Issue
It is a very basic request-response test. Browser sends "hello from browser" to servlet using jQuery $.ajax API, and servlet receives this message, then create a JSON object using org.json.simple library and sends back to browser a JSON response with message "hello from server".
I am running this on localhost and just assume my IP address is 123.123.12.123, the platform is Ubuntu, server is Tomcat 6.0, running in the Eclipse IDE.
Test 1. I start the server from Eclipse, open Firefox, enter http://localhost:8080/myproject/test.jsp, I can see servlet receives message and browser receives response, test passed.
Test 2. server is still running at the Eclipse at Ubuntu, I start Windows 7 guest machine from VirtualBox and the Firefox browser in the Windows 7, enter http://123.123.12.123:8080/myproject/test.jsp, works as I expected, test passed.
Test 3. server is still running at Eclipse at Ubuntu, open Internet Explorer 9 browser, give it address http://123.123.12.123:8080/myproject/test.jsp, nothing happens. The debug gives me
Response HTTP/1.1 200 OK
Response body {"message":"hello from server"}
The test.jsp is
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.js" type="text/javascript"></script>
<script type="text/javascript" src="release/js/libs/json2.js"></script>
<script>
$(document).ready(function(){
var request = ({"message":'Hello from browser'});
var jsonobj=JSON.stringify(request);
$.ajax({
data: {para:jsonobj},
dataType: 'json',
url: './TestServlet',
type: 'POST',
success: function(jsonObj){
alert(jsonObj.message);
},
error: function() {
alert('Ajax readyState: '+xhr.readyState+'\nstatus: '+xhr.status + ' ' + err);
}
});
});
</script>
<body>
</body>
</html>
The servlet code is
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
/**
* Servlet implementation class TestServlet
*/
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TestServlet() {
super();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf8");
response.setCharacterEncoding("utf8");
response.setContentType("application/json");
PrintWriter out = response.getWriter();
JSONObject jsonObj = (JSONObject) JSONValue.parse(request.getParameter("para"));
System.out.println(jsonObj.get("message"));
JSONObject obj = new JSONObject();
obj.put("message", "hello from server");
out.print(obj);
}
}
Update:
After a closer look by change
error: function() {
alert('Ajax readyState: '+xhr.readyState+'\nstatus: '+xhr.status + ' ' + err);
}
to
error: function(xhr,err) {
alert('Ajax readyState: '+xhr.readyState+'\nstatus: '+xhr.status + ' ' + err);
}
I got alert readyState:0 and status:0. But I can see {"message":"hello from server"} at Response body and the response header is
Key Value Response HTTP/1.1 200 OK
Solution
IE caches AJAX requests aggressively (more than Firefox, Chrome, and Safari, anyway).
Sometimes you need to set cache header controller when request. Like cache:false. I tried to fix your code like this
request.setCharacterEncoding("utf8");
//response.setCharacterEncoding("utf8");
response.setContentType("application/json");
PrintWriter out = response.getWriter();
JSONObject jsonObj = (JSONObject) JSONValue.parse(request.getParameter("para"));
System.out.println(jsonObj.get("message"));
JSONObject obj = new JSONObject();
obj.put("message", "hello from server");
out.print(obj.toString());
I changed your response content-type from application/json; charset=utf8 to just application/json and that worked.
Answered By - viyancs
Answer Checked By - Mildred Charles (JavaFixing Admin)
