<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" isELIgnored="false" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="author" content="hoojo & [url=http://hoojo.cnblogs.com]http://hoojo.cnblogs.com[/url]"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <%@ include file="/tags/jquery-lib.jsp"%> <script type="text/javascript"> $(function () { window.setInterval(function () { $.get("${pageContext.request.contextPath}/communication/user/ajax.mvc", {"timed": new Date().getTime()}, function (data) { $("#logs").append("[data: " + data + " ]<br/>"); }); }, 3000); }); </script> </head> <body> <div id="logs"></div> </body> </html>
@RequestMapping("/ajax") public void ajax(long timed, HttpServletResponse response) throws Exception { PrintWriter writer = response.getWriter(); Random rand = new Random(); // 死循环 查询有无数据变化 while (true) { Thread.sleep(300); // 休眠300毫秒,模拟处理业务等 int i = rand.nextInt(100); // 产生一个0-100之间的随机数 if (i > 20 && i < 56) { // 如果随机数在20-56之间就视为有效数据,模拟数据发生变化 long responseTime = System.currentTimeMillis(); // 返回数据信息,请求时间、返回数据时间、耗时 writer.print("result: " + i + ", response time: " + responseTime + ", request time: " + timed + ", use time: " + (responseTime - timed)); break; // 跳出循环,返回数据 } else { // 模拟没有数据变化,将休眠 hold住连接 Thread.sleep(1300); } } }
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" isELIgnored="false" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <%@ include file="/tags/jquery-lib.jsp"%> <script type="text/javascript"> $(function () { window.setInterval(function () { $("#logs").append("[data: " + $($("#frame").get(0).contentDocument).find("body").text() + " ]<br/>"); $("#frame").attr("src", "${pageContext.request.contextPath}/communication/user/ajax.mvc?timed=" + new Date().getTime()); // 延迟1秒再重新请求 window.setTimeout(function () { window.frames["polling"].location.reload(); }, 1000); }, 5000); }); </script> </head> <body> <iframe id="frame" name="polling" style="display: none;"></iframe> <div id="logs"></div> </body> </html>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" isELIgnored="false" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="author" content="hoojo & [url=http://hoojo.cnblogs.com]http://hoojo.cnblogs.com[/url]"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <%@ include file="/tags/jquery-lib.jsp"%> <script type="text/javascript"> $(function () { window.setInterval(function () { var url = "${pageContext.request.contextPath}/communication/user/ajax.mvc?timed=" + new Date().getTime(); var $iframe = $('<iframe id="frame" name="polling" style="display: none;" src="' + url + '"></iframe>'); $("body").append($iframe); $iframe.load(function () { $("#logs").append("[data: " + $($iframe.get(0).contentDocument).find("body").text() + " ]<br/>"); $iframe.remove(); }); }, 5000); }); </script> </head> <body> <div id="logs"></div> </body> </html>
<script type="text/javascript"> $(function () { (function iframePolling() { var url = "${pageContext.request.contextPath}/communication/user/ajax.mvc?timed=" + new Date().getTime(); var $iframe = $('<iframe id="frame" name="polling" style="display: none;" src="' + url + '"></iframe>'); $("body").append($iframe); $iframe.load(function () { $("#logs").append("[data: " + $($iframe.get(0).contentDocument).find("body").text() + " ]<br/>"); $iframe.remove(); // 递归 iframePolling(); }); })(); }); </script>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" isELIgnored="false" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <%@ include file="/tags/jquery-lib.jsp"%> <script type="text/javascript"> $(function () { (function longPolling() { $.ajax({ url: "${pageContext.request.contextPath}/communication/user/ajax.mvc", data: {"timed": new Date().getTime()}, dataType: "text", timeout: 5000, error: function (XMLHttpRequest, textStatus, errorThrown) { $("#state").append("[state: " + textStatus + ", error: " + errorThrown + " ]<br/>"); if (textStatus == "timeout") { // 请求超时 longPolling(); // 递归调用 // 其他错误,如网络错误等 } else { longPolling(); } }, success: function (data, textStatus) { $("#state").append("[state: " + textStatus + ", data: { " + data + "} ]<br/>"); if (textStatus == "success") { // 请求成功 longPolling(); } } }); })(); }); </script> </head> <body>
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引用:shaunlan 发表于 2018-11-15 10:13 收获很大,公司现在的webIM就是采用long-polling方式
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