java网络编程-Ajax+servlet实例
Ajax异步请求,servlet产生随机数据,Html页面无刷新显示。 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 java.util.Random; public class ajaxServlet extends HttpServlet{ private static final String CONTENT_TYPE="text/xml; charset=gb2312"; public void init() throws ServletException{} public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{ response.setContentType(CONTENT_TYPE); response.setHeader("Cache-Control","no-cache"); response.setHeader("Pragma","no-cache"); response.setDateHeader("Expires",0); PrintWriter out=response.getWriter(); String action=request.getParameter("action");if(("send").equals(action)){ Random random = new Random(); String AA=Integer.toString(Math.abs(random.nextInt())); String BB=Integer.toString(Math.abs(random.nextInt())); String CC=Integer.toString(Math.abs(random.nextInt())); String DD=Integer.toString(Math.abs(random.nextInt())); StringBuffer sb=new StringBuffer(); sb.append(AA); sb.append("@@@"); sb.append(BB); sb.append("@@@"); sb.append(CC); sb.append("@@@"); sb.append(DD); out.write(sb.toString()); out.close(); } }} |
二、testajax.html function getResult(){
var url = "/Tajax/AajaxServlet?action=send";
if (window.XMLHttpRequest) {
req = new XMLHttpRequest();
}else if (window.ActiveXObject){
req = new ActiveXObject("Microsoft.XMLHTTP");
}
if(req){
req.open("GET",url, true);
req.onreadystatechange = complete;
req.send(null);
}
}
/*分析返回的文本文档*/
function complete(){
if (req.readyState == 4) {
if (req.status == 200) {
// alert(req.responseText);
var strResult = unescape(req.responseText);
var arrResult = strResult.split("@@@");
RemoveRow(); //删除以前的数据.
num1 = arrResult[0]; //字段num1的值
num2 = arrResult[1]; //字段num2的值
num3 = arrResult[2];
num4 = arrResult[3];
row1= tb.insertRow();
cell1 = row1.insertCell();
cell1.innerText = num1;
cell2 = row1.insertCell();
cell2.innerText = num2;
row2= tb.insertRow();
cell3 = row2.insertCell();
cell3.innerText = num3;
cell4 = row2.insertCell();
cell4.innerText = num4;
} else {
alert("There was a problem with the request.");
}
}
}
function RemoveRow(){//保留第一行表头,其余数据均删除.
var iRows = tb.rows.length;
for(var i=0;i< iRows-1;i++){
tb.deleteRow(1);
}
}
function MyShow(){//2秒自动刷新一次,2秒取得一次数据.
timer = window.setInterval("getResult()",2000);
}
</script> <body onload="MyShow()"> <form> </body> 三、web.xml <?xml version="1.0" encoding="ISO-8859-1"?> <web-app xmlns="http://java.sun.com/xml/ns/j2ee" <display-name>Welcome to Tomcat</display-name> <servlet>
运行图:
源代码网供稿. | |

