AJAX

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Both Struts 1 and Struts 2 can return any type of response. We are not limited to forwarding to a server page. In Struts 1, you can just do something like:

Code Block
java
{
 response.setContentType("text/html");
 PrintWriter out = response.getWriter();
 out.println("Hello World!  This is an AJAX response from a Struts Action.");
 out.flush();
 return null;
}

In Struts 2, we can do the same thing with a Stream result.

Note
titleThere are easier ways!

Using a Struts 2 plugin (e.g., JSON plugin, jQuery plugin, etc.) is, in general, preferred to writing the response directly from within an action. See sections following this for further details.

Code Block
titleStruts 2 Stream result Action
langjava
package actions;

import java.io.InputStream;
 import java.io.StringBufferInputStream;
 import com.opensymphony.xwork2.ActionSupport;

public class TextResult extends ActionSupport  {
    private InputStream inputStream;
    public InputStream getInputStream() {
        return inputStream;
    }

    public String execute() throws Exception {
        inputStream = new StringBufferInputStreamByteArrayInputStream(
   "Hello World! This is a text string response from a Struts 2 Action.".getBytes("UTF-8"));
        return SUCCESS;
    }
}
Code Block
titleStruts 2 Configuring the TextResult Action
langxml
<action name="text-result" class="actions.TextResult">
    <result type="stream">
        <param name="contentType">text/html</param>
        <param name="inputName">inputStream</param>
    </result>
</action>

(tick) Struts 2 can also return a JSON (JavaScript Object Notation) response, using a plugin.

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  • Ajax Parts - The AjaxParts Taglib (APT) is a component of the Java Web Parts (JWP) project (http://javawebparts.sourceforge.net) that allows for 100% declarative (read: no Javascript coding required!) AJAX functionality within a Java-based webapp.
  • Dojo - The Ajax Tags Dojo Plugin was represented as a theme for Struts 2.0. For Struts 2.1, the Dojo tags are bundled as a plugin.
  • YUI - The Yahoo User Interface (YUI) Plugin has only a few tags are available so far, but the YUI tags tend to be easier to use than the Dojo versions.
  • jQuery - The jQuery Plugin provide ajax functionality and UI Widgets an JavaScript Grid based on the jQuery javascript framework..

Other Ajax Plugins

  • Ajax File Upload - With the Ajax File Upload Plugin we can upload a file to the server and asynchronously monitor its progress.
  • GWT - The Google Web Toolkit Plugin exposes Struts 2 actions to the GWT RPC mechanism.
  • JSON - The JSON Plugin serializes Actions properties into JSON, making it easy to respond to JavaScript requests.

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