当客户访问网站时就去读这个文件，将服务器重新启动前的计数读入，并在此基础上增加1，然后将新的计数写入到文件中。
参考代码如下：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<%!
int number = 0;
File file = new File("count.txt");
synchronized void countPeople()
{
if(!file.exists())
{
number++;
try{
file.createNewFile();
FileOutputStream out = new FileOutputStream("count.txt");
DataOutputStream dataOut = new DataOutputStream(out);
dataOut.writeInt(number);
dataOut.close();
}catch(IOException ex){}
}
else
try{
FileInputStream in = new FileInputStream("count.txt");
DataInputStream dataIn = new DataInputStream(in);
number = dataIn.readInt();
number++;
in.close();
dataIn.close();
FileOutputStream out = new FileOutputStream("count.txt");
DataOutputStream dataOut = new DataOutputStream(out);
dataOut.writeInt(number);
out.close();
dataOut.close();
}catch(IOException ex){}
}
%>
<%
countPeople();
%>
<p>
您是第
<%=number %>
个访问网站的客户。
</p>
</body>
</html>
