Struts 2: how to set response for ajax function call?

[Ramesh Babu Essampalli]

i am calling an ajax function from jsp page. The execute method of action class is getting called.

now, i want to set response parameter in execute methood for xmlhttp.responseText in ajax function call. i implemented ServletResponseAware and in setServletResponse method i set response parameter. but the response param value is over-written by return page of execute method. please suggest me a way to set response param.

please find below my ajaxcall in javascript:

function ajaxcall() {

    alert('inside ajaxcall');   

    var xmlhttp;   
	if (window.XMLHttpRequest)   
	{  
		xmlhttp=new XMLHttpRequest(); 
	}   
	else if (window.ActiveXObject)   
	{   
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");   
	}   
	else  
	{   
		alert("Your browser does not support XMLHTTP!");   
	}   

	var URL = "http://localhost:8080/AjaxDemo/myexample.action?name=ramesh";

	xmlhttp.open("GET", URL, true);
	
	xmlhttp.onreadystatechange = function() {
		if(xmlhttp.readyState==4)   
		{   
			alert(xmlhttp.responseText);   
		}   
	};
	
	xmlhttp.send(null);
}

here is my action class:

public class MyExample implements ParameterAware, ServletResponseAware {

	private Map<String, String[]> param;
	
	public void setServletResponse(HttpServletResponse response) {

		response.setContentType("text/xml");
        response.setHeader("Cache-Control", "no-cache");
        
        try {
        	response.getWriter().write("hello");
        } catch(IOException e) {}
		
	}

	public void setParameters(Map<String, String[]> param) {
		this.param = param;
	}
	
    public String execute() throws Exception {

    	System.out.println("inside execute");
    	
    	if (param != null && param.get("name") != null) {

    		System.out.println("name is " + ((String [])param.get("name"))[0]);
    		
    	}

		return "success";
    }

	public String demo() {

    	System.out.println("inside demo");

		return "success";
    }
}

Thanks.

[Ankit Garg]

response.setContentType("text/xml");  
response.setHeader("Cache-Control", "no-cache");  

try {  
     response.getWriter().write("hello");  
} catch(IOException e) {}

You must be talking about this piece of code. When your action sends the request to a JSP page, this content will be ignored. If you don't want to send the request to the JSP, then return null from the execute method. You can't send response from action and JSP both...

[Ramesh Babu Essampalli]

thanks a lot ankit it works after returning null from action class.

[David Newton]

Why aren't you using a JavaScript library for the client side functionality?

Why are you using the parameter map when Struts 2 provides the means to avoid all those machinations?

[Ramesh Babu Essampalli]

david,

i am trying to create dynamic textfields on ajax function call. it was suggested in the link below:

http://www.coderanch.com/t/468632/Struts/null-pointer-exception-struts

but was facing problem in returning values into response. that is now solved after returning null from the action class.

but now, i have another issue related to it.

i have a list of textfields in the jsp shown below:

<s:iterator value="mylist" status="pos">
	<s:textfield name="name[%{#pos.index}]" ></s:textfield>
</s:iterator>

 

i have added mylist variable into my action class. and adding a value to mylist on ajaxcall. please refer my modified action class below:

public class MyExample implements ParameterAware, ServletResponseAware {

	private Map<String, String[]> param;
	
	private ArrayList<String> mylist;
	
	public ArrayList<String> getMylist() {
		return mylist;
	}

	public void setMylist(ArrayList<String> mylist) {
		this.mylist = mylist;
	}

	public void setServletResponse(HttpServletResponse response) {

		response.setContentType("text/xml");
        response.setHeader("Cache-Control", "no-cache");
        
        try {
        	response.getWriter().write("hello");
        } catch(IOException e) {}
		
	}

	public void setParameters(Map<String, String[]> param) {
		this.param = param;
	}
	
    public String execute() throws Exception {

    	System.out.println("inside execute");
    	
    	mylist = new ArrayList<String>();
    	mylist.add("ajit");
    	mylist.add("ramesh");
    	
    	if (param != null && param.get("name") != null) {
    		
    		mylist.add("ravi");

    		System.out.println("name is " + ((String [])param.get("name"))[0]);
    		return null;
    		
    	}

		return "success";
    }

	public String demo() {

    	System.out.println("inside demo");

		return "success";
    }
}

 

but the change in value of mylist is not adding a textfield into the jsp page. please give me some direction to add the textfield dynamically using ajax. thanks.