V2AS问路
Spring Boot下Spring Batch入门实例
阅读原文时间：2023年07月10日阅读：3

Spring Batch是什么能干什么，网上一搜就有，但是就是没有入门实例，能找到的例子也都是2.0的，看文档都是英文无从下手~~~，使用当前最新的版本整合网络上找到的例子。

关于基础不熟悉的，推荐读一下Spring Batch 批处理框架这本书，虽然讲的是2.0但基本概念没变。

1.1 How Spring Batch works?

一个Job有1个或多个Step组成，Step有读、处理、写三部分操作组成；通过JobLauncher启动Job，启动时从JobRepository获取Job Execution；当前运行的Job及Step的结果及状态保存在JobRepository中。

下面举个小例子，就是这篇文章中的例子，下面的这个例子版本是最新的：

  • spring-boot:2.0.1.RELEASE
  • spring-batch-4.0.1.RELEASE(Spring-Boot 2.0.1就是依赖的此版本)

下面这个例子实现的是：从变量中读取3个字符串全转化大写并输出到控制台，加了一个监听，当任务完成时输出一个字符串到控制台，通过web端来调用。

下面是项目的目录结构：

2.1 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.javainuse</groupId>
    <artifactId>springboot-batch</artifactId>
    <version>0.0.1</version>
    <packaging>jar</packaging>

    <name>SpringBatch</name>
    <description>Spring Batch-Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-batch</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.2 Item Reader

读取：从数组中读取3个字符串

package com.javainuse.step;

import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.NonTransientResourceException;
import org.springframework.batch.item.ParseException;
import org.springframework.batch.item.UnexpectedInputException;

public class Reader implements ItemReader<String> {

    private String[] messages = { "javainuse.com",
            "Welcome to Spring Batch Example",
            "We use H2 Database for this example" };

    private int count = 0;

    @Override
    public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {

        if (count < messages.length) {
            return messages[count++];
        } else {
            count = 0;
        }
        return null;
    }

}

2.3 Item Processor

处理：将字符串转为大写

package com.javainuse.step;

import org.springframework.batch.item.ItemProcessor;

public class Processor implements ItemProcessor<String, String> {

    @Override
    public String process(String data) throws Exception {
        return data.toUpperCase();
    }

}

2.4 Item Writer

输出：把转为大写的字符串输出到控制台

package com.javainuse.step;

import java.util.List;

import org.springframework.batch.item.ItemWriter;

public class Writer implements ItemWriter<String> {

    @Override
    public void write(List<? extends String> messages) throws Exception {
        for (String msg : messages) {
            System.out.println("Writing the data " + msg);
        }
    }

}

2.5 Listener

监听：任务成功完成后往控制台输出一行字符串

package com.javainuse.listener;

import org.springframework.batch.core.BatchStatus;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.listener.JobExecutionListenerSupport;

public class JobCompletionListener extends JobExecutionListenerSupport {

    @Override
    public void afterJob(JobExecution jobExecution) {
        if (jobExecution.getStatus() == BatchStatus.COMPLETED) {
            System.out.println("BATCH JOB COMPLETED SUCCESSFULLY");
        }
    }

}

2.6 Config

Spring Boot配置：

package com.javainuse.config;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobExecutionListener;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.launch.support.RunIdIncrementer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.javainuse.listener.JobCompletionListener;
import com.javainuse.step.Processor;
import com.javainuse.step.Reader;
import com.javainuse.step.Writer;

@Configuration
public class BatchConfig {

    @Autowired
    public JobBuilderFactory jobBuilderFactory;

    @Autowired
    public StepBuilderFactory stepBuilderFactory;

    @Bean
    public Job processJob() {
        return jobBuilderFactory.get("processJob")
                .incrementer(new RunIdIncrementer()).listener(listener())
                .flow(orderStep1()).end().build();
    }

    @Bean
    public Step orderStep1() {
        return stepBuilderFactory.get("orderStep1").<String, String> chunk(1)
                .reader(new Reader()).processor(new Processor())
                .writer(new Writer()).build();
    }

    @Bean
    public JobExecutionListener listener() {
        return new JobCompletionListener();
    }

}

2.7 Controller

控制器：配置web路由，访问/invokejob来调用任务

package com.javainuse.controller;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.JobParametersBuilder;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class JobInvokerController {

    @Autowired
    JobLauncher jobLauncher;

    @Autowired
    Job processJob;

    @RequestMapping("/invokejob")
    public String handle() throws Exception {

            JobParameters jobParameters = new JobParametersBuilder().addLong("time", System.currentTimeMillis())
                    .toJobParameters();
            jobLauncher.run(processJob, jobParameters);

        return "Batch job has been invoked";
    }
}

2.8 application.properties

配置：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

spring.batch.job.enabled=false
spring.datasource.url=jdbc:h2:file:./DB
spring.jpa.properties.hibernate.hbm2ddl.auto=update

2.9 Application

Spring Boot入口类：加注解@EnableBatchProcessing

package com.javainuse;

import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@EnableBatchProcessing
public class SpringBatchApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBatchApplication.class, args);
    }
}

启动这个Spring Boot项目，访问下面这个路径，会有如下输出

http://localhost:8080/invokejob

然后控制台会有如下输出：

我们可以使用H2-console来查看H2数据库，访问如下地址 http://localhost:8080/h2-console ， 选择如下数据库，输入JDBC URL：jdbc:h2:file:./DB，这是上文配置的，不用输入密码，直接点击Connect就可以了。

连上后显示如下：

左侧那些表就是Spring Batch自动创建的，至于每个表都是什么意思，可参考下面的那本书，这些建表的脚本存在于哪呢？可在spring-batch-core-xxx.jar包下的org.springframework.batch.core包下找到

查看batch-h2.properties可以看到相关的默认配置:

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