Spring Restful Web Services Json Example

Table of Contents [hide]

Spring application configuration:
Create bean class
Create controller
- Run the application

In this post, we will see Spring Restful web services json example.

In previous post, we have created a very simple Spring Restful web services which returns plain text. In this post, we will see Spring Restful web services which will return json as example. If you want complete integration with hibernate and mysql, you can go through Spring Restful hibernate mysql example.

Here are steps to create a simple Spring Restful web services which will return json.
1) Create a dynamic web project using maven in eclipse.

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

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

package org.arpit.java2blog.bean;

public class Country{

    int id;
    String countryName;

    public Country(int i, String countryName) {
        super();
        this.id = i;
        this.countryName = countryName;
    }
    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;
    }

}

package org.arpit.java2blog.bean;

public class Country{

int id;

String countryName;

public Country(int i, String countryName) {

super();

this.id = i;

this.countryName = countryName;

}

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;

}

Create controller

6) Create a controller named “CountryController.java”

package org.arpit.java2blog.controller;

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

import org.arpit.java2blog.bean.Country;
import org.springframework.web.bind.annotation.PathVariable;
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 {

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

    @RequestMapping(value = "/country/{id}", method = RequestMethod.GET,headers="Accept=application/json")
    public Country getCountryById(@PathVariable int id)
    {
        List listOfCountries = new ArrayList();
        listOfCountries=createCountryList();

        for (Country country: listOfCountries) {
            if(country.getId()==id)
                return country;
        }

        return null;
    }

    // Utiliy method to create country list.
    public List createCountryList()
    {
        Country indiaCountry=new Country(1, "India");
        Country chinaCountry=new Country(4, "China");
        Country nepalCountry=new Country(3, "Nepal");
        Country bhutanCountry=new Country(2, "Bhutan");

        List listOfCountries = new ArrayList();
        listOfCountries.add(indiaCountry);
        listOfCountries.add(chinaCountry);
        listOfCountries.add(nepalCountry);
        listOfCountries.add(bhutanCountry);
        return listOfCountries;
    }
}

package org.arpit.java2blog.controller;

import java.util.ArrayList;

import java.util.List;

import org.arpit.java2blog.bean.Country;

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

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 {

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

public List getCountries()

{

List listOfCountries = new ArrayList();

listOfCountries=createCountryList();

return listOfCountries;

}

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

public Country getCountryById(@PathVariable int id)

{

List listOfCountries = new ArrayList();

listOfCountries=createCountryList();

for (Country country: listOfCountries) {

if(country.getId()==id)

return country;

}

return null;

}

// Utiliy method to create country list.

public List createCountryList()

{

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

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

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

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

List listOfCountries = new ArrayList();

listOfCountries.add(indiaCountry);

listOfCountries.add(chinaCountry);

listOfCountries.add(nepalCountry);

listOfCountries.add(bhutanCountry);

return listOfCountries;

}

@PathVariable: Used to inject values from the URL into a method parameter.This way you inject id in getCountryById method.

We are not providing any view information in springrest-servlet.xml as we do in Spring MVC. If we need to directly get resource from controller, we need to return @ResponseBody as per Spring 3 but with Spring 4, we can use @RestController for that.
In spring 4.0, we can use @RestController which is combination of @Controller + @ResponseBody.

@RestController = @Controller + @ResponseBody

@RestController = @Controller + @ResponseBody

6) It ‘s time to do maven build.

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

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

Run the application

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

Select apache tomcat and click on finish

When you run the application, you might get this kind of warning

Mar 26, 2016 1:45:51 AM org.springframework.web.servlet.PageNotFound noHandlerFound
WARNING: No mapping found for HTTP request with URI [/SpringRestfulWebServicesWithJSONExample/] in DispatcherServlet with name 'SpringRestfulWebServicesWithJSONExample'

Mar 26, 2016 1:45:51 AM org.springframework.web.servlet.PageNotFound noHandlerFound

WARNING: No mapping found for HTTP request with URI [/SpringRestfulWebServicesWithJSONExample/] in DispatcherServlet with name 'SpringRestfulWebServicesWithJSONExample'

Please ignore above warning. When you start application, you have below URL if you have not provided start page:
http://localhost:8080/SpringRestfulWebServicesWithJSONExample/

As we have used DispatcherServlet in web.xml, this request goes to spring DispatcherServlet and it did not find corresponding mapping in controller , hence you get that warning.

