到 spring 环境的 BeanPostProcessor 实现类如何被使用；
实战，开发一个 BeanPostProcessor 实现类，验证是否能用来改变指定的 bean；

源码分析：BeanPostProcessor 接口的实现类如何被注册到 spring 容器

从 spring 容器的初始化代码看起吧，看 AbstractApplicationContext 类的 refresh 方法，如下图所示，红框中的方法负责将 BeanPostProcessor 接口的实现类注册到 spring 容器：

展开 registerBeanPostProcessors 方法，发现是委托 PostProcessorRegistrationDelegate 类的静态方法 registerBeanPostProcessors 来完成注册工作的：

protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {  PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);}

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展开 PostProcessorRegistrationDelegate.registerBeanPostProcessors 方法，里面的代码逻辑简洁整齐，意图目的一目了然：

public static void registerBeanPostProcessors(    ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {  //获取所有实现BeanPostProcessor接口的bean的名称  String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
  //注意，此时尽管注册操作还没有开始，但是之前已经有一些特殊的bean已经注册进来了，  //详情请看AbstractApplicationContext类的prepareBeanFactory方法，  //因此getBeanPostProcessorCount()方法返回的数量并不为零，  //加一是因为方法末尾会注册一个ApplicationListenerDetector接口的实现类  int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;  //这里的BeanPostProcessorChecker也是个BeanPostProcessor的实现类，用于每个bean的初始化完成后，做一些简单的检查  beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
  //如果这些bean还实现了PriorityOrdered接口（在意执行顺序），就全部放入集合priorityOrderedPostProcessors   List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();  //集合internalPostProcessors，用来存放同时实现了PriorityOrdered和MergedBeanDefinitionPostProcessor接口的bean  List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();  //集合orderedPostProcessorNames用来存放实现了Ordered接口的bean的名称（在意执行顺序）  List<String> orderedPostProcessorNames = new ArrayList<String>();  //集合nonOrderedPostProcessorNames用来存放即没实现PriorityOrdered接口，也没有实现Ordered接口的bean的名称（不关心执行顺序）  List<String> nonOrderedPostProcessorNames = new ArrayList<String>();  for (String ppName : postProcessorNames) {    if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {      BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);      //实现了PriorityOrdered接口的bean，都放入集合priorityOrderedPostProcessors      priorityOrderedPostProcessors.add(pp);      if (pp instanceof MergedBeanDefinitionPostProcessor) {        //实现了MergedBeanDefinitionPostProcessor接口的bean，都放入internalPostProcessors集合        internalPostProcessors.add(pp);      }    }    else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {      //实现了Ordered接口的bean，将其名称都放入orderedPostProcessorNames集合      orderedPostProcessorNames.add(ppName);    }    else {      //既没实现PriorityOrdered接口，也没有实现Ordered接口的bean，将其名称放入nonOrderedPostProcessorNames集合      nonOrderedPostProcessorNames.add(ppName);    }  }
  //实现了PriorityOrdered接口的bean排序  OrderComparator.sort(priorityOrderedPostProcessors);  //注册到容器  registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
  List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();  //处理所有实现了Ordered接口的bean  for (String ppName : orderedPostProcessorNames) {    BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);    orderedPostProcessors.add(pp);    //前面将所有实现了PriorityOrdered和MergedBeanDefinitionPostProcessor的bean放入internalPostProcessors，    //此处将所有实现了Ordered和MergedBeanDefinitionPostProcessor的bean放入internalPostProcessors    if (pp instanceof MergedBeanDefinitionPostProcessor) {      internalPostProcessors.add(pp);    }  }
  //实现了Ordered接口的bean排序  OrderComparator.sort(orderedPostProcessors);  //注册到容器  registerBeanPostProcessors(beanFactory, orderedPostProcessors);
  List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();  for (String ppName : nonOrderedPostProcessorNames) {    BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);    nonOrderedPostProcessors.add(pp);    //此处将其余实现了MergedBeanDefinitionPostProcessor的bean放入internalPostProcessors    if (pp instanceof MergedBeanDefinitionPostProcessor) {      internalPostProcessors.add(pp);    }  }  //注册到容器  registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
  OrderComparator.sort(internalPostProcessors);  //将所有实现了MergedBeanDefinitionPostProcessor接口的bean也注册到容器  registerBeanPostProcessors(beanFactory, internalPostProcessors);  //创建一个ApplicationListenerDetector对象并且注册到容器，这就是前面计算beanProcessorTargetCount的值时加一的原因  beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));}

