How to integrate Cross Origin Resource Sharing wit

Question

I have a Simple Web Service returning JSON data.

The User Class (com.bargadss.SpringService.Domain) is The POJO class containing

user_ID, firstName, lastName, eMail

The UserService class (com.bargadss.SpringService.DAO) two major operation

1. getAllUser() -> Queries the DB to Select all Users from User Table and returns List{User}
2. getUserById(int user_ID) -> Queries the DB to Select a specific user based on ID

The SpringServiceController (com.bargadss.SpringService.Controller) is as follows :

package com.bargadss.SpringService.Controller;

import java.util.List;

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;

import com.bargadss.SpringService.DAO.UserService;
import com.bargadss.SpringService.Domain.User;


@RestController
@RequestMapping("/service/user/")
public class SpringServiceController {
 UserService userService=new UserService();

 @RequestMapping(value = "/{id}", method = RequestMethod.GET,headers="Accept=application/json")
 public User getUser(@PathVariable int id) {        
  User user=userService.getUserById(id);
  return user;
 }

 @RequestMapping(method = RequestMethod.GET,headers="Accept=application/json")
 public List<User> getAllUsers() {   
  List<User> users=userService.getAllUsers();
  return users;
 }
}

The ListUserController (com.bargadss.SpringService.Controller) is as follows :

package com.bargadss.SpringService.Controller;

import java.util.LinkedHashMap;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.servlet.ModelAndView;

import com.bargadss.SpringService.Domain.User;


@Controller
public class ListUserController {

@RequestMapping("/listUsers")
public ModelAndView listUsers() { 
    RestTemplate restTemplate = new RestTemplate();
    String url="http://localhost:8080/SpringServiceWithRESTAndJSONExample/service/user/";    
    List<LinkedHashMap> users=restTemplate.getForObject(url, List.class);
    return new ModelAndView("listUsers", "users", users);
}

@RequestMapping("/dispUser/{userid}")
public ModelAndView dispUser(@PathVariable("userid") int userid) { 
    RestTemplate restTemplate = new RestTemplate();
    String url="http://localhost:8080/SpringServiceWithRESTAndJSONExample/service/user/{userid}";
    User user=restTemplate.getForObject(url, User.class,userid);
    return new ModelAndView("dispUser", "user", user);
 }

}

The CorsFilter (com.bargadss.CORS) is as follows :

package com.bargadss.CORS;

import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.filter.OncePerRequestFilter;


public class CorsFilter extends OncePerRequestFilter{

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {
    if (request.getHeader("Access-Control-Request-Method") != null && "OPTIONS".equals(request.getMethod())) {
        // CORS "pre-flight" request
        response.addHeader("Access-Control-Allow-Origin", "*");
        response.addHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
        response.addHeader("Access-Control-Allow-Headers", "Content-Type");
        response.addHeader("Access-Control-Max-Age", "1800");//30 min
    }
    filterChain.doFilter(request, response);
}

}

The web.xml is as follows :

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xmlns="http://java.sun.com/xml/ns/javaee" 
     xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" 
     id="WebApp_ID" version="3.0">
<display-name>SpringServiceWithRESTAndJSONExample</display-name>

<servlet>
   <servlet-name>rest</servlet-name>
  <servlet-class>
         org.springframework.web.servlet.DispatcherServlet
  </servlet-class>
  <load-on-startup>1</load-on-startup>
</servlet>

<servlet>
  <servlet-name>jsp</servlet-name>
  <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
</servlet>

<servlet-mapping>
  <servlet-name>rest</servlet-name>
  <url-pattern>/*</url-pattern>
</servlet-mapping>

<servlet-mapping>
 <servlet-name>jsp</servlet-name>
 <url-pattern>/WEB-INF/jsp/*</url-pattern>
</servlet-mapping>

<filter>
  <filter-name>cors</filter-name>
  <filter-class>com.bargadss.CORS.CorsFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>cors</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>

The Web Service when being invoked by AngularJS from another Web Server returns Error referring to Cross Origin Resource Sharing problem !!!

What Changes must be performed in the Controller side to eliminate the error ?

Is there any changes necessary to be done at the AngularJS side to avoid this situation ?

Answer 1

Check the cors-filter

Download cors-filter-2.1.2.jar and java-property-utils-1.9.1.jar.

mvn dependency

<dependency>
    <groupId>com.thetransactioncompany</groupId>
    <artifactId>cors-filter</artifactId>
    <version>2.1.2</version>
</dependency>
<dependency>
  <groupId>com.thetransactioncompany</groupId>
  <artifactId>java-property-utils</artifactId>
  <version>1.9.1</version>
</dependency>

and in web.xml

<filter>
    <filter-name>CORS</filter-name>
    <filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
</filter>
 <filter-mapping>
        <filter-name>CORS</filter-name>
    <url-pattern>/*</url-pattern>
 </filter-mapping>