Spring Batch Example in Spring boot - Mongo Database to XML

In this post, we will show you how to configure a Spring Batch job to read data from mongo database and write into XML file.

Project structure

This is a directory structure of the standard gradle project.

Project dependencies

task wrapper(type: Wrapper) {
    gradleVersion = '3.2.1'
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

sourceCompatibility = 1.8

repositories {
    mavenLocal()
    mavenCentral()
}


dependencies {
    compile 'org.springframework:spring-oxm:4.3.7.RELEASE'
    compile 'org.springframework.data:spring-data-mongodb:1.9.8.RELEASE'
    compileOnly('org.projectlombok:lombok:1.16.12')
    compile('org.springframework.boot:spring-boot-starter-batch:1.5.2.RELEASE')
    testCompile('org.springframework.boot:spring-boot-starter-test:1.5.2.RELEASE')
}
buildscript {
    repositories {
        mavenLocal()
        jcenter()
    }
    dependencies {
        classpath "org.springframework.boot:spring-boot-gradle-plugin:1.5.2.RELEASE"
    }
}

application.properties file

spring.data.mongodb.host=127.0.0.1
spring.data.mongodb.port=27017
spring.data.mongodb.database=springbatch

Spring Batch Jobs

Create a job which will read from mongodb and write into XML file.

package com.walking.techie.mongotoxml.jobs;

import com.walking.techie.mongotoxml.model.Report;
import java.util.HashMap;
import java.util.Map;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.item.data.MongoItemReader;
import org.springframework.batch.item.xml.StaxEventItemWriter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.FileSystemResource;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.oxm.xstream.XStreamMarshaller;

@Configuration
@EnableBatchProcessing
public class ReadFromDB {

  @Autowired
  private JobBuilderFactory jobBuilderFactory;
  @Autowired
  private StepBuilderFactory stepBuilderFactory;

  @Autowired
  private MongoTemplate mongoTemplate;

  @Bean
  public Job readReport() throws Exception {
    return jobBuilderFactory.get("readReport").flow(step1()).end().build();
  }

  @Bean
  public Step step1() throws Exception {
    return stepBuilderFactory.get("step1").<Report, Report>chunk(10).reader(reader())
        .writer(writer()).build();
  }


  @Bean
  public MongoItemReader<Report> reader() {
    MongoItemReader<Report> reader = new MongoItemReader<>();
    reader.setTemplate(mongoTemplate);
    reader.setSort(new HashMap<String, Sort.Direction>() {{
      put("_id", Direction.DESC);
    }});
    reader.setTargetType(Report.class);
    reader.setQuery("{}");
    return reader;
  }

  @Bean
  public StaxEventItemWriter<Report> writer() {
    StaxEventItemWriter<Report> writer = new StaxEventItemWriter<>();
    writer.setResource(new FileSystemResource("xml/mongo.xml"));
    writer.setMarshaller(userUnmarshaller());
    writer.setRootTagName("report");
    return writer;
  }

  @Bean
  public XStreamMarshaller userUnmarshaller() {
    XStreamMarshaller unMarshaller = new XStreamMarshaller();
    Map<String, Class> aliases = new HashMap<String, Class>();
    aliases.put("report", Report.class);
    unMarshaller.setAliases(aliases);
    return unMarshaller;
  }
}

Map record from mongodb report collection to Report object and write to XML file.

A Java model class

package com.walking.techie.mongotoxml.model;


import java.math.BigDecimal;
import java.util.Date;
import lombok.Data;
import org.springframework.data.mongodb.core.mapping.Document;

@Data
@Document(collection = "report")
public class Report {

  private int id;
  private Date date;
  private long impression;
  private int clicks;
  private BigDecimal earning;
}

Run Application

package com.walking.techie;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
public class Application {

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

Output

Output of the application will store in xml/mongo.xml. Below is formatted output.

<?xml version="1.0" encoding="UTF-8"?>
<report>
  <report>
    <id>3</id>
    <date>2017-03-29 18:30:00.0 UTC</date>
    <impression>431436</impression>
    <clicks>86</clicks>
    <earning>270.80</earning>
  </report>
  <report>
    <id>2</id>
    <date>2017-03-28 18:30:00.0 UTC</date>
    <impression>339100</impression>
    <clicks>60</clicks>
    <earning>320.88</earning>
  </report>
  <report>
    <id>1</id>
    <date>2017-03-27 18:30:00.0 UTC</date>
    <impression>139237</impression>
    <clicks>50</clicks>
    <earning>220.90</earning>
  </report>
</report>

output on console

2017-03-29 13:02:57.916  INFO 37073 --- [           main] o.s.b.c.l.support.SimpleJobLauncher      : Job: [FlowJob: [name=readReport]] launched with the following parameters: [{}]
2017-03-29 13:02:57.935  INFO 37073 --- [           main] o.s.batch.core.job.SimpleStepHandler     : Executing step: [step1]
2017-03-29 13:02:58.003  INFO 37073 --- [           main] org.mongodb.driver.connection            : Opened connection [connectionId{localValue:2, serverValue:394}] to 127.0.0.1:27017
2017-03-29 13:02:58.075  INFO 37073 --- [           main] o.s.b.c.l.support.SimpleJobLauncher      : Job: [FlowJob: [name=readReport]] completed with the following parameters: [{}] and the following status: [COMPLETED]

Note : This code has been compiled and run on mac notebook and intellij IDEA.