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JSONP跨域獲取JSON數據

JSONP跨域獲取JSON數據

客戶端請求數據

<!doctype html>
<html>
<head>
<title>App Engine Demo</title>
<script
	src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
</head>
<body>
	<div id="result">Loading...</div>
	<br />
	<p>add p</p>
	<br />
	<script>
		$(document).ready(function() {
			$.ajax({
				async : false,
				url : "https://hanotfun.appspot.com/demo",
				type : "GET",
				dataType : 'jsonp',
				jsonp : 'callback',
				success : function(data) {
					$('#result').html("Hello, " + data.name);
				}
			});
		});
	</script>
</body>
</html>

服務器端必須對處理請求，不能直接返回json數據，而要用callback參數對數據進行包裝

/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package myapp;

import java.io.IOException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DemoServlet extends HttpServlet {
  @Override
  public void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws IOException {
	  String callback = req.getParameter("callback");
		if (callback != null && callback.length() > 0) {
			resp.setContentType("text/plain");
			resp.getWriter().println(callback + "({ \"name\": \"World\" })");
		} else {
			resp.setContentType("text/plain");
			resp.getWriter().println("{ \"name\": \"World\" }");
		}
  }
}
//如果不包裝會報“Uncaught SyntaxError: Unexpected token :”錯誤

檢測到請求中包含callback參數時對返回數據進行包裝，否則直接返回json數據。

reference

Updated: 2020-12-20 11:17
Created: 2017-03-19 01:33