这里对Spring Batch 进行批处理实践。
介绍本文将会讲述SpringBatch 如何搭建并运行起来的。本教程，将会介绍从磁盘读取文件，并写入MySql 中。
什么是Spring BatchSpring Batch 是Spring的子项目，基于Spring的批处理的框架，通过其可以构建出批量的批处理框架。
官方地址：github.com/spring-projects/spring-batch
入门案例新建Spring Boot 项目
选择Spring Batch 
继续等待 
pom 依赖如下
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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-parent</artifactId>
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<version>2.3.1.RELEASE</version>
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<relativePath/> <!-- lookup parent from repository -->
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</parent>
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<groupId>com.example</groupId>
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<artifactId>demo</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<name>demo</name>
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<description>Demo project for Spring Boot</description>
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<properties>
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<java.version>1.8</java.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-batch</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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<exclusions>
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<exclusion>
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<groupId>org.junit.vintage</groupId>
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<artifactId>junit-vintage-engine</artifactId>
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</exclusion>
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</exclusions>
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</dependency>
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<dependency>
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<groupId>org.springframework.batch</groupId>
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<artifactId>spring-batch-test</artifactId>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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</plugin>
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</plugins>
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</build>
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</project>
一个job有读写处理这三个部分组成。通过JobLauncher启动Job 步骤为 读、处理、写 三个步骤
一个例子初始化目录结构如下 
读取
从数组中读取三个字符
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package com.example.demo.step;
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import org.springframework.batch.item.ItemReader;
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import org.springframework.batch.item.NonTransientResourceException;
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import org.springframework.batch.item.ParseException;
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import org.springframework.batch.item.UnexpectedInputException;
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public class Reader implements ItemReader<String> {
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private String[] message = {"ming", "mingming", "mingmingming"};
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private int count = 0;
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@Override
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public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
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if(count < message.length){
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return message[count++];
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}else{
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count = 0;
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}
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}
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}
每次将会调用reader 方法，进行读取一个，
处理
字符串转为大写
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package com.example.demo.step;
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import org.springframework.batch.item.ItemProcessor;
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public class Processor implements ItemProcessor<String, String> {
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@Override
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public String process(String s) throws Exception {
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return s.toUpperCase();
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}
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}
字符串将会调用其方法将其处理为大写
写
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package com.example.demo.step;
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import org.springframework.batch.item.ItemWriter;
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import java.util.List;
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public class Writer implements ItemWriter<String> {
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@Override
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public void write(List<? extends String> list) throws Exception {
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for (String s : list) {
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System.out.println("Writing the data " + s);
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}
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}
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}
监听
任务成功完成后往控制台输出一行字符串
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package com.example.demo.step;
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import org.springframework.batch.core.BatchStatus;
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import org.springframework.batch.core.JobExecution;
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import org.springframework.batch.core.listener.JobExecutionListenerSupport;
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public class JobCompletionListener extends JobExecutionListenerSupport {
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@Override
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public void afterJob(JobExecution jobExecution) {
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// 项目完成以后调用
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if(jobExecution.getStatus() == BatchStatus.COMPLETED){
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System.out.println("项目已经完成");
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}
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}
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}
Config
对项目进行配置
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package com.example.demo.config;
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import com.example.demo.step.JobCompletionListener;
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import com.example.demo.step.Processor;
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import com.example.demo.step.Reader;
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import com.example.demo.step.Writer;
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import org.springframework.batch.core.Job;
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import org.springframework.batch.core.JobExecutionListener;
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import org.springframework.batch.core.Step;
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import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
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import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
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import org.springframework.batch.core.launch.support.RunIdIncrementer;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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@Configuration
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public class BatchConfig {
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@Autowired
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public JobBuilderFactory jobBuilderFactory;
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@Autowired
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public StepBuilderFactory stepBuilderFactory;
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@Bean
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public Job processJob() {
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return jobBuilderFactory.get("processJob")
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.incrementer(new RunIdIncrementer()).listener(listener())// 监听
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.flow(orderStep1()).end().build(); // 创建步骤1
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}
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@Bean
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// 步骤1 bean 先读再写
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public Step orderStep1() {
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return stepBuilderFactory.get("orderStep1").<String, String> chunk(1)
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.reader(new Reader()).processor(new Processor()) // 读取。处理
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.writer(new Writer()).build(); // 最后写
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}
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@Bean
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public JobExecutionListener listener() {
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return new JobCompletionListener(); // 创建监听
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}
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}
用来启动应用
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package com.example.demo.controller;
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import org.springframework.batch.core.Job;
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import org.springframework.batch.core.JobParameters;
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import org.springframework.batch.core.JobParametersBuilder;
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import org.springframework.batch.core.launch.JobLauncher;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.web.bind.annotation.RequestMapping;
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import org.springframework.web.bind.annotation.RestController;
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@RestController
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public class JobInvokerController {
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@Autowired
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JobLauncher jobLauncher;
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@Autowired
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Job processJob;
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@RequestMapping("/invokejob")
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public String handle() throws Exception {
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JobParameters jobParameters = new JobParametersBuilder().addLong("time", System.currentTimeMillis())
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.toJobParameters();
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jobLauncher.run(processJob, jobParameters);
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return "Batch job has been invoked";
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}
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}
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spring:
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batch:
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job:
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enabled: false
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datasource:
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url: jdbc:h2:file:./DB
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jpa:
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properties:
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hibernate:
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hbm2ddl:
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auto: update
Spring Batch在加载的时候job默认都会执行，把spring.batch.job.enabled置为false，即把job设置成不可用，应用便会根据jobLauncher.run来执行。下面2行是数据库的配置，不配置也可以，使用的嵌入式数据库h2
添加注解Spring Boot入口类：加注解@EnableBatchProcessing
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package com.example.demo;
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import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
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import org.springframework.boot.SpringApplication;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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@SpringBootApplication
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@EnableBatchProcessing
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public class DemoApplication {
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public static void main(String[] args) {
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SpringApplication.run(DemoApplication.class, args);
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}
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}
此时项目run 访问 http://localhost:8080/invokejob 项目已经启动
