Spring Batch之批处理实践

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



    4.0.0
    
 org.springframework.boot
 spring-boot-starter-parent
 2.3.1.RELEASE
  
    
    com.example
    demo
    0.0.1-SNAPSHOT
    demo
    Demo project for Spring Boot

    
 1.8
    

    
 
     org.springframework.boot
     spring-boot-starter-batch
 
 
     org.springframework.boot
     spring-boot-starter-web
 

 
     org.springframework.boot
     spring-boot-starter-test
     test
     
  
      org.junit.vintage
      junit-vintage-engine
  
     
 
 
     org.springframework.batch
     spring-batch-test
     test
 
    

    
 
     
  org.springframework.boot
  spring-boot-maven-plugin


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 {
    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 {
    @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 {
    @Override
    public void write(List 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;


@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())// 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"). 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;


@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";
    }

}


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
@EnableBatchProcessing
public 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

Spring Batch之批处理实践

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