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spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

程序员文章站 2022-03-09 08:18:42
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本章是《spring4.1.8扩展实战》系列的第六篇,目标是学习如何通过自己写代码的方式,向spring容器中注册bean;

原文地址:https://blog.csdn.net/boling_cavalry/article/details/82193692

关于注册bean到容器

我们开发的类,如果想注册到spring容器,让spring来完成实例化,常用方式如下:
1. xml中通过bean节点来配置;
2. 使用@Service、@Controller、@Conponent等注解;
其实,除了以上方式,spring还支持我们通过代码来将指定的类注册到spring容器中,也就是今天我们要实践的主要内容,接下来就从spring源码开始,先学习源码再动手实战;

本章概要

本章由以下几部分组成:
1. 了解BeanDefinitionRegistryPostProcessor接口;
2. 分析spring容器如何使用BeanDefinitionRegistryPostProcessor接口;
3. 实战,开发BeanDefinitionRegistryPostProcessor接口的实现类,验证通过代码注册bean的功能;

了解BeanDefinitionRegistryPostProcessor接口

实现注册bean功能的关键是BeanDefinitionRegistryPostProcessor接口,来看看这接口的继承关系,如下图:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

BeanDefinitionRegistryPostProcessor继承了BeanFactoryPostProcessor接口,关于BeanFactoryPostProcessor我们在上一章《spring4.1.8扩展实战之五:改变bean的定义(BeanFactoryPostProcessor接口)》已做了详细的分析和实战,知道BeanFactoryPostProcessor的实现类在其postProcessBeanFactory方法被调用时,可以对bean的定义进行控制,因此BeanDefinitionRegistryPostProcessor的实现类一共要实现以下两个方法:
1. void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException:
该方法的实现中,主要用来对bean定义做一些改变,这些在上一章《spring4.1.8扩展实战之五:改变bean的定义(BeanFactoryPostProcessor接口)》有详细说明;

2. void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException:
该方法用来注册更多的bean到spring容器中,详细观察入参BeanDefinitionRegistry接口,看看这个参数能带给我们什么能力:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)
从上图可以看到,为了能让我们通过代码将bean注册到spring环境,BeanDefinitionRegistry提供了丰富的方法来操作bean定义,判断、注册、反注册等方法都准备好了,我们在编写postProcessBeanDefinitionRegistry方法的内容时,就能直接使用入参registry的这些方法来完成判断和注册、反注册等操作;

分析spring容器如何使用BeanDefinitionRegistryPostProcessor接口

来看看BeanDefinitionRegistryPostProcessor接口的实现类,是在哪里被spring容器使用的:
1. 如下图所示,红框中的invokeBeanFactoryPostProcessors方法用来找出所有beanFactory后置处理器,并且调用这些处理器来改变bean的定义:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

2. 打开invokeBeanFactoryPostProcessors方法,如下所示,实际操作是委托PostProcessorRegistrationDelegate去完成的:

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
        PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
    }


3. 继续看PostProcessorRegistrationDelegate类的invokeBeanFactoryPostProcessors方法,该方法内容太丰富,我们只看重点,第一个重点如下图红框所示,当前的beanFactory是否实现了接口BeanDefinitionRegistry
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

为了搞清楚这个问题,我们应该看看当前beanFactory的继承和实现,以springboot中的应用为例,当前beanFactory的类型是DefaultListableBeanFactory,来看看它的类图:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)
从上图红框可见,beanFactory实现了BeanDefinitionRegistry接口,因此我们的关注点是if条件满足后的执行逻辑;
4. 继续看PostProcessorRegistrationDelegate类的invokeBeanFactoryPostProcessors方法,以下片段就是操作BeanDefinitionRegistryPostProcessor的核心逻辑:

boolean reiterate = true;
while (reiterate) {
    reiterate = false;
    //查出所有实现了BeanDefinitionRegistryPostProcessor接口的bean名称
    postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
    for (String ppName : postProcessorNames) {
        //前面的逻辑中,已经对实现了PriorityOrdered和Ordered的bean都处理过了,因此通过processedBeans过滤,processedBeans中没有的才会在此处理
        if (!processedBeans.contains(ppName)) {
            //根据名称和类型获取bean
            BeanDefinitionRegistryPostProcessor pp = beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class);
            //把已经调用过postProcessBeanDefinitionRegistry方法的bean全部放在registryPostProcessors中
            registryPostProcessors.add(pp);
            //把已经调用过postProcessBeanDefinitionRegistry方法的bean的名称全部放在processedBeans中
            processedBeans.add(ppName);
            //执行此bean的postProcessBeanDefinitionRegistry方法
            pp.postProcessBeanDefinitionRegistry(registry);
            //改变退出while的条件
            reiterate = true;
        }
    }
}