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以上代码已加注释，就不多解读了，有一点需要注意：对于实现了 MergedBeanDefinitionPostProcessor 接口的 bean，在前面几次调用 registerBeanPostProcessors 方法的时候已经注册过了，那么在最后执行的==registerBeanPostProcessors(beanFactory, internalPostProcessors)==，岂不是将一个 bean 注册了多次？
为了弄清楚这个问题需要看 registerBeanPostProcessors 方法：

private static void registerBeanPostProcessors(    ConfigurableListableBeanFactory beanFactory, List<BeanPostProcessor> postProcessors) {
  for (BeanPostProcessor postProcessor : postProcessors) {    //对每个bean都调用beanFactory.addBeanPostProcessor方法来注册    beanFactory.addBeanPostProcessor(postProcessor);  }}

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addBeanPostProcessor 方法的代码在 AbstractApplicationContext 类中，如下所示，==先删除再添加，这样反复注册也没有问题==：

@Overridepublic void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {  Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");  //如果已经注册，就先删除掉  this.beanPostProcessors.remove(beanPostProcessor);  //再注册  this.beanPostProcessors.add(beanPostProcessor);  if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {    this.hasInstantiationAwareBeanPostProcessors = true;  }  if (beanPostProcessor instanceof DestructionAwareBeanPostProcessor) {    this.hasDestructionAwareBeanPostProcessors = true;  }}

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至此，我们已经弄清楚了 BeanPostProcessor 实现类的 bean 注册到 spring 容器的逻辑，接下来看看 spring 容器如何使用这些 bean；

源码分析，BeanPostProcessor 实现类如何被使用

要弄清楚 BeanPostProcessor 接口的实现类是在哪里被用到的，还是从负责容器初始化的 AbstractApplicationContext 类的 refresh 方法看起，如下图红框中的 finishBeanFactoryInitialization 方法，就是负责实例化和初始化 bean 的：

从 finishBeanFactoryInitialization 方法到 BeanPostProcessor 的实现类被使用，中间有多层逻辑和调用，篇幅所限就不逐个展开了，直接列出堆栈信息，您可以根据此信息去查看对应源码：

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean()org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean()org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean()org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject()org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton()org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean()org.springframework.beans.factory.support.AbstractBeanFactory.getBean()org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons()org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization()org.springframework.context.support.AbstractApplicationContext.refresh()org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh()org.springframework.boot.SpringApplication.refresh()org.springframework.boot.SpringApplication.refreshContext()org.springframework.boot.SpringApplication.run()org.springframework.boot.SpringApplication.run()org.springframework.boot.SpringApplication.run()

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根据上述堆栈信息，直接查看 AbstractAutowireCapableBeanFactory 类的 initializeBean()方法：

protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {  if (System.getSecurityManager() != null) {    AccessController.doPrivileged(new PrivilegedAction<Object>() {      @Override      public Object run() {        invokeAwareMethods(beanName, bean);        return null;      }    }, getAccessControlContext());  }  else {    invokeAwareMethods(beanName, bean);  }
  Object wrappedBean = bean;  if (mbd == null || !mbd.isSynthetic()) {    //对已经实例化的bean，在初始化前用BeanPostProcessor实现类去处理    wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);  }
  try {    //bean的初始化    invokeInitMethods(beanName, wrappedBean, mbd);  }  catch (Throwable ex) {    throw new BeanCreationException(        (mbd != null ? mbd.getResourceDescription() : null),        beanName, "Invocation of init method failed", ex);  }
  if (mbd == null || !mbd.isSynthetic()) {    //对已经实例化的bean，在初始化后用BeanPostProcessor实现类去处理    wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);  }  return wrappedBean;}

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如上所示，我们最关注的代码是==applyBeanPostProcessorsBeforeInitialization==和==applyBeanPostProcessorsAfterInitialization==这两个方法，它们分别在 bean 的初始化方法==invokeInitMethods==的前后被执行；
先看看 applyBeanPostProcessorsBeforeInitialization 方法，逻辑非常简单，就是取出所有已注册的 BeanPostProcessor 实现类，执行其 postProcessBeforeInitialization 方法，入参是当前正在做实例化和初始化的 bean 实例：

