Posted by  on May 2, 2015 in Ajax, AngularJS, Struts-2 | 5 comments
In this post, we will learn to implement AJAX calls from a JSP page to a Struts 2 Action class using AngularJS and update the same JSP page back with the Json response from the Struts 2.

Library Required


Since Angular can send and receive only in json format, to handle it you need struts2-json-plugin-2.x.x.jar. This plugin allows you to serialize the Action class attribute which has getter and setter into a JSON object.

How to use?


First of all create a “Dynamic Web Project” in Eclipse and download the AngularJS library and place in js folder of eclipse work-space, and refer this files in the head section in the jsp, this file is responsible for the AJAX call made to the Struts2 and for updating the response back in the JSP.

Jsp Page


File: index.jsp
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>AJAX with Struts 2 using AngularJS</title>
<script type="text/javascript" src="js/angular.min.js"></script>
<script>
var app = angular.module('myApp', []);
function MyController($scope, $http) {
$scope.getDataFromServer = function() {
        $http.get("angularAction").success(
                function(data, status, headers, config) {
                        $scope.person = data;
                }).error(function(data, status, headers, config) {
                                // called asynchronously if an error occurs
                                // or server returns response with an error status.
        });
};
};
</script>
</head>
<body>
<div data-ng-app="myApp">
        <div data-ng-controller="MyController">
                <button data-ng-click="getDataFromServer()">
                Fetch data from server
                </button>
                <p>First Name : {{person.firstName}}</p>
                <p>Last Name : {{person.lastName}}</p>
        </div>
</div>
</body>
</html>

HTML – Data Binding


We can display JSON data values in jsp by using their attributes in expressions like {{person.firstName}}, {{person.lastName}} etc.. Here the id=”ng-app” is most important for Internet Explorer browser data binding.

ng-controller
Specifies a JavaScript controller class that evaluates HTML expressions.
ng-click
Angular on click event

Model class


package com.model;
public class PersonData {

        private String firstName;
        private String lastName;
        
        // Create Getters and Setters 
}

Recommended Reading:

Action Class


In action class you need to create instance variables and its respective getter and setter methods. Here all the variables that have a setter can be set to the values received as parameters from AngularJs and all the variables that have a getter method can be retrieved in the AngularJs code.
package com.action;
import com.model.PersonData;
import com.opensymphony.xwork2.Action;
public class AngularAction implements Action {

        private PersonData personData = new PersonData();

        public String execute() {

                personData.setFirstName("Mohaideen");
                personData.setLastName("Jamil");
                return SUCCESS;
        }

        public PersonData getPersonData() {
                return personData;
        }

        public void setPersonData(PersonData personData) {
                this.personData = personData;
        }
}

Code Explanation


When the user clicks on “Fetch data from server” button, button click event is fired via angularJS “ng-click” directive and the ‘http’ function executes the Ajax GET request on the Servlet.

struts.xml


Since the response needed by AngularJs is of type json, so we need to convert the PersonData objects to json strings, for this you need to configure Action class in struts.xml such that it returns a json object. This configuration is as follows:
Create a package in struts.xml file, which extend json-default and specify the result type of your action class inside this package to be json. The json-default package contains an interceptor and the result type configuration for JSON requests and responses.
<struts>
<package name="default" extends="json-default">
    <action name="angularAction" class="com.action.AngularAction">
        <result type="json">
          <param name="root">personData</param>
          <param name="excludeNullProperties">true</param>
          <param name="noCache">true</param>
        </result>
    </action>
</package>
</struts>

Note: json-default package extends struts-default
Please read the Struts 2 JSON plugin documentation for more details.


Web.xml


<display-name>Struts2</display-name>
<filter>
  <filter-name>struts2</filter-name>
  <filter-class>
    org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
  </filter-class>
</filter>
<filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>
<welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

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  • How to Call Struts2 action from java script


    • Demo


    Once you done with above steps then Right click on project –> Run As –> Run on Server
    (Note: I have used tomcat server to run this application. If you are not sure how to configure tomcat server in eclipse please follow this link).
    `


    Click button: Fetch data from server to pass HTTP request using angularJS where Java servlet will return data as below:
    download