spring boot -- 监听器

傷城~ 2022-06-17 13:41 208阅读 0赞

一些系统配置，存储在数据库中，需要在项目启动时加载进缓存。此时可以实现ApplicationListener类来实现监听。

第一步：

package com.lic.base.servlet;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.context.ApplicationListener;
    import org.springframework.context.event.ContextRefreshedEvent;
    
    import com.lic.app.system.service.impl.SysConfigService;
    import com.lic.base.tools.CacheHelp;
    
    public class StartApplicationListener implements ApplicationListener<ContextRefreshedEvent>{
    
    	protected Logger log = LoggerFactory.getLogger(StartApplicationListener.class);
    	@Override
    	public void onApplicationEvent(ContextRefreshedEvent event) {
    		
    		log.info("加载系统配置...");
    		
    		SysConfigService sysConfigService = event.getApplicationContext().getBean(SysConfigService.class);
    		
    		CacheHelp.SYS_CONFIG_MAP = sysConfigService.selectKeyValueByGroupCode(null);
    		
    		log.info("系统配置加载完成...");
    	}
    
    }

这个类 不会自动注册，需要我们手动注册。

第二步：

package com.lic.boot;
    
    import java.util.Properties;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ImportResource;
    
    import com.google.code.kaptcha.impl.DefaultKaptcha;
    import com.google.code.kaptcha.util.Config;
    import com.lic.base.servlet.StartApplicationListener;
    
    @SpringBootApplication
    @ImportResource("classpath:/spring/applicationContext.xml")
    //@Configuration
    @EnableAutoConfiguration
    //@ComponentScan("main.java.com.huike")
    // @EnableEurekaServer
    public class StartApplication {
    
    	private static final Logger log = LoggerFactory.getLogger(StartApplication.class);
    
    	public static void main(String[] args) {
    		log.info("服务开始启动了");
    		SpringApplication app = new SpringApplication(StartApplication.class);
    		app.addListeners(new StartApplicationListener());
    		app.run(args);
    	}
    }

运行可以看到控制台打印：

04-27 15:52:23.917 [main] INFO  com.huike.boot.StartApplication - 服务开始启动了
    04-27 15:52:24.489 [background-preinit] INFO  org.hibernate.validator.internal.util.Version - HV000001: Hibernate Validator 5.2.1.Final
    
      .   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Boot ::        (v1.4.3.RELEASE)
    
    04-27 15:52:24.870 [main] INFO  com.huike.boot.StartApplication - No active profile set, falling back to default profiles: default
    04-27 15:52:25.445 [main] WARN  org.mybatis.spring.mapper.ClassPathMapperScanner - No MyBatis mapper was found in '[com.huike.boot]' package. Please check your configuration.
    04-27 15:52:26.021 [main] INFO  org.apache.catalina.core.StandardService - Starting service Tomcat
    04-27 15:52:26.022 [main] INFO  org.apache.catalina.core.StandardEngine - Starting Servlet Engine: Apache Tomcat/8.5.6
    04-27 15:52:26.103 [localhost-startStop-1] INFO  org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/] - Initializing Spring embedded WebApplicationContext
    04-27 15:52:27.716 [main] INFO  com.huike.base.servlet.StartApplicationListener - 加载系统配置...
    04-27 15:52:28.013 [main] DEBUG com.huike.app.system.service.ISysConfigService.selectKeyValueByGroupCode - ==>  Preparing: select ckey, cvalue from sys_config where 1 = 1 
    04-27 15:52:28.030 [main] DEBUG com.huike.app.system.service.ISysConfigService.selectKeyValueByGroupCode - ==> Parameters: 
    04-27 15:52:28.045 [main] DEBUG com.huike.app.system.service.ISysConfigService.selectKeyValueByGroupCode - <==      Total: 21
    04-27 15:52:28.049 [main] INFO  com.huike.base.servlet.StartApplicationListener - 系统配置加载完成...
    04-27 15:52:28.054 [main] INFO  org.apache.coyote.http11.Http11NioProtocol - Initializing ProtocolHandler ["http-nio-8090"]
    04-27 15:52:28.062 [main] INFO  org.apache.coyote.http11.Http11NioProtocol - Starting ProtocolHandler [http-nio-8090]
    04-27 15:52:28.070 [main] INFO  org.apache.tomcat.util.net.NioSelectorPool - Using a shared selector for servlet write/read
    04-27 15:52:28.088 [main] INFO  com.huike.boot.StartApplication - Started StartApplication in 4.088 seconds (JVM running for 4.621)

打成jar包是可以使用的，但是打成war包就不能使用了。解决办法是在监听器上加一个@Component注解。

package com.huike.base.servlet;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.context.ApplicationListener;
    import org.springframework.context.annotation.Conditional;
    import org.springframework.context.event.ContextRefreshedEvent;
    import org.springframework.stereotype.Component;
    
    import com.huike.app.system.service.impl.SysConfigService;
    import com.huike.base.tools.CacheHelp;
    
    @Component
    public class StartApplicationListener implements ApplicationListener<ContextRefreshedEvent>{
    
    	protected Logger log = LoggerFactory.getLogger(StartApplicationListener.class);
    	@Override
    	public void onApplicationEvent(ContextRefreshedEvent event) {
    		
    		log.info("加载系统配置...");
    		
    		SysConfigService sysConfigService = event.getApplicationContext().getBean(SysConfigService.class);
    		
    		CacheHelp.SYS_CONFIG_MAP = sysConfigService.selectKeyValueByGroupCode(null);
    		
    		log.info("系统配置加载完成...");
    	}
    
    }

这样也会在项目启动时执行。