@Overridepublic Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)    throws BeansException {
  Object result = existingBean;  //逐一执行每个BeanPostProcessor实现类的postProcessBeforeInitialization方法  for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {    result = beanProcessor.postProcessBeforeInitialization(result, beanName);    if (result == null) {      return result;    }  }  return result;}

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在 invokeInitMethods 方法执行完毕后会执行 applyBeanPostProcessorsAfterInitialization 方法，代码如下，与 applyBeanPostProcessorsBeforeInitialization 如出一辙，仅有的不同是调用的 beanProcessor 的方法变成了 postProcessAfterInitialization：

@Overridepublic Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)    throws BeansException {
  Object result = existingBean;  //逐一执行每个BeanPostProcessor实现类的postProcessAfterInitialization方法  for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {    result = beanProcessor.postProcessAfterInitialization(result, beanName);    if (result == null) {      return result;    }  }  return result;}

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以上就是 spring 容器初始化过程中对 BeanPostProcessor 实现类的使用场景，此时还剩一点疑问需要澄清：==在分析注册过程的时候，曾看到实现 MergedBeanDefinitionPostProcessor 接口的 bean 是最后注册的，那么这些 MergedBeanDefinitionPostProcessor 实现类在 spring 容器中是何处使用的呢？==
为了搞清这个问题，来看看 AbstractAutowireCapableBeanFactory 类的 doCreateBean 方法，前面我们分析的 initializeBean 方法就是在这里面被调用的：

如上图所示，红框中就是用所有 MergedBeanDefinitionPostProcessor 实现类去处理当前正在实例化的 bean，然后才会执行绿框中的 initializeBean 方法（里面是我们刚才分析的 bean 的初始化，BeanPostProcessor 实现类被使用的逻辑）；
来看看红框中的 applyMergedBeanDefinitionPostProcessors 方法，主要目的是处理特殊的合成 bean 的定义类：

protected void applyMergedBeanDefinitionPostProcessors(RootBeanDefinition mbd, Class<?> beanType, String beanName)      throws BeansException {
  try {    //取出每个注册的BeanPostProcessor实现类    for (BeanPostProcessor bp : getBeanPostProcessors()) {      //只有实现了MergedBeanDefinitionPostProcessor接口才执行      if (bp instanceof MergedBeanDefinitionPostProcessor) {        MergedBeanDefinitionPostProcessor bdp = (MergedBeanDefinitionPostProcessor) bp;        //执行postProcessMergedBeanDefinition        bdp.postProcessMergedBeanDefinition(mbd, beanType, beanName);      }    }  }  catch (Exception ex) {    throw new BeanCreationException(mbd.getResourceDescription(), beanName,        "Post-processing failed of bean type [" + beanType + "] failed", ex);  }}

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至此，我们对 BeanPostProcessor 有关的源码分析就完成了，小结一下：

初始化时，spring 容器有特别处理，会直接调用 beanFactory.addBeanPostProcessor 进行注册（例如 AbstractApplicationContext 类的 prepareBeanFactory 方法中就有）；
找出所有实现了 BeanPostProcessor 接口的 bean，注册到容器，注册顺序如下：第一：实现了 PriorityOrdered 接口的，排序后；第二：实现了 Ordered 接口的，排序后；第三：既没实现 PriorityOrdered 接口，也没有实现 Ordered 接口的；第四：实现了 MergedBeanDefinitionPostProcessor 接口的（这些也按照 PriorityOrdered、Ordered 等逻辑拍过续）；第五：实例化一个 ApplicationListenerDetector 对象；
实例化 bean 的时候，对于每个 bean，先用 MergedBeanDefinitionPostProcessor 实现类的 postProcessMergedBeanDefinition 方法处理每个 bean 的定义类；
再用 BeanPostProcessor 的 postProcessBeforeInitialization 方法处理每个 bean 实例；
bean 实例初始化；
用 BeanPostProcessor 的 postProcessAfterInitialization 方法处理每个 bean 实例；

源码分析结束，接下来自定义一个 BeanPostProcessor 实现类，验证我们之前的分析：控制 bean 实例；

实战自定义 BeanPostProcessor 实现类

本次实战的内容是创建一个 springboot 工程，在里面自定义一个 BeanPostProcessor 接口的实现类，如果您不想敲代码，也可以去 github 下载源码，地址和链接信息如下表所示：

