Adobe Flex with Struts 2 using HttpService

Using HttpService is the easiest way in which you can integrate Adobe Flex and Struts 2. As an example I will show you how you can create a registration form in Adobe Flex which calls a struts 2 action to create new users. Note that this example is very simple and for demonstration purposes. I am not adding any validation in flex and not even creating the users in a database. All I show you is how you can pass data between flex and struts.

First let me show you the steps you need to perform in Adobe Flex:

Step 1

Create the registration form in mxml:

<mx:Form label="Registration Form">
 <mx:FormHeading label="Registration Form">
 </mx:FormHeading>
 <mx:FormItem label="First Name">
  <mx:TextInput id="firstName">
  </mx:TextInput>
 </mx:FormItem>
 <mx:FormItem label="Last Name">
  <mx:TextInput id="lastName">
  </mx:TextInput>
 </mx:FormItem>
 <mx:FormItem label="Email">
   <mx:TextInput id="email">
  </mx:TextInput>
 </mx:FormItem>
 <mx:FormItem label="Username">
  <mx:TextInput id="username">
  </mx:TextInput>
 </mx:FormItem>
 <mx:FormItem label="Password">
  <mx:TextInput id="password" displayAsPassword="true">
  </mx:TextInput>
 </mx:FormItem>
 <mx:FormItem>
  <mx:Button label="Register" click="registerUser()"/>
 </mx:FormItem>
</mx:Form>

Step 2

Create the HttpService object:

<mx:HTTPService id="registerService" showBusyCursor="true" useProxy="false" url="register.action" resultFormat="e4x" method="POST" result="registerConfirmation(event)" fault="registerFailed(event)"/>

• register.action is the Struts 2 action that registers the user


• registerConfirmation(event) is the function that is called if the http service call is successful.


• registerFailed(event) is the function that is called if an error occurs. For example if the server is down. The event object gives you access to any xml/html that might be returned upon the call of the action.


• resultFormat specifies in which format you want to view the results. It can be text, xml or an object. There are 5 possible values for this field:
  
  • object - An XML object is returned and is parsed as a tree of ActionScript objects
  
  
  • xml - Returns literal XML in an XMLNode object
  
  
  • e4x - Returns literal XML that can be accessed using ECMAScript for XML(E4X) expressions.
  
  
  • flashvars - The result is text in flashvars format, value pairs separated by ampersands. Flex returns this result in an actionscript object
  
  
  • array - The result is XML that is returned in an Array even if there is only one top level node.
  
  

Step 3

Write the actionscript call to submit the form:

public function registerUser():void {
      var params:Object = { 'user.firstName': firstName.text,'user.lastName': lastName.text, 'user.email':email.text, 'user.password':password.text }; 
      this.registerService.send(params);
}

Step 4

Create registerConfirmation(). This method checks whether the registration was successful. We can know that by inspecting the XML that is returned.

private function registerConfirmation(event:ResultEvent):void {
        var xml:XML=XML(event.result); 
 if (xml != null && xml.item == true) {
  mx.controls.Alert.show("Registration Successful!");
 }
 else {
  mx.controls.Alert.show("The registration was not successful.");
 }
 }}

Step 5

If we can't call the action on the server because of some networking issue we also should give some feedback to the user.

   
/**
 * Display a message to the user explaining what went wrong
 */
private function registerFailed(event:FaultEvent):void {
 mx.controls.Alert.show(event.fault.message);
}

Now let's create our Struts 2 Action:

Step 1

Create RegisterAction.java

package uk.co.spltech.web.actions;

import uk.co.spltech.beans.User;

import com.opensymphony.xwork2.ActionSupport;

/**
 * Creates a new user
 * 
 * @author Armindo Cachada
 *
 */
public class RegisterAction extends ActionSupport {

 private User user;
 
 private Boolean success;
 
 public Boolean getSuccess() {
  return success;
 }

 public void setSuccess(Boolean success) {
  this.success = success;
 }

 public User getUser() {
  return user;
 }

 public void setUser(User user) {
  this.user = user;
 }

 /**
  * Registers a user
  * 
  * @return
  */
 public String register() {
  System.out.println("Checking user");
  if ( this.getUser()!= null) {
   User u = this.getUser();
   if (u.getEmail()!= null && !u.getEmail().equals("") && u.getPassword()!= null 
     && !u.getPassword().equals("") ) {
    System.out.println("Successfully registered user with email=" + u.getEmail());
    this.success=true;
   }
   else {
    this.success=false;
    System.out.println("Error registering user");
   }
  }
  else {
   this.success=false;
   System.out.println("Error registering user");
  }
  
  return SUCCESS;

 }
 
}

Step 2

Add action name='register' to struts.xml

<package name="user" extends="struts-default">
        <action name="register" method="register" class="uk.co.spltech.web.actions.RegisterAction">
           <result type="xslt">   <param name="exposedValue">{success}</param></result>
        </action>
</package>

Source for "Adobe Flex with Struts 2 using HttpService" Example

To compile this example you will need to copy the following libraries to the lib folder:

commons-fileupload-1.2.1.jar
commons-io-1.3.2.jar
commons-logging.jar
freemarker-2.3.13.jar
ognl-2.6.11.jar
struts2-core-2.1.6.jar
xwork-2.1.2.jar
struts2-convention-plugin-2.1.6.jar