spring4.1.8 扩展实战之二：Aware 接口揭秘

作者：程序员欣宸

2022 年 6 月 13 日
本文字数：12782 字
阅读完需：约 42 分钟

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这里分类和汇总了欣宸的全部原创(含配套源码)：https://github.com/zq2599/blog_demos

本篇概览

Aware.java 是个没有定义任何方法的接口，拥有众多子接口，在 spring 源码中有多处都在使用这些子接口完成各种场景下的回调操作，当业务有需要时，我们只需创建类来实现相关接口，再声明为 bean，就可以被 spring 容器主动回调；

spring 源码分析 Aware 子类的使用场景

接下来通过分析 spring 源码，我们来看看典型的 Aware 子类有哪些，使用场景是什么？
在 spring 容器初始化过程中，会执行 AbstractApplicationContext 类的 prepareBeanFactory 方法，这里面会创建一个 bean 后置处理器 ApplicationContextAwareProcessor，如下图红框所示：
在 bean 被初始化之前，所有的 bean 后置处理器的 postProcessBeforeInitialization 方法都会被执行，如下图红框所示：
由以上两步可以确定：对于每个 bean 后置处理器来说，它的 postProcessBeforeInitialization 方法会在每个 bean 的初始化之前被调用一次；
来看看 ApplicationContextAwareProcessor 类的 postProcessBeforeInitialization 方法，按照前面的分析，该方法在每个 bean 被初始化之前都会被执行，如下图红框所示，invokeAwareInterfaces 方法会被调用，这是我们要关注的重点：
展开 invokeAwareInterfaces 方法看看：

private void invokeAwareInterfaces(Object bean) {    if (bean instanceof Aware) {      if (bean instanceof EnvironmentAware) {        ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());      }      if (bean instanceof EmbeddedValueResolverAware) {        ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(            new EmbeddedValueResolver(this.applicationContext.getBeanFactory()));      }      if (bean instanceof ResourceLoaderAware) {        ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);      }      if (bean instanceof ApplicationEventPublisherAware) {        ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);      }      if (bean instanceof MessageSourceAware) {        ((MessageSourceAware) bean).setMessageSource(this.applicationContext);      }      if (bean instanceof ApplicationContextAware) {        ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);      }    }  }

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从上述代码可以看出，如果当前的 bean 实现了某个接口，那么它的某个对应的方法就会被调用，例如我们创建了一个 bean 实现了 ApplicationContextAware 接口，那么这个 bean 的 setApplicationContext 方法就会被调用，入参是 applicationContext 成员变量，这样我们的 bean 就能得到 applicationContext 对象了；
以上就是 Aware 的接口使用原理：业务按需要实现特定的 Aware 接口，spring 容器会主动找到该 bean，然后调用特定的方法，将特定的参数传递给 bean；

BeanNameAware 接口的调用场景

BeanNameAware 也是 Aware 的子接口，不过它的调用场景和前面分析的几个 Aware 子接口不同，并未出现在 ApplicationContextAwareProcessor 类的 invokeAwareInterfaces 方法中，我们来看看它是如何被调用的；
如下图所示，红框中就是 BeanNameAware 接口被调用的地方，而绿框中的 applyBeanPostProcessorsBeforeInitialization 方法就是前面我们分析的那些 Aware 子接口被调用的位置：
方法 invokeAwareMethods 如下所示，和前面的讨论一样，特定类型的 bean，其特定的方法被调用，传入特定的入参：

private void invokeAwareMethods(final String beanName, final Object bean) {    if (bean instanceof Aware) {      if (bean instanceof BeanNameAware) {        ((BeanNameAware) bean).setBeanName(beanName);      }      if (bean instanceof BeanClassLoaderAware) {        ((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());      }      if (bean instanceof BeanFactoryAware) {        ((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);      }    }  }

