Spring Restful web services CRUD example

Table of Contents

Web service Tutorial Content:
Spring application configuration:
Get method
- Post method
- Put Method
Delete method
Project structure:

In this post, we are going see Spring Restful web services CRUD example.

Web service Tutorial Content:

In previous post, we have already seen Spring Restful web services which returns json as response.In this post, we will extend same example and create Restful web services which will provide CRUD(Create, read, update and delete) operation example.If you want complete integration with hibernate and mysql, you can go through Spring Restful hibernate mysql example.

We will use following annotations for CRUD operation.

Method	Description
Get	It is used to read resource
Post	It is used to create new resource. It is not idempotent method
Put	It is generally used to update resource.It is idempotent method
Delete	It is used to delete resource

Idempotent means result of multiple successful request will not change state of resource after initial application
For example :
Delete is idempotent method because when you first time use delete, it will delete the resource (initial application) but after that, all other request will have no result because resource is already deleted.

Post is not idempotent method because when you use post to create resource , it will keep creating resource for each new request, so result of multiple successful request will not be same.

Source code:

Download source code:Spring Restful web services CRUD example

Here are steps to create a Spring Restful web services which will provide CRUD opertion.

1) Create a dynamic web project using maven in eclipse named “SpringRestfulWebServicesCRUDExample”

Maven dependencies

2) We need to add Jackson json utility in the classpath.


<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
             <version>2.4.1</version>
 </dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

Spring will load Jackson2JsonMessageConverter into its application context automatically. Whenever you request resource as json with accept headers=”Accept=application/json”, then Jackson2JsonMessageConverter comes into picture and convert resource to json format.

Now change pom.xml as follows:
pom.xml


<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.arpit.java2blog</groupId>
  <artifactId>SpringRestfulWebServicesWithJSONExample</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>SpringRestfulWebServicesWithJSONExample Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>javax.servlet-api</artifactId>
   <version>3.1.0</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-core</artifactId>
   <version>${spring.version}</version>
  </dependency>
  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-webmvc</artifactId>
   <version>${spring.version}</version>
  </dependency>
   <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
             <version>2.4.1</version>
        </dependency>
 </dependencies>
 <build>
  <finalName>SpringRestfulWebServicesWithJSONExample</finalName>

  <plugins>
   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.1</version>
    <configuration>
     <source>${jdk.version}</source>
     <target>${jdk.version}</target>
    </configuration>
   </plugin>
  </plugins>

 </build>
 <properties>
  <spring.version>4.2.1.RELEASE</spring.version>
  <jdk.version>1.7</jdk.version>
 </properties>
</project>

<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/maven-v4_0_0.xsd">

<groupId>com.arpit.java2blog</groupId>

<artifactId>SpringRestfulWebServicesWithJSONExample</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>SpringRestfulWebServicesWithJSONExample Maven Webapp</name>

<url>http://maven.apache.org</url>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<groupId>javax.servlet</groupId>

<artifactId>javax.servlet-api</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-core</artifactId>

<version>${spring.version}</version>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-webmvc</artifactId>

<version>${spring.version}</version>

</dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

</dependencies>

<build>

<finalName>SpringRestfulWebServicesWithJSONExample</finalName>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-compiler-plugin</artifactId>

<source>${jdk.version}</source>

<target>${jdk.version}</target>

</configuration>

</plugin>

</plugins>

</build>

<spring.version>4.2.1.RELEASE</spring.version>

<jdk.version>1.7</jdk.version>

</properties>

</project>

Spring application configuration:

3) Change web.xml as below:


<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
 <servlet-name>springrest</servlet-name>
 <servlet-class>
  org.springframework.web.servlet.DispatcherServlet
 </servlet-class>
 <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
 <servlet-name>springrest</servlet-name>
 <url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>

<!DOCTYPE web-app PUBLIC

"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

"http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>

<display-name>Archetype Created Web Application</display-name>

<servlet-name>springrest</servlet-name>

<servlet-class>

org.springframework.web.servlet.DispatcherServlet

</servlet-class>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>springrest</servlet-name>

<url-pattern>/</url-pattern>

</servlet-mapping>

</web-app>

4) create a xml file named springrest-servlet.xml in /WEB-INF/ folder.
Please change context:component-scan if you want to use different package for spring to search for controller.Please refer to spring mvc hello world example for more understanding.