9) Test your REST service under: “http://localhost:8080/SpringRestfulWebServicesWithJSONExample/countries”.

You will get following output:

10) Now pass country id as parameter to url.
“http://localhost:8080/SpringRestfulWebServicesWithJSONExample/country/2”.

Download

click to begin

20KB .zip

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

That’s all about Spring Restful web services json example.

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Comments

Sarjaycs says:

October 27, 2015 at 5:05 pm

Best and simple way of implementing Restful webservice. Very useful

Thanks

Damian says:

November 11, 2015 at 2:11 pm

Hello, I have one problem with this example…

lis 11, 2015 3:09:30 PM org.springframework.web.servlet.PageNotFound noHandlerFound
WARNING: No mapping found for HTTP request with URI [/SpringRestfulWebServicesWithJSONExample/countries] in DispatcherServlet with name 'springrest'

1. Noah says:
  
  January 29, 2016 at 1:21 am
  
  I think you might have copied over the package value of base-package=”org.arpit.java2blog.controller” /> in springrest-servlet.xml. You need to put in your own package name instead… I fell victim to this error as well and it took me a few too many minutes to find the issue…
  
saurabh says:

February 1, 2016 at 6:37 pm

you have said , to put the code in class path,, where is this class path

1. arpitmandliya says:
  
  February 1, 2016 at 6:43 pm
  
  Are you using maven for running above project? If yes, then maven will automatically fetch required library and will put it in the build path.
  Let me know if you need more help on this. Thanks for asking
  
saurabh says:

February 2, 2016 at 8:42 am

hi i am getting this error now:-

Feb 02, 2016 2:11:24 PM org.springframework.web.servlet.PageNotFound noHandlerFound
WARNING: No mapping found for HTTP request with URI [/mavenWebApp/] in DispatcherServlet with name 'springrest'

my app name is mavenWebAppp

1. arpitmandliya says:
  
  February 2, 2016 at 8:48 am
  
  please check springrest-servlet.xml in /WEB-INF/ folder once
  you need to change context:component-scan if you want to use different package for spring to search for controller.
  let me know if you need more help on it.
  
Brian says:

February 29, 2016 at 4:38 am

works fine, thank you!

Brian says:

March 1, 2016 at 1:26 am

can you tell how to produce xml format using a similar method to this json way?

Archit says:

March 18, 2016 at 5:50 pm

Works fine, thank you so much !!

Ghana says:

April 15, 2016 at 9:25 am

Works Fine, But how to send json response back (http POST) not discussed.

1. arpitmandliya says:
  
  April 15, 2016 at 7:19 pm
  
  Please go through below link for post operation : https://www.java2blog.com/2016/04/spring-restful-w…
  
Yuri says:

September 10, 2016 at 12:09 pm

If not working fine, “No mapping found for HTTP request with URI ” remember, RUN THE MAVEN UPDATE BITCH!

I was with this problem and thus resolved, rs. THANKS alot

ameen mohammad says:

September 29, 2016 at 12:58 pm

Dear Author,

Impressed your article has worked as one shot operation.
Just downloaded, Built with Maven, updated Maven, Run on Tomcat Server.
Perfect example for Rest WebService.

Thank you so much.

Regards,
Ameen Mohammad

Ankit joshi says:

January 9, 2017 at 8:17 am

ONE problem I encountered was Junit Dependency was not getting resolve so application was not working. may be the version provided in the example is deprecated now. I removed that dependency and it worked.
one more thing I did wrong was not changes the import package name for bean class in controller class. I used as is given here ” org.arpit.java2blog.bean.Country” which was wrong according to my folder structure. I know this was silly mistake but even the eclipse was not showing any error.

BTW thanks arpit . good article.

1. kiran says:
  
  March 6, 2018 at 9:05 am
  
  yah good
  
jagan says:

April 23, 2017 at 3:56 pm

Dear Author,
I impressed your code, but i am getting small error.
org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource.

any help highly appreciated

Regards

arjun says:

October 11, 2017 at 3:32 pm

Great Thanks

hitesh marathe says:

December 16, 2019 at 3:12 pm

You don’t know how much you do beneficence on me to provide this solution, you know I have been searching this answer for 5 days. thanks a lot