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实战，通过 Aware 接口得到想要的对象

了解 Aware 接口在 spring 环境中的用法之后，我们可以通过实战来验证前面所学了，本次实战我们创建两个类，分别实现 ApplicationContextAware 和 BeanNameAware 这两个接口，看声明的方法是否能被调用，并验证传入的对象是否有效（文章结尾处提供本次实战的工程源码下载）；
基于 maven 新建一个 SpringBoot 的 web 工程 customizeaware；
新建工具类 Utils，提供静态方法 printTrack 用于打印当前线程堆栈信息：

package com.bolingcavalry.customizeaware.util;

import org.slf4j.Logger;import org.slf4j.LoggerFactory;
/** * @Description : 提供一些常用的工具方法 * @Author : zq2599@gmail.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************************************************************");    }}

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新建类 CustomizeBeanNameAware，实现 BeanNameAware 接口，方法 setBeanName 被调用的时候会打印当前堆栈信息：

package com.bolingcavalry.customizeaware.aware;
import com.bolingcavalry.customizeaware.util.Utils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.BeanNameAware;import org.springframework.stereotype.Service;
/** * @Description : * @Author : zq2599@gmail.com * @Date : 2018-08-13 18:55 */@Servicepublic class CustomizeBeanNameAware implements BeanNameAware {    private String beanName;
    @Override    public void setBeanName(String beanName) {        Utils.printTrack("beanName is set to " + beanName);        this.beanName = beanName;    }
    public String getBeanName() {        return this.beanName;    }}

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新建类 CustomizeApplicationContextAware，实现 ApplicationContextAware 接口，方法 setApplicationContext 被调用的时候会打印当前堆栈信息：：

package com.bolingcavalry.customizeaware.aware;
import com.bolingcavalry.customizeaware.util.Utils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;import org.springframework.stereotype.Service;
/** * @Description : * @Author : zq2599@gmail.com * @Date : 2018-08-13 19:01 */@Servicepublic class CustomizeApplicationContextAware implements ApplicationContextAware {    private ApplicationContext applicationContext;
    @Override    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        Utils.printTrack("applicationContext is set to " + applicationContext);        this.applicationContext = applicationContext;    }
    public ApplicationContext getApplicationContext(){        return this.applicationContext;    }}

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新建一个 Controller，提供 http 服务用于验证 CustomizeBeanNameAware 和 CustomizeApplicationContextAware 这两个 bean，看看它们被 spring 容器设置的 beanName 和 applicationContext 是否可用：

package com.bolingcavalry.customizeaware.controller;
import com.bolingcavalry.customizeaware.aware.CustomizeApplicationContextAware;import com.bolingcavalry.customizeaware.aware.CustomizeBeanNameAware;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;
import java.util.Date;
/** * @Description : * @Author : zq2599@gmail.com * @Date : 2018-08-13 19:04 */@RestControllerpublic class HelloWorldController {
    @Autowired    private CustomizeBeanNameAware customizeBeanNameAware;
    @Autowired    private CustomizeApplicationContextAware customizeApplicationContextAware;
    @RequestMapping("/hello")    public String hello(){
        String[] beanDefinitionNames = customizeApplicationContextAware.getApplicationContext().getBeanDefinitionNames();
        StringBuilder stringBuilder = new StringBuilder();
        int arrayLength = 0;
        if(null!=beanDefinitionNames){            arrayLength = beanDefinitionNames.length;            //将所有bean的名称拼接成字符串（带html的换行符号<br>）            for(String name : beanDefinitionNames){                stringBuilder.append(name).append("<br>");            }        }
        return "hello, "                + new Date()                + "<br><br>CustomizeBeanNameAware instance bean name : "                + customizeBeanNameAware.getBeanName()                + "<br><br>bean definition names, size "                + arrayLength                + ", detail :<br><br>"                + stringBuilder;    }

}

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启动应用，看到启动日志中带有 CustomizeBeanNameAware 和 CustomizeApplicationContextAware 的接口方法被调用时输出的日志，并且线程堆栈和我们之前看的 spring 源码位置一致，分别是 ApplicationContextAwareProcessor.invokeAwareInterfaces()和 AbstractAutowireCapableBeanFactory.invokeAwareMethods()：

