JAVA 자료구조 Spring Batch to Read From MongoDB and Generate XML Files

2020.09.21 22:03

Spring Batch to Read From MongoDB and Generate XML Files

We take a look at how to use these two popular and open source database projects together to generate XML file versions of our data.

This article is all about how to use Spring Batch jobs to read data from a Mongo Collection and generate an XML file. This will be very useful for generating reports out of mongoDB using Spring Batch. I was really struggling to get a running Maven project of Spring Batch with MongoDB read operations to generate XML when I was researching it via various internet sources. This running project might be helpful.

Technology stack:

Java 8
Maven 3.5.2
Spring Boot 1.5.2
MongoDB 3.6

The complete, running Maven project can be downloaded from my GitHub repo.

1. pom.xml File

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-oxm</artifactId>
        <version>4.3.7.RELEASE</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-mongodb</artifactId>
        <version>1.9.8.RELEASE</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-batch</artifactId>
        <version>1.5.2.RELEASE</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <version>1.5.2.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

2) application.properties

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

3) Spring Batch Jobs

Create a job that will read from Mongodb and write into an XML file.

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어린이용이며, 설치가 필요없는 브라우저 게임입니다.
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package com.batch.mongo.mongotoxml.jobs;
 
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;
 
import com.batch.mongo.mongotoxml.model.Employee;
 
@Configuration
@EnableBatchProcessing
public class MongoDBReader {
 
  @Autowired
  private JobBuilderFactory jobBuilderFactory;
  @Autowired
  private StepBuilderFactory stepBuilderFactory;
 
  @Autowired
  private MongoTemplate mongoTemplate;
 
  @Bean
  public Job readEmployee() throws Exception {
    return jobBuilderFactory.get("readEmployee").flow(step1()).end().build();
  }
 
  @Bean
  public Step step1() throws Exception {
    return stepBuilderFactory.get("step1").<Employee, Employee>chunk(10).reader(reader())
        .writer(writer()).build();
  }
 
 
@Bean
  public MongoItemReader<Employee> reader() {
    MongoItemReader<Employee> reader = new MongoItemReader<>();
    reader.setTemplate(mongoTemplate);
    reader.setSort(new HashMap<String, Sort.Direction>() {{
      put("_id", Direction.DESC);
    }});
    reader.setTargetType(Employee.class);
    reader.setQuery("{}");
    return reader;
  }
 
  @Bean
  public StaxEventItemWriter<Employee> writer() {
    StaxEventItemWriter<Employee> writer = new StaxEventItemWriter<>();
    writer.setResource(new FileSystemResource("xml/employees.xml"));
    writer.setMarshaller(userUnmarshaller());
    writer.setRootTagName("employees");
    return writer;
  }
 
 
@Bean
  public XStreamMarshaller userUnmarshaller() {
    XStreamMarshaller unMarshaller = new XStreamMarshaller();
    Map<String, Class> aliases = new HashMap<String, Class>();
    aliases.put("employee", Employee.class);
    unMarshaller.setAliases(aliases);
    return unMarshaller;
  }
}

4) Fetching a Record From the MongoDB Employee Collection to an Object and Writing it to an XML File.

import java.math.BigDecimal;
import lombok.Data;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.annotation.Id;
 
@Data
@Document(collection = "employee")
public class Employee {
	@Id
	private int id;
	private String firstName;
	private String lastName;
	private String department;
	private BigDecimal salary;
}

5) MongoDB Data Insert

{
    "_id" : 1,
    "firstName" : "Peter",
    "lastName" : "Stephen",
    "depertment" : "Technology",
    "salary" : 320.4
}

6) Run the Application

package com.batch.mongo;
 
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);
  }
}

7) Output

<?xml version="1.0" encoding="UTF-8"?>
<employees>
    <employee>
        <id>3</id>
        <firstName>Joe</firstName>
        <lastName>Spen</lastName>
        <salary>5320.4</salary>
    </employee>
    <employee>
        <id>2</id>
        <firstName>John</firstName>
        <lastName>Sender</lastName>
        <salary>2320.4</salary>
    </employee>
    <employee>
        <id>1</id>
        <firstName>Peter</firstName>
        <lastName>Stephen</lastName>
        <salary>320.4</salary>
    </employee>
</employees>

Hope this will help you to understand Spring Batch with MongoDB read operations. Happy learning!

[출처] https://dzone.com/articles/spring-batch-to-read-from-mongodb-and-generate-xml

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