Spring Boot + Apache Commons Export Data to CSV Example

Hello everyone, today we will learn how to export and download the data as a CSV file in a Spring Boot project. CSV stands for Comma-Separated-Values and it's a common format for doing a bulk data transfer between systems. For creating and parsing CSV files, we will use Apache Commons' 3rd-party library. 


Technologies used 

  • Spring Boot
  • Apache Commons
  • Spring Data JPA
  • H2DB
  • Maven

Project directory



Maven[pom.xml] 

A Project Object Model or POM is the fundamental unit of work in Maven. It is an XML file that contains information about the project and configuration details utilized by Maven to build the project.
<?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>2.1.1.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springboot_export_csv_apache_commons</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_export_csv_apache_commons</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-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-csv</artifactId>
            <version>1.8</version>
        </dependency>
    </dependencies>

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

</project>


Create Employee Model

package com.example.demo.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "employee")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;
    private String email;
    private String country;
    private int age;
    private String role;

    public Employee() {
        super();
    }

    public Employee(String name, String email, String country, 
                     int age, String role) {
        super();

        this.name = name;
        this.email = email;
        this.country = country;
        this.age = age;
        this.role = role;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

}


Create EmployeeRepository

package com.example.demo.repository;
import org.springframework.data.repository.CrudRepository;
import com.example.demo.model.Employee;

public interface EmployeeRepository 
           extends CrudRepository<Employee, Long> {

}


Create Employee Service

package com.example.demo.service;

import java.io.ByteArrayInputStream;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.example.demo.helper.CSVHelper;
import com.example.demo.model.Employee;
import com.example.demo.repository.EmployeeRepository;

@Service
public class EmployeeService {
    @Autowired
    EmployeeRepository employeeRepository;

    public List<Employee> fetchAll() {
        return (List<Employee>) employeeRepository.findAll();

    }

    public ByteArrayInputStream load() {
        List<Employee> tutorials = fetchAll();

        ByteArrayInputStream in = CSVHelper.employeesToCSV(tutorials);
        return in;
    }
}


Create CSVHelper

package com.example.demo.helper;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.List;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import org.apache.tomcat.util.http.fileupload.ByteArrayOutputStream;
import com.example.demo.model.Employee;

public class CSVHelper {

    public static ByteArrayInputStream 
            employeesToCSV(List<Employee> employees)
           {
        final CSVFormat format = CSVFormat.DEFAULT.withHeader
                ("ID", "Name", "Email", "Age", "Country", "Role");

        try (

                ByteArrayOutputStream out = 
                                  new ByteArrayOutputStream();
                CSVPrinter csvPrinter = 
                     new CSVPrinter(new PrintWriter(out), 
                                        format);) {
            for (Employee emp : employees) {
                List<String> data = Arrays.asList(String
                       .valueOf(emp.getId()), 
                          emp.getName(), emp.getEmail(),
                            String.valueOf(emp.getAge()), 
                               emp.getCountry(),
                                  emp.getRole());

                csvPrinter.printRecord(data);
            }

            csvPrinter.flush();
            return new ByteArrayInputStream(out.toByteArray());

        } catch (IOException e) {
            throw new RuntimeException
               ("fail to import data to CSV file: " 
                              + e.getMessage());
        }
    }
}


Create EmployeeController

package com.example.demo.controller;

import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import com.example.demo.service.EmployeeService;

@Controller
public class EmployeeController {

    @Autowired
    EmployeeService employeeService;

    @GetMapping("/export-employees")
    public ResponseEntity<InputStreamResource> 
             exportCSV(HttpServletResponse response) 
                          throws Exception {

        String filename = "employees.csv";
        InputStreamResource file = new InputStreamResource
                       (employeeService.load());

        return ResponseEntity.ok()
                 .header(HttpHeaders.CONTENT_DISPOSITION, 
                    "attachment; filename=" + filename)
                       .contentType(MediaType
                           .parseMediaType("application/csv")).
          body(file);

    }
}


Spring Boot Main Driver

package com.example.demo;

import java.util.ArrayList;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.example.demo.model.Employee;
import com.example.demo.repository.EmployeeRepository;

@SpringBootApplication
public class SpringbootExportCsvDemoApplication 
                   implements CommandLineRunner {

    @Autowired
    EmployeeRepository employeeRepository;

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

    @Override
    public void run(String... args) throws Exception {
        List<Employee> employees = new ArrayList<>();

        // create dummy employees
        employees.add(new Employee("Dummy-1", "dummy1@example.com", 
                 "India", 35, "Lead Tester"));
        employees.add(new Employee("Dummy-2", "dummy2@srovoki.me", 
                "USA", 25, "Tester"));
        employees.add(new Employee("Dummy-3", "dummy3@gmail.com", 
                "Japan", 29, "Sr.Tester"));
        employees.add(new Employee("Dummy-1", "dummy1@example.com", 
                "India", 35, "Lead Tester"));
        employees.add(new Employee("Dummy-2", "dummy2@srovoki.me", 
                "USA", 25, "Tester"));
        employees.add(new Employee("Dummy-3", "dummy3@gmail.com", 
                "Japan", 29, "Sr.Tester"));
        employees.add(new Employee("Dummy-1", "dummy1@example.com", 
                "India", 35, "Lead Tester"));
        employees.add(new Employee("Dummy-2", "dummy2@srovoki.me", 
                "USA", 25, "Tester"));
        employees.add(new Employee("Dummy-3", "dummy3@gmail.com", 
                "Japan", 29, "Sr.Tester"));
        employees.add(new Employee("Dummy-1", "dummy1@example.com", 
                "India", 35, "Lead Tester"));
        employees.add(new Employee("Dummy-2", "dummy2@srovoki.me", 
                "USA", 25, "Tester"));
        employees.add(new Employee("Dummy-3", "dummy3@gmail.com", 
                "Japan", 29, "Sr.Tester"));
        employees.add(new Employee("Dummy-1", "dummy1@example.com", 
                "India", 35, "Lead Tester"));
        employees.add(new Employee("Dummy-2", "dummy2@srovoki.me", 
                "USA", 25, "Tester"));
        employees.add(new Employee("Dummy-3", "dummy3@gmail.com", 
                "Japan", 29, "Sr.Tester"));
        employeeRepository.saveAll(employees);
    }
}

Download the complete source code - click here                                        

Local Setup and Run the application

Step1: Download or clone the source code from GitHub to a local machine - Click here


Step 2: mvn clean install


Step 3: Run the Spring Boot application - mvn spring-boot:run

Hit this URL in your local system, http://localhost:8080/export-employees

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