<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

 <mvc:annotation-driven/>
<context:component-scan base-package="org.arpit.java2blog.controller" />

</beans>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

<mvc:annotation-driven/>

<context:component-scan base-package="org.arpit.java2blog.controller" />

</beans>

Create bean class

4) Create a bean name “Country.java” in org.arpit.java2blog.bean.


package org.arpit.java2blog.bean;

public class Country{

    int id;
    String countryName;
    long population;

    public Country() {
        super();
    }
    public Country(int i, String countryName,long population) {
        super();
        this.id = i;
        this.countryName = countryName;
        this.population=population;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getCountryName() {
        return countryName;
    }
    public void setCountryName(String countryName) {
        this.countryName = countryName;
    }
    public long getPopulation() {
        return population;
    }
    public void setPopulation(long population) {
        this.population = population;
    }

}

package org.arpit.java2blog.bean;

public class Country{

int id;

String countryName;

long population;

public Country() {

super();

}

public Country(int i, String countryName,long population) {

super();

this.id = i;

this.countryName = countryName;

this.population=population;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getCountryName() {

return countryName;

}

public void setCountryName(String countryName) {

this.countryName = countryName;

}

public long getPopulation() {

return population;

}

public void setPopulation(long population) {

this.population = population;

}

Create Controller

5) Create a controller named “CountryController.java” in package org.arpit.java2blog.controller


package org.arpit.java2blog.controller;

import java.util.List;
import org.arpit.java2blog.bean.Country;
import org.arpit.java2blog.service.CountryService;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CountryController {

    CountryService countryService = new CountryService();

    @RequestMapping(value = "/countries", method = RequestMethod.GET, headers = "Accept=application/json")
    public List getCountries() {
        List listOfCountries = countryService.getAllCountries();
        return listOfCountries;
    }

    @RequestMapping(value = "/country/{id}", method = RequestMethod.GET, headers = "Accept=application/json")
    public Country getCountryById(@PathVariable int id) {
        return countryService.getCountry(id);
    }

    @RequestMapping(value = "/countries", method = RequestMethod.POST, headers = "Accept=application/json")
    public Country addCountry(@RequestBody Country country) {
        return countryService.addCountry(country);
    }

    @RequestMapping(value = "/countries", method = RequestMethod.PUT, headers = "Accept=application/json")
    public Country updateCountry(@RequestBody Country country) {
        return countryService.updateCountry(country);

    }

    @RequestMapping(value = "/country/{id}", method = RequestMethod.DELETE, headers = "Accept=application/json")
    public void deleteCountry(@PathVariable("id") int id) {
        countryService.deleteCountry(id);

    }
}

package org.arpit.java2blog.controller;

import java.util.List;

import org.arpit.java2blog.bean.Country;

import org.arpit.java2blog.service.CountryService;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

public class CountryController {

CountryService countryService = new CountryService();

@RequestMapping(value = "/countries", method = RequestMethod.GET, headers = "Accept=application/json")

public List getCountries() {

List listOfCountries = countryService.getAllCountries();

return listOfCountries;

}

@RequestMapping(value = "/country/{id}", method = RequestMethod.GET, headers = "Accept=application/json")

public Country getCountryById(@PathVariable int id) {

return countryService.getCountry(id);

}

@RequestMapping(value = "/countries", method = RequestMethod.POST, headers = "Accept=application/json")

public Country addCountry(@RequestBody Country country) {

return countryService.addCountry(country);

}

@RequestMapping(value = "/countries", method = RequestMethod.PUT, headers = "Accept=application/json")

public Country updateCountry(@RequestBody Country country) {

return countryService.updateCountry(country);

}

@RequestMapping(value = "/country/{id}", method = RequestMethod.DELETE, headers = "Accept=application/json")

public void deleteCountry(@PathVariable("id") int id) {

countryService.deleteCountry(id);

}

Create Service class

6) Create a class CountryService.java in package org.arpit.java2blog.service
It is just a helper class which should be replaced by database implementation. It is not very well written class, it is just used for demonstration.


import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.arpit.java2blog.bean.Country;

/*
 * It is just a helper class which should be replaced by database implementation.
 * It is not very well written class, it is just used for demonstration.
 */
public class CountryService {

    static HashMap<Integer,Country> countryIdMap=getCountryIdMap();

    public CountryService() {
        super();

        if(countryIdMap==null)
        {
            countryIdMap=new HashMap<Integer,Country>();
            // Creating some objects of Country while initializing
            Country indiaCountry=new Country(1, "India",10000);
            Country chinaCountry=new Country(4, "China",20000);
            Country nepalCountry=new Country(3, "Nepal",8000);
            Country bhutanCountry=new Country(2, "Bhutan",7000);

            countryIdMap.put(1,indiaCountry);
            countryIdMap.put(4,chinaCountry);
            countryIdMap.put(3,nepalCountry);
            countryIdMap.put(2,bhutanCountry);
        }
    }

    public List getAllCountries()
    {
        List countries = new ArrayList(countryIdMap.values());
        return countries;
    }

    public Country getCountry(int id)
    {
        Country country= countryIdMap.get(id);
        return country;
    }
    public Country addCountry(Country country)
    {
        country.setId(getMaxId()+1);
        countryIdMap.put(country.getId(), country);
        return country;
    }

    public Country updateCountry(Country country)
    {
        if(country.getId()<=0)
            return null;
        countryIdMap.put(country.getId(), country);
        return country;