//registryPostProcessors中保存了所有执行过postProcessBeanDefinitionRegistry方法的bean,
//现在再来执行这些bean的postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(registryPostProcessors, beanFactory);
//regularPostProcessors中保存的是所有入参中带来的BeanFactoryPostProcessor实现类,并且这里面已经剔除了BeanDefinitionRegistryPostProcessor的实现类,现在要让这些bean执行postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);

如上述代码所示,所有实现了BeanDefinitionRegistryPostProcessor接口的bean,其postProcessBeanDefinitionRegistry方法都会调用,然后再调用其postProcessBeanFactory方法,这样一来,我们如果自定义了BeanDefinitionRegistryPostProcessor接口的实现类,那么我们开发的postProcessBeanDefinitionRegistry和postProcessBeanFactory方法都会被执行一次;

到这里,我们的源码学习部分就完成了,接下来看开始实战吧;

实战,开发BeanDefinitionRegistryPostProcessor接口的实现类

本次实战的内容是创建一个springboot工程,在里面自定义一个BeanDefinitionRegistryPostProcessor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:

名称 链接 备注
项目主页 https://github.com/zq2599/blog_demos 该项目在GitHub上的主页
git仓库地址(https) https://github.com/zq2599/blog_demos.git 该项目源码的仓库地址,https协议
git仓库地址(ssh) aaa@qq.com:zq2599/blog_demos.git 该项目源码的仓库地址,ssh协议

这个git项目中有多个文件夹,本章源码在文件夹customizebeandefinitionregistrypostprocessor下,如下图红框所示:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

接下来开始实战吧:
1. 基于maven创建一个springboot的web工程,名为customizebeandefinitionregistrypostprocessor,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>customizebeandefinitionregistrypostprocessor</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>customizebeandefinitionregistrypostprocessor</name>
    <description>Demo project for customize BeanDefinitionRegistryPostProcessor</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>


2. 定义一个服务接口CalculateService:

package com.bolingcavalry.customizebeandefinitionregistrypostprocessor.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();
}


3. 创建CalculateService接口的实现类CalculateServiceImpl,注意,不要将其声明为spring的bean

package com.bolingcavalry.customizebeandefinitionregistrypostprocessor.service.impl;

import com.bolingcavalry.customizebeandefinitionregistrypostprocessor.service.CalculateService;

public class CalculateServiceImpl implements CalculateService {

    private String desc = "desc from class";

    public void setDesc(String desc) {
        this.desc = desc;
    }


    @Override
    public int add(int a, int b) {
        return a + b;
    }

    @Override
    public String getServiceDesc() {
        return desc;
    }
}


4. 创建工具类Utils,里面是些工具方法,例如在日志中打印出当前线程的执行堆栈:

package com.bolingcavalry.customizebeandefinitionregistrypostprocessor.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @Description : 提供一些常用的工具方法
 * @Author : aaa@qq.com
 * @Date : 2018-08-14 05:51
 */
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************************************************************");
    }
}


5. 创建Controller类,用于验证我们通过代码注册的bean,注意要给成员变量calculateService添加注解@Autowired(required = false),否则有的IDEAL上会有红叉提示

package com.bolingcavalry.customizebeandefinitionregistrypostprocessor.controller;

import com.bolingcavalry.customizebeandefinitionregistrypostprocessor.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;

@RestController
public 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() + "]";
    }
}


6. 创建BeanDefinitionRegistryPostProcessor的实现类CustomizeBeanDefinitionRegistryPostProcessor:

@Component
public class CustomizeBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
    //打印当前堆栈信息    
        Utils.printTrack("execute postProcessBeanDefinitionRegistry");

    //创建一个bean的定义类的对象,bean类型是CalculateServiceImpl
        RootBeanDefinition helloBean = new RootBeanDefinition(CalculateServiceImpl.class);

        //bean的定义注册到spring环境
        beanDefinitionRegistry.registerBeanDefinition("calculateService", helloBean);
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
    //打印当前堆栈信息        
        Utils.printTrack("execute postProcessBeanFactory");
    }
}

