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 Batch

Spring 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

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <parent>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-parent</artifactId>        <version>2.3.1.RELEASE</version>        <relativePath/> <!-- lookup parent from repository -->    </parent>    <groupId>com.example</groupId>    <artifactId>demo</artifactId>    <version>0.0.1-SNAPSHOT</version>    <name>demo</name>    <description>Demo project for Spring Boot</description>    <properties>        <java.version>1.8</java.version>    </properties>    <dependencies>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-batch</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-test</artifactId>            <scope>test</scope>            <exclusions>                <exclusion>                    <groupId>org.junit.vintage</groupId>                    <artifactId>junit-vintage-engine</artifactId>                </exclusion>            </exclusions>        </dependency>        <dependency>            <groupId>org.springframework.batch</groupId>            <artifactId>spring-batch-test</artifactId>            <scope>test</scope>        </dependency>    </dependencies>    <build>        <plugins>            <plugin>                <groupId>org.springframework.boot</groupId>                <artifactId>spring-boot-maven-plugin</artifactId>            </plugin>        </plugins>    </build></project>

什么是 Spring Batch works

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

package com.example.demo.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[] message = {"ming", "mingming", "mingmingming"};        private int count = 0;        @Override    public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {        if(count < message.length){            return message[count++];        }else{            count = 0;        }    }}

每次将会调用reader 方法，进行读取一个，

处理

字符串转为大写

package com.example.demo.step;import org.springframework.batch.item.ItemProcessor;public class Processor implements ItemProcessor<String, String> {    @Override    public String process(String s) throws Exception {        return s.toUpperCase();    }}

字符串将会调用其方法将其处理为大写

写

package com.example.demo.step;import org.springframework.batch.item.ItemWriter;import java.util.List;public class Writer implements ItemWriter<String> {    @Override    public void write(List<? extends String> list) throws Exception {        for (String s : list) {            System.out.println("Writing the data " + s);        }    }}

监听

任务成功完成后往控制台输出一行字符串

package com.example.demo.step;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) {        // 项目完成以后调用        if(jobExecution.getStatus() == BatchStatus.COMPLETED){            System.out.println("项目已经完成");        }    }}

Config

对项目进行配置

package com.example.demo.config;import com.example.demo.step.JobCompletionListener;import com.example.demo.step.Processor;import com.example.demo.step.Reader;import com.example.demo.step.Writer;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;@Configurationpublic class BatchConfig {    @Autowired    public JobBuilderFactory jobBuilderFactory;    @Autowired    public StepBuilderFactory stepBuilderFactory;    @Bean    public Job processJob() {        return jobBuilderFactory.get("processJob")                .incrementer(new RunIdIncrementer()).listener(listener())// 监听                .flow(orderStep1()).end().build(); // 创建步骤1     }    @Bean    // 步骤1 bean 先读再写    public Step orderStep1() {        return stepBuilderFactory.get("orderStep1").<String, String> chunk(1)                .reader(new Reader()).processor(new Processor())    // 读取。处理                .writer(new Writer()).build();  // 最后写    }    @Bean    public JobExecutionListener listener() {        return new JobCompletionListener(); // 创建监听    }}

配置Controller

用来启动应用

package com.example.demo.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;@RestControllerpublic 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";    }}

配置文件

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

package com.example.demo;import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication@EnableBatchProcessingpublic class DemoApplication {    public static void main(String[] args) {        SpringApplication.run(DemoApplication.class, args);    }}

Run

此时项目run
访问 http://localhost:8080/invokejob 项目已经启动

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