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众所都知见于安全性考虑，applet在ie、netscape中没有写入文件的能力，包括本地、服务器文件。那么我们怎样才能实现一些数据的保留呢？（象本程序代码中记录积分的功能）。
一个方法是通过服务器端的servlet写入文件，applet端的代码如下：
private void Send(){
message=score+"#"+tf.getText ();
showStatus("Message send");
String queryString="/servlet/javaduke.servlet.SaveServlet?message="+
URLEncoder.encode(message);
p("Attempting to send:"+message);
try{
connect=(new URL(chatURL,queryString)).openConnection();
showStatus("打开连接");
showStatus(connect.toString ());
System.out.println("open connection");
connect.setDefaultUseCaches(false);
connect.setUseCaches (false);
connect.setDoInput (true);
connect.setDoOutput(false);
System.out.println("dooutput false");
connect.connect();
System.out.println("open stream");
p("Made connection to"+connect);
showStatus("试图连接、读取回应");
InputStreamReader reader=new InputStreamReader(connect.getInputStream ());
BufferedReader in=new BufferedReader(reader);
message=in.readLine ();
while(message!=null){
tf.setText(message);
message=in.readLine ();
}
showStatus("对话成功");
}
catch(MalformedURLException e2){
System.err.println ("MalformedURLException!");
e2.printStackTrace (System.err );
showStatus("MalformedURLException");
}
catch(IOException e1){
System.err.println ("IOException");
e1.printStackTrace (System.err);
showStatus(e1.toString ());
}
}
server端代码如下！
Servlet写入文件(www.mycgiserver.com调试成功）
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class SaveServlet extends HttpServlet {
String counter,counter2;
//Initialize global variables
public void init(ServletConfig config) throws ServletException {
super.init(config);
}
//Service the request
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
File file=new File("/members/YourID/servlet/gamelog.txt");
RandomAccessFile raf;
if(!file.exists()){
raf=new RandomAccessFile(file,"rw");
counter="210#javaduke ";
raf.seek(0);
raf.writeBytes(counter);
raf.close();
}
else{
counter=request.getParameter("message");
raf=new RandomAccessFile(file,"rw");
raf.seek(0);
raf.writeBytes(counter);
raf.close();
}
response.setContentType("text/html");
PrintWriter out = new PrintWriter (response.getOutputStream());
out.print("Saved OK!");
out.close();
}
//Get Servlet information
public String getServletInfo() {
return "game.SaveServlet Information";
}
}
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