C:\jdk\bin\java.exe -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=63257 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Djava.rmi.server.hostname=localhost -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true -javaagent:C:\software\JetBrains\IntelliJIDEA\lib\idea_rt.jar=63258:C:\software\JetBrains\IntelliJIDEA\bin -Dfile.encoding=UTF-8 -classpath C:\jdk\jre\lib\charsets.jar;C:\jdk\jre\lib\deploy.jar;C:\jdk\jre\lib\ext\access-bridge-64.jar;C:\jdk\jre\lib\ext\cldrdata.jar;C:\jdk\jre\lib\ext\dnsns.jar;C:\jdk\jre\lib\ext\jaccess.jar;C:\jdk\jre\lib\ext\jfxrt.jar;C:\jdk\jre\lib\ext\localedata.jar;C:\jdk\jre\lib\ext\nashorn.jar;C:\jdk\jre\lib\ext\sunec.jar;C:\jdk\jre\lib\ext\sunjce_provider.jar;C:\jdk\jre\lib\ext\sunmscapi.jar;C:\jdk\jre\lib\ext\sunpkcs11.jar;C:\jdk\jre\lib\ext\zipfs.jar;C:\jdk\jre\lib\javaws.jar;C:\jdk\jre\lib\jce.jar;C:\jdk\jre\lib\jfr.jar;C:\jdk\jre\lib\jfxswt.jar;C:\jdk\jre\lib\jsse.jar;C:\jdk\jre\lib\management-agent.jar;C:\jdk\jre\lib\plugin.jar;C:\jdk\jre\lib\resources.jar;C:\jdk\jre\lib\rt.jar;D:\github\blog_demos\customizeaware\target\classes;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-starter-web\2.0.4.RELEASE\spring-boot-starter-web-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-starter\2.0.4.RELEASE\spring-boot-starter-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot\2.0.4.RELEASE\spring-boot-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-autoconfigure\2.0.4.RELEASE\spring-boot-autoconfigure-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-starter-logging\2.0.4.RELEASE\spring-boot-starter-logging-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;C:\Users\12167\.m2\repository\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;C:\Users\12167\.m2\repository\org\apache\logging\log4j\log4j-to-slf4j\2.10.0\log4j-to-slf4j-2.10.0.jar;C:\Users\12167\.m2\repository\org\apache\logging\log4j\log4j-api\2.10.0\log4j-api-2.10.0.jar;C:\Users\12167\.m2\repository\org\slf4j\jul-to-slf4j\1.7.25\jul-to-slf4j-1.7.25.jar;C:\Users\12167\.m2\repository\javax\annotation\javax.annotation-api\1.3.2\javax.annotation-api-1.3.2.jar;C:\Users\12167\.m2\repository\org\yaml\snakeyaml\1.19\snakeyaml-1.19.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-starter-json\2.0.4.RELEASE\spring-boot-starter-json-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\core\jackson-databind\2.9.6\jackson-databind-2.9.6.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\core\jackson-annotations\2.9.0\jackson-annotations-2.9.0.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\core\jackson-core\2.9.6\jackson-core-2.9.6.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.9.6\jackson-datatype-jdk8-2.9.6.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.9.6\jackson-datatype-jsr310-2.9.6.jar;C:\Users\12167\.m2\repository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.9.6\jackson-module-parameter-names-2.9.6.jar;C:\Users\12167\.m2\repository\org\springframework\boot\spring-boot-starter-tomcat\2.0.4.RELEASE\spring-boot-starter-tomcat-2.0.4.RELEASE.jar;C:\Users\12167\.m2\repository\org\apache\tomcat\embed\tomcat-embed-core\8.5.32\tomcat-embed-core-8.5.32.jar;C:\Users\12167\.m2\repository\org\apache\tomcat\embed\tomcat-embed-el\8.5.32\tomcat-embed-el-8.5.32.jar;C:\Users\12167\.m2\repository\org\apache\tomcat\embed\tomcat-embed-websocket\8.5.32\tomcat-embed-websocket-8.5.32.jar;C:\Users\12167\.m2\repository\org\hibernate\validator\hibernate-validator\6.0.11.Final\hibernate-validator-6.0.11.Final.jar;C:\Users\12167\.m2\repository\javax\validation\validation-api\2.0.1.Final\validation-api-2.0.1.Final.jar;C:\Users\12167\.m2\repository\org\jboss\logging\jboss-logging\3.3.2.Final\jboss-logging-3.3.2.Final.jar;C:\Users\12167\.m2\repository\com\fasterxml\classmate\1.3.4\classmate-1.3.4.jar;C:\Users\12167\.m2\repository\org\springframework\spring-web\5.0.8.RELEASE\spring-web-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-beans\5.0.8.RELEASE\spring-beans-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-webmvc\5.0.8.RELEASE\spring-webmvc-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-aop\5.0.8.RELEASE\spring-aop-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-context\5.0.8.RELEASE\spring-context-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-expression\5.0.8.RELEASE\spring-expression-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\slf4j\slf4j-api\1.7.25\slf4j-api-1.7.25.jar;C:\Users\12167\.m2\repository\org\springframework\spring-core\5.0.8.RELEASE\spring-core-5.0.8.RELEASE.jar;C:\Users\12167\.m2\repository\org\springframework\spring-jcl\5.0.8.RELEASE\spring-jcl-5.0.8.RELEASE.jar