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【SpringBoot】SpringBoot 事件监听机制（十六）

　　本例介绍SpringBoot的事件监听机制及使用

　　主要有ApplicationContextInitializer（上下文初始化器）、SpringApplicationRunListener（Spring应用运行监听器）、ApplicationRunner（启动加载类）、CommandLineRunner（启动加载类）

　　关于调用流程参考【SpringBoot】SpringBoot 启动原理（十五）

ApplicationContextInitializer（上下文初始化器）

　　1、新建一个SpringBoot Web项目

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6 
 7     <groupId>com.test</groupId>
 8     <artifactId>test-springboot-runner</artifactId>
 9     <version>1.0-SNAPSHOT</version>
10 
11     <parent>
12         <groupId>org.springframework.boot</groupId>
13         <artifactId>spring-boot-starter-parent</artifactId>
14         <version>2.1.8.RELEASE</version>
15     </parent>
16 
17     <properties>
18 
19         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
20         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
21         <java.version>1.8</java.version>
22     </properties>
23 
24     <dependencies>
25 
26         <dependency>
27             <groupId>org.springframework.boot</groupId>
28             <artifactId>spring-boot-starter-web</artifactId>
29         </dependency>
30 
31 
32         <dependency>
33             <groupId>org.springframework.boot</groupId>
34             <artifactId>spring-boot-starter-test</artifactId>
35             <scope>test</scope>
36         </dependency>
37 
38     </dependencies>
39 
40 
41     <!-- SpringBoot打包插件，可以将代码打包成一个可执行的jar包 -->
42     <build>
43         <plugins>
44             <plugin>
45                 <groupId>org.springframework.boot</groupId>
46                 <artifactId>spring-boot-maven-plugin</artifactId>
47             </plugin>
48         </plugins>
49     </build>
50 
51 </project>
View Code

　　2、新建HelloApplicationContextInitializer类，实现ApplicationContextInitializer接口，如下：

 1 package com.test.springboot.listener;
 2 
 3 import org.springframework.context.ApplicationContextInitializer;
 4 import org.springframework.context.ConfigurableApplicationContext;
 5 
 6 public class HelloApplicationContextInitializer implements ApplicationContextInitializer {
 7     @Override
 8     public void initialize(ConfigurableApplicationContext applicationContext) {
 9         System.out.println("====HelloApplicationContextInitializer======initialize：" + applicationContext);
10     }
11 }

　　3、将HelloApplicationContextInitializer加入SpringBoot中，在resources目录下新建文件META-INF/spring.factories，添加一下内容

1 # Initializers
2 org.springframework.context.ApplicationContextInitializer=\
3 com.test.springboot.listener.HelloApplicationContextInitializer

　　4、启动SpringBoot程序，查看控制台

　　　　

SpringApplicationRunListener（Spring应用运行监听器）

　　1、在SpringBoot Web项目中，新建HelloSpringApplicationRunListener类，实现SpringApplicationRunListener接口

 1 package com.test.springboot.listener;
 2 
 3 import org.springframework.boot.SpringApplication;
 4 import org.springframework.boot.SpringApplicationRunListener;
 5 import org.springframework.context.ConfigurableApplicationContext;
 6 import org.springframework.core.env.ConfigurableEnvironment;
 7 
 8 public class HelloSpringApplicationRunListener implements SpringApplicationRunListener {
 9 
10     public HelloSpringApplicationRunListener(SpringApplication application, String[] args) {
11 
12     }
13 
14     @Override
15     public void starting() {
16         System.out.println("===HelloSpringApplicationRunListener===starting");
17     }
18 
19     @Override
20     public void environmentPrepared(ConfigurableEnvironment environment) {
21         System.out.println("===os.name：" + environment.getSystemProperties().get("os.name") );
22         System.out.println("===HelloSpringApplicationRunListener===environmentPrepared");
23     }
24 
25     @Override
26     public void contextPrepared(ConfigurableApplicationContext context) {
27         System.out.println("===HelloSpringApplicationRunListener===contextPrepared");
28     }
29 
30     @Override
31     public void contextLoaded(ConfigurableApplicationContext context) {
32         System.out.println("===HelloSpringApplicationRunListener===contextLoaded");
33     }
34 
35     @Override
36     public void started(ConfigurableApplicationContext context) {
37         System.out.println("===HelloSpringApplicationRunListener===started");
38     }
39 
40     @Override
41     public void running(ConfigurableApplicationContext context) {
42         System.out.println("===HelloSpringApplicationRunListener===running");
43     }
44 
45     @Override
46     public void failed(ConfigurableApplicationContext context, Throwable exception) {
47         System.out.println("===HelloSpringApplicationRunListener===failed");
48     }
49 }

　　　　注意：HelloSpringApplicationRunListener必须添加构造方法，否则会包如下错误

　　　　

　　　　HelloSpringApplicationRunListener的构造方法编写，可以参考SpringApplicationRunListener的其他实现类，如：EventPublishingRunListener

 1 public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
 2 
 3     private final SpringApplication application;
 4 
 5     private final String[] args;
 6 
 7     private final SimpleApplicationEventMulticaster initialMulticaster;
 8 
 9     public EventPublishingRunListener(SpringApplication application, String[] args) {
10         this.application = application;
11         this.args = args;
12         this.initialMulticaster = new SimpleApplicationEventMulticaster();
13         for (ApplicationListener<?> listener : application.getListeners()) {
14             this.initialMulticaster.addApplicationListener(listener);
15         }
16     }
17 
18     ...
19 
20 }

　　2、将HelloSpringApplicationRunListener加入SpringBoot中，在resources目录下新建文件META-INF/spring.factories，添加一下内容

1 # Run Listeners
2 org.springframework.boot.SpringApplicationRunListener=\
3 com.test.springboot.listener.HelloSpringApplicationRunListener

　　3、测试启动SpringBoot程序，查看控制台

　　　　

ApplicationRunner（启动加载类）

　　1、在SpringBoot Web项目中，新建HelloApplicationRunner类，实现接口 ApplicationRunner

1 @Component
2 public class HelloApplicationRunner implements ApplicationRunner {
3     @Override
4     public void run(ApplicationArguments args) throws Exception {
5         System.out.println("===HelloApplicationRunner===run");
6     }
7 }

　　2、需要在HelloApplicationRunner类上加上注解@Component

　　3、启动SpringBoot项目，查看是否在启动时，调用了run方法

　　　　

CommandLineRunner（启动加载类）

　　1、在SpringBoot Web项目中，新建HelloCommandLineRunner类，实现接口 CommandLineRunner

1 @Component
2 public class HelloCommandLineRunner implements CommandLineRunner {
3     @Override
4     public void run(String... args) throws Exception {
5         System.out.println("===HelloCommandLineRunner===run：" + Arrays.asList(args));
6     }
7 }

 

　　2、需要在HelloCommandLineRunner类上加上注解@Component

　　3、启动SpringBoot项目，查看是否在启动时，调用了run方法

　　　　

　　4、同时注入ApplicationRunner和CommandLineRunner，ApplicationRunner先回调，CommandLineRunner再回调

 

 

 

 

 

　　

posted on 2020-03-08 11:42  H__D  阅读(534)  评论(0)  编辑  收藏  举报
 
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