關于applet寫入文件的處理

2019-11-18 15:06:03

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　　關于applet寫入文件的處理

眾所都知見于安全性考慮，applet在ie、netscape中沒有寫入文件的能力，包括本地、服務器文件。那么我們怎樣才能實現一些數據的保留呢？（象本程序代碼中記錄積分的功能）。

一個方法是通過服務器端的servlet寫入文件，applet端的代碼如下：

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("打開連接");
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("試圖連接、讀取回應");
InputStreamReader reader=new InputStreamReader(connect.getInputStream ());
BufferedReader in=new BufferedReader(reader);
message=in.readLine ();
while(message!=null){
tf.setText(message);
message=in.readLine ();
}
showStatus("對話成功");
}
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端代碼如下！
Servlet寫入文件(www.mycgiserver.com調試成功）

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");
Random accessFile 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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