com.bolingcavalry.customizeaware.CustomizeawareApplication
  .   ____          _            __ _ _ /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/  ___)| |_)| | | | | || (_| |  ) ) ) )  '  |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot ::        (v2.0.4.RELEASE)
2018-08-14 06:07:11.512  INFO 18940 --- [           main] c.b.c.CustomizeawareApplication          : Starting CustomizeawareApplication on DESKTOP-82CCEBN with PID 18940 (D:\github\blog_demos\customizeaware\target\classes started by 12167 in D:\github\blog_demos\customizeaware)2018-08-14 06:07:11.514  INFO 18940 --- [           main] c.b.c.CustomizeawareApplication          : No active profile set, falling back to default profiles: default2018-08-14 06:07:11.546  INFO 18940 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6ab7a896: startup date [Tue Aug 14 06:07:11 GMT+08:00 2018]; root of context hierarchy2018-08-14 06:07:12.165  INFO 18940 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)2018-08-14 06:07:12.177  INFO 18940 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]2018-08-14 06:07:12.177  INFO 18940 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.322018-08-14 06:07:12.180  INFO 18940 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\jdk\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\iCLS\;C:\Program Files\Intel\Intel(R) Management Engine Components\iCLS\;C:\windows\system32;C:\windows;C:\windows\System32\Wbem;C:\windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\jdk\bin;C:\software\Git\cmd;C:\software\apache-maven-3.5.0\bin;;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;%SYSTEMROOT%\System32\OpenSSH\;C:\Users\12167\AppData\Local\Microsoft\WindowsApps;;.]2018-08-14 06:07:12.244  INFO 18940 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext2018-08-14 06:07:12.244  INFO 18940 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 700 ms2018-08-14 06:07:12.281  INFO 18940 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]2018-08-14 06:07:12.284  INFO 18940 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]2018-08-14 06:07:12.284  INFO 18940 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2018-08-14 06:07:12.284  INFO 18940 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]2018-08-14 06:07:12.285  INFO 18940 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]2018-08-14 06:07:12.305  INFO 18940 --- [           main] c.b.customizeaware.util.Utils            : applicationContext is set to org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6ab7a896: startup date [Tue Aug 14 06:07:11 GMT+08:00 2018]; root of context hierarchy************************************************************java.lang.Thread.getStackTrace() 1,559 <- com.bolingcavalry.customizeaware.util.Utils.printTrack() 20 <- com.bolingcavalry.customizeaware.aware.CustomizeApplicationContextAware.setApplicationContext() 22 <- org.springframework.context.support.ApplicationContextAwareProcessor.invokeAwareInterfaces() 120 <- org.springframework.context.support.ApplicationContextAwareProcessor.postProcessBeforeInitialization() 96 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization() 416 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean() 1,691 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 573 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 495 <- org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0() 317 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 222 