在Struts2的操作类Ajax响应 [英] Ajax response in struts2 action class

问题描述

我想实现Ajax在JSP中使用的Struts2（避免表单提交）。我用AJAX code通过URL来传递请求Struts2的行动。但是从struts2的响应是不是获取填充在JAP。它显示空值。我的code。使用AJAX是如下调用行动的jsp。

I am trying to implement ajax in jsp(avoid form submit) using struts2. I used ajax code to pass request via url to struts2 action. But the response from struts2 is not get populated in jap. Its showing "null" value. My code to call a action in jsp using AJAX is as Follows.

    function ajaxEditFunctionCall(){  
 var xmlHttp;
     var url = "ajaxcall.action?stateName="+frm.stateName.value;  
  try{   
    xmlHttp=new XMLHttpRequest();   
  }catch (e){
      try{ 
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); 
      }catch (e){ 
          try{  
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); 
            }catch (e){
                alert("Your browser does not support AJAX!");
                return false;
            }
      }
  }
  alert(1);
  xmlHttp.onreadystatechange = showMessage; 
      alert(2);

  xmlHttp.open("GET", URL, true); 

       alert(3);
       xmlHttp.send(null);  
  }

      function showMessage() { 
       alert("Inside Show Message1");
         alert(xmlhttp.readyState);
             if(xmlhttp.readyState==4)  
            { 
             alert("Inside Show Message2&ReadyState4");
                 alert(xmlhttp.responseText);  
            }  
       }  

   Included following code in Action Class:

public String ajaxcall() throws Exception{

     System.out.println("Inside AjaxCall");
     String errorXml = "This is a Sample to Check";  

     response.setContentType("text/html"); 
     response.setHeader("Cache-Control", "no-cache"); 
         response.setContentType("text/html");   
     response.getWriter().write(errorXml); 

     return null;

}

code包含在struts.xml中：

Code included in Struts.xml:

  <action name="ajaxcall" class="com.logic.action.CustomerAction" method="ajaxcall">
       <result name="success" >/pages/customer/addCustomer.jsp</result> 
   </action>

我认为错误是在动作类响应语句并在struts.xml中。任何一个可以请帮我解决这个问题。在此先感谢。

I think the error is in the action class-response statement and in struts.xml. Can any one please help me to fix this issue. Thanks in Advance.

推荐答案

下面，校正需要做的JavaScript函数。当你说 VAR XMLHTTP ，它有一个范围，在函数内部 ajaxEditFunctionCall 而不是为 showMessage 。此外， XMLHTTP 在 showMessage（）不一样的 XMLHTTP 在 ajaxEditFunctionCall 。因此，保持 VAR XMLHTTP 宣布全球和进行更正。这里是工作code：

Here, the correction needs to be done to the JavaScript function. When you say var xmlHttp, it has a scope inside the function ajaxEditFunctionCall and not for the showMessage. Also, xmlhttp in showMessage() is not same as xmlHttp object in ajaxEditFunctionCall. So, keep the var xmlHttp declaration global and make the corrections. Here is the working code:

<script type="text/javascript">
            var xmlHttp;
            function ajaxEditFunctionCall(){

                var URL = "ajaxcall.action?stateName=State1";
                try{
                    xmlHttp=new XMLHttpRequest();
                }catch (e){
                    try{
                        xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
                    }catch (e){
                        try{
                            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
                        }catch (e){
                            alert("Your browser does not support AJAX!");
                            return false;
                        }
                    }
                }
                //alert(1);
                xmlHttp.onreadystatechange = showMessage;
                //alert(2);

                xmlHttp.open("GET", URL, true);

                //alert(3);
                xmlHttp.send(null);
            }

            function showMessage() {
                //alert("Inside Show Message1");
                //alert(xmlHttp.readyState);
                if(xmlHttp.readyState==4)
                {
                    alert("Inside Show Message2&ReadyState4");
                    alert(xmlHttp.responseText);
                }
            }  
        </script>

Java的code是：

The Java code is:

public class CustomerAction extends ActionSupport implements ServletResponseAware {

    HttpServletResponse response;

    public String ajaxcall() {

        System.out.println("Inside AjaxCall");
        String errorXml = "This is a Sample to Check";

        response.setContentType("text/html");
        response.setHeader("Cache-Control", "no-cache");
        try {
            response.getWriter().write(errorXml);
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }

        return null;
    }

    public void setServletResponse(HttpServletResponse response) {
        this.response = response;
    }
}

在struts.xml中是：

The struts.xml is:

<struts>
    <constant name="struts.devMode" value="true" />
    <package name="default" extends="struts-default">
        <action name="ajaxcall" class="com.logic.action.CustomerAction" method="ajaxcall">
            <result name="success" >/pages/customer/addCustomer.jsp</result>
        </action>
    </package>
</struts>

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