Spring Boot Tutorial-Spring Data JPA Simple Example

In this post we create a Employee management system which adds and retrieves employee details. 

Lets Begin

We make use of the h2 database. Maven will be as follows-

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>

 <groupId>com.EXP</groupId>
 <artifactId>SpringBootHelloWorld</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>

 <name>SpringBootHelloWorld</name>
 <description>Demo project for Spring Boot</description>

 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.4.1.RELEASE</version>
  <relativePath /> <!-- lookup parent from repository -->
 </parent>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  <java.version>1.8</java.version>
 </properties>

 <dependencies>
 
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
  </dependency>

  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-data-jpa</artifactId>
  </dependency>

  <dependency>
   <groupId>com.h2database</groupId>
   <artifactId>h2</artifactId>
  </dependency>

  <dependency>
   <groupId>org.apache.tomcat.embed</groupId>
   <artifactId>tomcat-embed-jasper</artifactId>
  </dependency>

  <dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>jstl</artifactId>
  </dependency>

 </dependencies>

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


</project>
 

Create the SpringBootHelloWorldApplication.java as follows-

package com.EXP;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RestController;

@RestController
@EnableAutoConfiguration
@SpringBootApplication
public class SpringBootHelloWorldApplication {

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

Create the Entity class as follows-

package com.EXP.model;

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

@Entity
public class Employee {
 @GeneratedValue(strategy = GenerationType.AUTO)
 @Id
 private long id;

 private String name;

 public String getName() {
  return name;
 }

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

 public String getDept() {
  return dept;
 }

 public void setDept(String dept) {
  this.dept = dept;
 }

 private String dept;

 @Override
 public String toString() {
  return "Employee [id=" + id + ", name=" + name + ", dept=" + dept + "]";
 }

}
 

The Controller we define methods to add Employee record and display employee records as list. Define the controller as follows-

package com.EXP.controllers;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

import com.EXP.data.EmployeeRepository;
import com.EXP.model.Employee;

@Controller
public class EmployeeController {

 @Autowired
 private EmployeeRepository employeeData;

 @RequestMapping(value = "/addNewEmployee.html", method = RequestMethod.POST)
 public String newEmployee(Employee employee) {

  employeeData.save(employee);
  return ("redirect:/list.html");

 }

 @RequestMapping(value = "/addNewEmployee.html", method = RequestMethod.GET)
 public ModelAndView addNewEmployee() {

  Employee emp = new Employee();
  return new ModelAndView("newEmployee", "form", emp);

 }

 @RequestMapping(value = "/listEmployees.html", method = RequestMethod.GET)
 public ModelAndView employees() {
  List<Employee> allEmployees = employeeData.findAll();
  return new ModelAndView("allEmployees", "employees", allEmployees);

 }

}

Next we define the EmployeeRepository which is an interface that extends the Spring Framework class JpaRepository. JpaRepository class is a generics and takes the following two parameters as arguments-

• What type of Object will this repository be working with- In our case Employee
• Id will be what type of object- Long(since id defined in the Employee class is long)

Thats the only configuration required for the repository class. The required operations like adding and retrieving employee details from DB will now be handled. 

package com.EXP.data;

import org.springframework.data.jpa.repository.JpaRepository;

import com.EXP.model.Employee;

public interface EmployeeRepository extends JpaRepository<Employee
   , Long> {

}

Define the newEmployee.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<h1>Employees page</h1>

<ul>
<c:forEach items="" var="employee">
   <li></li>
</c:forEach>
</ul>
 

Define the allEmployees.jsp

<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<html>
<body>
    <h1>Add new employee</h1>
        
    <form:form modelAttribute="form">
        <form:errors path="" element="div" />
        <div>
            <form:label path="name">Name</form:label>
            <form:input path="name" />
            <form:errors path="name" />
        </div>
        <div>
            <input type="submit" />
        </div>
    </form:form>
</body>
</html>
 

The application.properties will be as follows-

spring.mvc.view.prefix:/WEB-INF/jsp/
spring.mvc.view.suffix:.jsp

spring.datasource.url=jdbc:h2:file:./DB
spring.jpa.properties.hibernate.hbm2ddl.auto=update

Compile and the run the SpringBootHelloWorldApplication.java as a Java application.
Go to localhost:8080/addNewEmployee.html

Click add. We will be directed to the allEmployees.jsp