How to develop Rest Web Service using @RestController - Spring Framework

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What Will I Learn?

In this tutorial, we will learn about how we can develop Rest web API or Services using @RestController annotation in Spring framework and how you can call the web services using ARC Client

Rest Web services
Get JSON data from Rest web Services using ARC or Web Browser

Requirements

Eclipse IDE (Juno or above)
JDK 1.7 or above
Tomcat Server 7 or above
Spring and jackson jar files
Web Browser Chrome or Firefox

Difficulty

Basic

Tutorial Contents

Application Configuration wit Spring Framework

Now we configure the web application with sping framework to creating @restController

configuring web.xml file
First of all paste all jar files into lib folder
Here we configure web.xml file to run application application

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/spring-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
  </servlet>  
  <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <url-pattern>/</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
        <welcome-file></welcome-file>
  </welcome-file-list>  
</web-app>

Screenshot (103).png

configuring spring-servlet.xml
Basic configuration of databse, view resolver and sessionfactory

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:p="http://www.springframework.org/schema/p" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-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/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

<context:property-placeholder location="classpath:resources/database.properties" />
    <context:component-scan base-package="com.blog" />

    <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/" />
        <property name="suffix" value=".jsp" />
    </bean>
    ```

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="annotatedClasses">
        <list>
            <value>com.blog.model.Users</value>
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">${hibernate.dialect}</prop>
            <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
            <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>             
        </props>
    </property>
</bean>


</beans>

Screenshot (104).png

Creating RestController
Here we create RestControler java file and write code for populating list and converlist from ArrayList to json and this controler return json object string

package com.blog.restwebservice;
import java.io.IOException;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import com.blog.bean.QuestionsBean;
import beans.ConvertDateFormat;
import beans.ListToJsonObject;
import beans.Sudent;
import com.blog.model.Questions;
import com.blog.service.QuestionsService;

@RestController
@RequestMapping("/yayayaa")
public class RestWebServiceController {
    @Autowired(required=false)
    private QuestionsService questionsService;  
    ListToJsonObject listtojson = new ListToJsonObject();
    ConvertDateFormat fmt = new ConvertDateFormat();    
    @RequestMapping(method = RequestMethod.GET)
    public @ResponseBody String listQuestionsss() throws JsonGenerationException, JsonMappingException, IOException, ParseException {                       
        List<Sudent> list = listofStudents();   
        String json = new ObjectMapper().writeValueAsString(list);
        return json;
    }       
    List<Sudent> list = new ArrayList<Sudent>();
    public List<Sudent> listofStudents()
    {
        list.add(new Sudent(1,20,"Rahul","Whatever","rahul@gmail.com"));
        list.add(new Sudent(2,21,"Ramesh","Whatever","ramesh@gmail.com"));
        list.add(new Sudent(3,22,"Shyam","Whatever","shyam@gmail.com"));
        list.add(new Sudent(4,23,"Ram","Whatever","ram@gmail.com"));
        list.add(new Sudent(5,24,"Krishna","Whatever","krishna@gmail.com"));
        list.add(new Sudent(6,25,"Jacop","Whatever","jacop@gmail.com"));        
        return list;
    }
}