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 315 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 199 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons() 759 <- org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization() 869 <- org.springframework.context.support.AbstractApplicationContext.refresh() 550 <- org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh() 140 <- org.springframework.boot.SpringApplication.refresh() 762 <- org.springframework.boot.SpringApplication.refreshContext() 398 <- org.springframework.boot.SpringApplication.run() 330 <- org.springframework.boot.SpringApplication.run() 1,258 <- org.springframework.boot.SpringApplication.run() 1,246 <- com.bolingcavalry.customizeaware.CustomizeawareApplication.main() 10************************************************************2018-08-14 06:07:12.307  INFO 18940 --- [           main] c.b.customizeaware.util.Utils            : beanName is set to customizeBeanNameAware************************************************************java.lang.Thread.getStackTrace() 1,559 <- com.bolingcavalry.customizeaware.util.Utils.printTrack() 20 <- com.bolingcavalry.customizeaware.aware.CustomizeBeanNameAware.setBeanName() 20 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods() 1,712 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean() 1,686 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean() 573 <- org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean() 495 <- org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0() 317 <- org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton() 222 <- org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean() 315 <- org.springframework.beans.factory.support.AbstractBeanFactory.getBean() 199 <- org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons() 759 <- org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization() 869 <- org.springframework.context.support.AbstractApplicationContext.refresh() 550 <- org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh() 140 <- org.springframework.boot.SpringApplication.refresh() 762 <- org.springframework.boot.SpringApplication.refreshContext() 398 <- org.springframework.boot.SpringApplication.run() 330 <- org.springframework.boot.SpringApplication.run() 1,258 <- org.springframework.boot.SpringApplication.run() 1,246 <- com.bolingcavalry.customizeaware.CustomizeawareApplication.main() 10************************************************************2018-08-14 06:07:12.359  INFO 18940 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-08-14 06:07:12.474  INFO 18940 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6ab7a896: startup date [Tue Aug 14 06:07:11 GMT+08:00 2018]; root of context hierarchy2018-08-14 06:07:12.507  INFO 18940 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String com.bolingcavalry.customizeaware.controller.HelloWorldController.hello()2018-08-14 06:07:12.511  INFO 18940 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)2018-08-14 06:07:12.511  INFO 18940 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)2018-08-14 06:07:12.524  INFO 18940 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-08-14 06:07:12.524  INFO 18940 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-08-14 06:07:12.602  INFO 18940 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup2018-08-14 06:07:12.622  INFO 18940 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''2018-08-14 06:07:12.625  INFO 18940 --- [           main] c.b.c.CustomizeawareApplication          : Started CustomizeawareApplication in 1.311 seconds (JVM running for 1.932)

复制代码

浏览器访问 web 服务，地址：http://localhost:8080/hello，如下图，两个实现了 Aware 接口的 bean 的被设置的信息都打印出来了，都是来自 spring 环境的内容：
验证结束，自定义的 Aware 接口实现类如果声明为 bean，在初始化的时候就会被 spring 容器按照接口类型找出来，通过调用接口方法的方式将特定的对象实例传递给 bean；

实战源码下载

本章实战的源码可以在 github 下载，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 customizeaware/下，如下图红框所示：
至此，spring 的 Aware 接口实战就结束了，由于篇幅所限，本章只选择了 BeanNameAware 和 ApplicationContextAware 这两个接口来实战，您可以结合 spring 源码去分析其他 Aware 接口的用处，再在 demo 用去验证它们；