一个可以防止刷新的JSP计数器_JSP教程-查字典教程网

<%@ page contentType="text/html;charset=gb2312" %>

<%-- 以前学ASP时,用ASP做防止刷新的计数器很简单,以下是一个用JSP做的计数器--%>

<html>

<head>

<title>jsp计数器</title>

</head>

<body>

<%@ page import="java.io.*" %>

//out.println(request.getHeader("Cookie"));

String currentRecord = null;//保存文本的变量

BufferedReader file; //BufferedReader对象，用于读取文件数据

String nameOfTextFile = "count.txt";

//读取

file = new BufferedReader(new FileReader(nameOfTextFile));

String readStr =null;

int writeStr =0; //如果计数文本中的计数值为空则让它显示时变成1并写入

try

{ readStr = file.readLine(); }

catch (IOException e)

{ System.out.println("读取数据错误."); }

if (readStr == null) readStr = "没有任何记录";

//判断cookie,第一次登陆时加1,刷新时不累计计数

else if (request.getHeader("Cookie")==null)

{ writeStr = Integer.parseInt(readStr)+1;}

else

{ writeStr = Integer.parseInt(readStr);}

//写入时控制因为刷新引起的重复计数

if (request.getHeader("Cookie")==null)

{

try {

PrintWriter pw = new PrintWriter(new FileOutputStream(nameOfTextFile));

pw.println(writeStr);

pw.close();}

catch(IOException e) {

out.println(e.getMessage());}

}

您是CNJSP的第<%=writeStr%>位客人。

</body>

</html>