上面CustomizeBeanDefinitionRegistryPostProcessor就是我们扩展出来的BeanDefinitionRegistryPostProcessor实现类,用来将CalculateServiceImpl注册到spring容器,名称为calculateService;

7. 启动类CustomizebeandefinitionregistrypostprocessorApplication:

package com.bolingcavalry.customizebeandefinitionregistrypostprocessor;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class CustomizebeandefinitionregistrypostprocessorApplication {

    public static void main(String[] args) {
        SpringApplication.run(CustomizebeandefinitionregistrypostprocessorApplication.class, args);
    }
}


8. 启动应用,在启动日志中可以看到CustomizeBeanDefinitionRegistryPostProcessor的方法被调用时的堆栈情况:

2018-08-30 18:55:40.323  INFO 14880 --- [           main] c.b.c.util.Utils                         : execute postProcessBeanDefinitionRegistry
************************************************************
java.lang.Thread.getStackTrace() 1,556 <- 
com.bolingcavalry.customizebeandefinitionregistrypostprocessor.util.Utils.printTrack() 20 <- 
com.bolingcavalry.customizebeandefinitionregistrypostprocessor.registrypostprocessor.CustomizeBeanDefinitionRegistryPostProcessor.postProcessBeanDefinitionRegistry() 21 <- 
org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors() 272 <- 
org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors() 122 <- 
org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors() 687 <- 
org.springframework.context.support.AbstractApplicationContext.refresh() 525 <- 
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.customizebeandefinitionregistrypostprocessor.CustomizebeandefinitionregistrypostprocessorApplication.main() 10
************************************************************
2018-08-30 18:55:40.542  INFO 14880 --- [           main] c.b.c.util.Utils                         : execute postProcessBeanFactory
************************************************************
java.lang.Thread.getStackTrace() 1,556 <- 
com.bolingcavalry.customizebeandefinitionregistrypostprocessor.util.Utils.printTrack() 20 <- 
com.bolingcavalry.customizebeandefinitionregistrypostprocessor.registrypostprocessor.CustomizeBeanDefinitionRegistryPostProcessor.postProcessBeanFactory() 31 <- 
org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors() 283 <- 
org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors() 127 <- 
org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors() 687 <- 
org.springframework.context.support.AbstractApplicationContext.refresh() 525 <- 
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.customizebeandefinitionregistrypostprocessor.CustomizebeandefinitionregistrypostprocessorApplication.main() 10
************************************************************


9. 在浏览器输入:http://localhost:8080/add/1/2,如下图可以看到网页正常响应,controller可以正常使用calculateService实例:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

10. 去掉CustomizeBeanDefinitionRegistryPostProcessor的注释@Component,重启应用,再去访问http://localhost:8080/add/1/2,可以看到网页提示错误如下图:
spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)

11. 看后台日志,是因为calculateService这个bean为空,导致HelloController在响应请求的时候出现了空指针异常,这也再次证明了CustomizeBeanDefinitionRegistryPostProcessor的注册操作是有效的:

2018-08-30 19:00:01.186 ERROR 2760 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
    at com.bolingcavalry.customizebeandefinitionregistrypostprocessor.controller.HelloController.add(HelloController.java:18) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_111]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_111]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_111]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_111]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.18.RELEASE.jar:4.3.18.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:800) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1471) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_111]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_111]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]

至此,自定义bean注册的实战就结束了,其实除了注册bean,我们还能利用BeanDefinitionRegistry这个入参做些其他事情,例如查找bean,反注册bean等,帮助我们实现一些bean操作的业务需求;

《spring4.1.8扩展实战》系列文章链接:
1. 《spring4.1.8扩展实战之一:自定义环境变量验证》;
2. 《spring4.1.8扩展实战之二:Aware接口揭秘》;
3. 《spring4.1.8扩展实战之三:广播与监听》;
4. 《spring4.1.8扩展实战之四:感知spring容器变化(SmartLifecycle接口)》;
5. 《spring4.1.8扩展实战之五:改变bean的定义(BeanFactoryPostProcessor接口)》;
6. 《spring4.1.8扩展实战之六:注册bean到spring容器(BeanDefinitionRegistryPostProcessor接口)》;
7. 《spring4.1.8扩展实战之七:控制bean(BeanPostProcessor接口)》;

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