这个 git 项目中有多个文件夹，本章源码在文件夹 customizebeanpostprocessor 下，如下图红框所示：

接下来开始实战吧：
基于 maven 创建一个 springboot 的 web 工程，名为 customizebeanpostprocessor，pom.xml 如下：

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>
    <groupId>com.bolingcavalry</groupId>    <artifactId>customizebeanpostprocessor</artifactId>    <version>0.0.1-SNAPSHOT</version>    <packaging>jar</packaging>
    <name>customizebeanpostprocessor</name>    <description>Demo project for Spring Boot</description>
    <parent>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-parent</artifactId>        <version>1.5.15.RELEASE</version>        <relativePath/> <!-- lookup parent from repository -->    </parent>
    <properties>        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>        <java.version>1.8</java.version>    </properties>
    <dependencies>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>        </dependency>
        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-test</artifactId>            <scope>test</scope>        </dependency>    </dependencies>
    <build>        <plugins>            <plugin>                <groupId>org.springframework.boot</groupId>                <artifactId>spring-boot-maven-plugin</artifactId>            </plugin>        </plugins>    </build></project>

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创建 Utils.java，里面有一些静态的工具方法，例如打印当前堆栈：

package com.bolingcavalry.customizebeanpostprocessor.util;
import org.slf4j.Logger;import org.slf4j.LoggerFactory;
public class Utils {
    private static final Logger logger = LoggerFactory.getLogger(Utils.class);
    /**     * 打印当前线程堆栈信息     * @param prefix     */    public static void printTrack(String prefix){        StackTraceElement[] st = Thread.currentThread().getStackTrace();
        if(null==st){            logger.info("invalid stack");            return;        }
        StringBuffer sbf =new StringBuffer();
        for(StackTraceElement e:st){            if(sbf.length()>0){                sbf.append(" <- ");                sbf.append(System.getProperty("line.separator"));            }
            sbf.append(java.text.MessageFormat.format("{0}.{1}() {2}"                    ,e.getClassName()                    ,e.getMethodName()                    ,e.getLineNumber()));        }
        logger.info(prefix                + "\n************************************************************\n"                + sbf.toString()                + "\n************************************************************");    }}

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创建接口 CalculateService，定义了几个方法：

package com.bolingcavalry.customizebeanpostprocessor.service;
public interface CalculateService {    /**     * 整数加法     * @param a     * @param b     * @return     */    int add(int a, int b);
    /**     * 返回当前实现类的描述信息     * @return     */    String getServiceDesc();
    /**     * 设置当前实现类的描述信息     * @return     */    void setServiceDesc(String serviceDesc);}

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创建 CalculateService 的实现类 CalculateServiceImpl，并且用 @Service 注解将定义为 spring 的 bean：

package com.bolingcavalry.customizebeanpostprocessor.service.impl;

import com.bolingcavalry.customizebeanpostprocessor.service.CalculateService;import org.springframework.stereotype.Service;
@Service("calculateService")public class CalculateServiceImpl implements CalculateService {
    private String serviceDesc = "desc from class";
    @Override    public int add(int a, int b) {        return a + b;    }
    @Override    public String getServiceDesc() {        return serviceDesc;    }
    @Override    public void setServiceDesc(String serviceDesc) {        this.serviceDesc = serviceDesc;    }}

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注意该类的成员变量 serviceDesc，值已经固定为"desc from class"；
创建 Controller 类 HelloController，在响应 web 请求的时候，会用到 calculateService 提供的服务：

package com.bolingcavalry.customizebeanpostprocessor.controller;
import com.bolingcavalry.customizebeanpostprocessor.service.CalculateService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;
@RestControllerpublic class HelloController {
    @Autowired(required = false)    CalculateService calculateService;

    @GetMapping("/add/{a}/{b}")    public String add(@PathVariable("a") int a, @PathVariable("b") int b){        return "add result : " + calculateService.add(a, b) + ", from [" + calculateService.getServiceDesc() + "]";    }}