    }
    public void deleteCountry(int id)
    {
        countryIdMap.remove(id);
    }

    public static HashMap<Integer, Country> getCountryIdMap() {
        return countryIdMap;
    }

    // Utility method to get max id
    public static int getMaxId()
    { int max=0;
    for (int id:countryIdMap.keySet()) {
        if(max<=id)
            max=id;

    }
    return max;
    }
}

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import org.arpit.java2blog.bean.Country;

* It is just a helper class which should be replaced by database implementation.

* It is not very well written class, it is just used for demonstration.

public class CountryService {

static HashMap<Integer,Country> countryIdMap=getCountryIdMap();

public CountryService() {

super();

if(countryIdMap==null)

{

countryIdMap=new HashMap<Integer,Country>();

// Creating some objects of Country while initializing

Country indiaCountry=new Country(1, "India",10000);

Country chinaCountry=new Country(4, "China",20000);

Country nepalCountry=new Country(3, "Nepal",8000);

Country bhutanCountry=new Country(2, "Bhutan",7000);

countryIdMap.put(1,indiaCountry);

countryIdMap.put(4,chinaCountry);

countryIdMap.put(3,nepalCountry);

countryIdMap.put(2,bhutanCountry);

}

public List getAllCountries()

{

List countries = new ArrayList(countryIdMap.values());

return countries;

}

public Country getCountry(int id)

{

Country country= countryIdMap.get(id);

return country;

}

public Country addCountry(Country country)

{

country.setId(getMaxId()+1);

countryIdMap.put(country.getId(), country);

return country;

}

public Country updateCountry(Country country)

{

if(country.getId()<=0)

return null;

countryIdMap.put(country.getId(), country);

return country;

}

public void deleteCountry(int id)

{

countryIdMap.remove(id);

}

public static HashMap<Integer, Country> getCountryIdMap() {

return countryIdMap;

}

// Utility method to get max id

public static int getMaxId()

{ int max=0;

for (int id:countryIdMap.keySet()) {

if(max<=id)

max=id;

}

return max;

}

7) It ‘s time to do maven build.

Right click on project -> Run as -> Maven build

8) Provide goals as clean install (given below) and click on run

Run the application

9) Right click on project -> run as -> run on server

Select apache tomcat and click on finish

10) We will test this application in postman , UI based client for testing restful web applications. It is chrome plugin. Launch postman.If you want java based client, then you can also use how to send get or post request in java.

Get method

11) Test your get method Spring REST service
URL :“http://localhost:8080/SpringRestfulWebServicesCRUDExample/countries”.

You will get following output:

Post method

12) Post method is used to create new resource. Here we are adding new Country England to country list, so you can see we have used new country json in post body.
URL: “http://localhost:8080/SpringRestfulWebServicesCRUDExample/countries”.

Use get method to check if above country have been added to country list.

Put Method

13) Put method is used to update resource. Here will update population of nepal using put method.
We will update country json in body of request.
URL : “http://localhost:8080/SpringRestfulWebServicesCRUDExample/countries”

Use get method to check population of nepal.

Delete method

14) Delete method is used to delete resource.We will pass id of country which needs to be deleted as PathParam. We are going delete id:4 i.e. china to demonstrate delete method.

URL : “http://localhost:8080/SpringRestfulWebServicesCRUDExample/country/4”

Use get method to check country list.

As you can see, we have deleted country with id 4 i.e. china

Project structure:

We are done with Spring Restful web services json CRUD example. If you are still facing any issue, please comment.

Was this post helpful?

Let us know if this post was helpful. Feedbacks are monitored on daily basis. Please do provide feedback as that\'s the only way to improve.

Comments

Myna says:

July 11, 2016 at 9:33 pm

Perfect! Awesome! Thank you sooo much!!

Asraar says:

July 27, 2016 at 1:47 pm

Hi,
Great work !!!

Ravi says:

August 29, 2016 at 6:57 pm

Really helpfull

sivakumar says:

December 20, 2016 at 1:33 pm

super…

vijay says:

May 2, 2017 at 12:44 pm

simply great tutorial …
thanks 🙂

Chandra says:

March 6, 2018 at 11:18 am

Nice 🙂

sagar says:

March 23, 2018 at 11:50 am

Awesome example thanks for sharing this example to us its helps alot to me….thanks onces again

Amit says:

April 19, 2020 at 11:19 pm

Thank you sooo much