ApplicationRunner & CommandLineRunner & @PostConstruct & static前言一、四种实现方式二、执行结果三、注意异常总结

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我是靠谱客的博主正直学姐，这篇文章主要介绍ApplicationRunner & CommandLineRunner & @PostConstruct & static前言一、四种实现方式二、执行结果三、注意异常总结，现在分享给大家，希望可以做个参考。

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系统启动后加载初始化数据

前言
一、四种实现方式
- ApplicationRunner
- CommandLineRunner
- @PostConstruct
- static
二、执行结果
三、注意异常
总结

前言

不是很建议使用这些类
建议：
1：页面按钮（后端读表放入缓存，还可以实现reload/unload等）初始化数据
2：懒加载机制，后端用到时，再去读表+放入缓存
3：如果是某些配置，如：请求url，配置参数，那么一定要写到配置文件里，不要这样启动后再去加载

一、四种实现方式

被调用服务 InitService

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import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
@Slf4j
@Service
public class InitService {
public void init() {
log.info("InitService");
}
}

ApplicationRunner

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import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;
import java.util.concurrent.Executors;
@Slf4j
@Component
public class ApplicationRunnerExtend implements ApplicationRunner {
private final InitService initService;
public ApplicationRunnerExtend(InitService initService) {
this.initService = initService;
}
@Override
public void run(ApplicationArguments args) throws Exception {
log.info("-----------ApplicationRunnerExtend-----------");
Executors.newSingleThreadExecutor().execute(() -> {
log.info("开启线程执行");
initService.init();
});
}
}

CommandLineRunner

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import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
@Slf4j
@Component
public class CommandLineRunnerExtend implements CommandLineRunner {
private final InitService initService;
public CommandLineRunnerExtend(InitService initService) {
this.initService = initService;
}
@Override
public void run(String... args) throws Exception {
log.info("-----------CommandLineRunnerExtend-----------");
initService.init();
}
}

@PostConstruct

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import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
@Slf4j
@Component
public class PostConstructExtend {
private final InitService initService;
public PostConstructExtend(InitService initService) {
this.initService = initService;
}
@PostConstruct
public void init() {
log.info("-----------PostConstructExtend-----------");
initService.init();
}
}

static

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import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
@Slf4j
@Component
public class StaticExtend {
static {
InitService initService = new InitService();
log.info("-----------StaticExtend-----------");
initService.init();
}
}

二、执行结果

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[
main] o.a.c.c.C.[Tomcat].[localhost].[/]
: Initializing Spring embedded WebApplicationContext
[
main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 891 ms
[
main] c.e.demo.runner.PostConstructExtend
: -----------PostConstructExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[
main] com.example.demo.runner.StaticExtend
: -----------StaticExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[
main] o.s.b.w.embedded.tomcat.TomcatWebServer
: Tomcat started on port(s): 8080 (http) with context path ''
[
main] com.example.demo.TaoDemoApplication
: Started TaoDemoApplication in 21.677 seconds (JVM running for 27.449)
[
main] c.e.demo.runner.ApplicationRunnerExtend
: -----------ApplicationRunnerExtend-----------
[
main] c.e.demo.runner.CommandLineRunnerExtend
: -----------CommandLineRunnerExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[pool-2-thread-1] c.e.demo.runner.ApplicationRunnerExtend
: 开启线程执行
[pool-2-thread-1] com.example.demo.runner.InitService
: InitService

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[
main] o.a.c.c.C.[Tomcat].[localhost].[/]
: Initializing Spring embedded WebApplicationContext
[
main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 891 ms
[
main] c.e.demo.runner.PostConstructExtend
: -----------PostConstructExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[
main] com.example.demo.runner.StaticExtend
: -----------StaticExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[
main] o.s.b.w.embedded.tomcat.TomcatWebServer
: Tomcat started on port(s): 8080 (http) with context path ''
[
main] com.example.demo.TaoDemoApplication
: Started TaoDemoApplication in 21.677 seconds (JVM running for 27.449)
[
main] c.e.demo.runner.ApplicationRunnerExtend
: -----------ApplicationRunnerExtend-----------
[
main] c.e.demo.runner.CommandLineRunnerExtend
: -----------CommandLineRunnerExtend-----------
[
main] com.example.demo.runner.InitService
: InitService
[pool-2-thread-1] c.e.demo.runner.ApplicationRunnerExtend
: 开启线程执行
[pool-2-thread-1] com.example.demo.runner.InitService
: InitService

三、注意异常

InitService中新增方法（会抛异常）

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public void initTwo(){
log.info("InitService");
String str = null;
str.contains("123");
}

ApplicationRunner 和 CommandLineRunner虽然是在spring启动成功后再执行的，但如果是执行initTwo，则会因为异常导致启动失败。

建议：
1：异步执行initTwo()，不造成spring启动失败

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public void run(ApplicationArguments args) throws Exception {
log.info("-----------ApplicationRunnerExtend-----------");
Executors.newSingleThreadExecutor().execute(() -> {
log.info("开启线程执行");
initService.initTwo();
});
}

2：使用try/catch捕获异常

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@Override
public void run(String... args) throws Exception {
log.info("-----------CommandLineRunnerExtend-----------");
try {
initService.initTwo();
}catch (Exception e){
log.error("异常了！！！");
}
}