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如上所示，正常情况下，web 响应为"add result : x， from [desc from class]"，这个==desc from class==，就是 CalculateServiceImpl 的成员变量 serviceDesc 的值；
创建 BeanPostProcessor 的实现类 CustomizeBeanPostProcessor，这里面会修改 calculateService 实例的成员变量 serviceDesc 的值，记得用注解 @Component 将其设置为 bean：

package com.bolingcavalry.customizebeanpostprocessor.processor;
import com.bolingcavalry.customizebeanpostprocessor.service.CalculateService;import com.bolingcavalry.customizebeanpostprocessor.util.Utils;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;import org.springframework.stereotype.Component;
@Componentpublic class CustomizeBeanPostProcessor implements BeanPostProcessor {    @Override    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {        if("calculateService".equals(beanName)) {      //打印当前堆栈            Utils.printTrack("do postProcess before initialization");            CalculateService calculateService = (CalculateService)bean;            //修改calculateService实例的成员变量serviceDesc的值            calculateService.setServiceDesc("desc from " + this.getClass().getSimpleName());        }        return bean;    }
    @Override    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {        if("calculateService".equals(beanName)) {            //打印当前堆栈            Utils.printTrack("do postProcess after initialization");        }        return bean;    }}

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启动应用，在启动日志中可以看到 CustomizeBeanPostProcessor 实例的两个方法被调用时打印的堆栈日志，和之前我们分析的源码是一致的：

2018-09-02 18:35:53.618  INFO 22520 --- [           main] c.b.c.util.Utils                         : do postProcess before initialization************************************************************java.lang.Thread.getStackTrace() 1,559 <- com.bolingcavalry.customizebeanpostprocessor.util.Utils.printTrack() 15 <- com.bolingcavalry.customizebeanpostprocessor.processor.CustomizeBeanPostProcessor.postProcessBeforeInitialization() 14 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization() 409 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean() 1,626 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 555 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 483 <- org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject() 312 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 230 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 308 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 202 <- org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate() 208 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency() 1,138 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency() 1,066 <- org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject() 585 <- org.springframework.beans.factory.annotation.InjectionMetadata.inject() 88 <- org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues() 366 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean() 1,272 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 553 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 483 <- org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject() 312 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 230 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 308 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 197 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons() 761 <- org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization() 867 <- org.springframework.context.support.AbstractApplicationContext.refresh() 543 <- org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh() 122 <- org.springframework.boot.SpringApplication.refresh() 693 <- org.springframework.boot.SpringApplication.refreshContext() 360 <- org.springframework.boot.SpringApplication.run() 303 <- org.springframework.boot.SpringApplication.run() 1,118 <- org.springframework.boot.SpringApplication.run() 1,107 <- com.bolingcavalry.customizebeanpostprocessor.CustomizebeanpostprocessorApplication.main() 10************************************************************2018-09-02 18:35:53.619  INFO 22520 --- [           main] c.b.c.util.Utils                         : do postProcess after initialization************************************************************java.lang.Thread.getStackTrace() 1,559 <- com.bolingcavalry.customizebeanpostprocessor.util.Utils.printTrack() 15 <- com.bolingcavalry.customizebeanpostprocessor.processor.CustomizeBeanPostProcessor.postProcessAfterInitialization() 24 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization() 423 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean() 1,638 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 555 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 483 <- org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject() 312 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 230 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 308 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 202 <- org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate() 208 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency() 1,138 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency() 1,066 <- org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject() 585 <- org.springframework.beans.factory.annotation.InjectionMetadata.inject() 88 <- org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues() 366 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean() 1,272 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 553 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 483 <- org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject() 312 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 230 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 308 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 197 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons() 761 <- org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization() 867 <- org.springframework.context.support.AbstractApplicationContext.refresh() 543 <- org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh() 122 <- org.springframework.boot.SpringApplication.refresh() 693 <- org.springframework.boot.SpringApplication.refreshContext() 360 <- org.springframework.boot.SpringApplication.run() 303 <- org.springframework.boot.SpringApplication.run() 1,118 <- org.springframework.boot.SpringApplication.run() 1,107 <- com.bolingcavalry.customizebeanpostprocessor.CustomizebeanpostprocessorApplication.main() 10************************************************************

复制代码

在浏览器访问地址：http://localhost:8080/add/1/2，可以看到响应如下图所示，calculateService 的成员变量 serviceDesc 的值已经被 CustomizeBeanPostProcessor 改为==desc from CustomizeBeanPostProcessor==：