fileuploadthread.java

一个用APPLET写的文件上传系统

package wjhk.jupload;

import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;

  /*
  * Known Bugs: System out of memory Exception.
  * Solution  : Nothing!
  * Tryed but didn't work:
  *             - Flush the OutputStream once it has outputed 1MB.
  *             - Call System.gc() once it has outputed 1MB.
  *             - Sleep for 1 Second so that System GC gets a chance to run.
  * Work Around: Breakup the file into smaller ones then upload =)
  */
public class FileUploadThread extends Thread {

  //------------- INFORMATION --------------------------------------------
  public static final double VERSION = 1.0;
  public static final String AUTHOR = "William Kwong Jinhua";
  public static final String AUTHOR_EMAIL = "[e-mail]";
  public static final String DESCRIPTION = "Java Thread to upload files into a web server.";
  public static final String LAST_MODIFIED = "01 July 2002";

  //------------- STATUS OF THREAD ---------------------------------------
  // Files asked to be uploaded into the server.
  private File[] aTotalFiles;
  private String uploadURL;

  // Progress Bar.
  private JProgressBar progress;
  private long totalFilesLength;
  private long uploadedLength;

  // Server Output.
  private StringBuffer sb = new StringBuffer();
  private void addServerOutPut(String s){
    if(0 < sb.length() || !s.equals("")){
      sb.append(s);
    }
  }
  public StringBuffer getServerOutput(){
    return sb;
  }

  private Exception e = null;
  public Exception getException(){
    return e;
  }

  public void setProgressPanel(JProgressBar pgrBar){
    progress = pgrBar;
  }

  private boolean stop = false;
  public void stopUpload(){
    this.stop = true;
  }

  //------------- CONSTRUCTOR --------------------------------------------

  public FileUploadThread(File[] files, String uploadURL){
    aTotalFiles = files;
    this.uploadURL = uploadURL;
    totalFilesLength = 0;
    for(int i=0; i < aTotalFiles.length; i++){
      totalFilesLength += aTotalFiles[i].length();
    }
  }

  //------------- CLEAN UP -----------------------------------------------
  public void close(){
    aTotalFiles = null;

    e = null;

    sb = null;

  }

  //------------- THE HEART OF THE PROGRAME ------------------------------

  public void run() {
    URL url = null;
    URLConnection urlConn = null;
    DataOutputStream dOut = null;
    BufferedReader bInp = null;
    try{
      url = new URL(uploadURL);
      // Setting up the connection for upload.
      urlConn = url.openConnection();
      urlConn.setDoInput (true);
      urlConn.setDoOutput (true);
      urlConn.setUseCaches (false);
      String boundary = "-----------------------------" + getRandomString();
      urlConn.setRequestProperty("Content-Type",
                                 "multipart/form-data; boundary=" +
                                 boundary.substring(2, boundary.length()));
      String CRLF = "\r\n";

      // Retrieve OutputStream For upload (Post).
      dOut = new DataOutputStream(urlConn.getOutputStream());

      // Actual Uploading part.
      StringBuffer sb;
      File f;
      uploadedLength = 0;
      progress.setMaximum((int)totalFilesLength);
      for(int i=0; i < aTotalFiles.length && !stop; i++){
        f = aTotalFiles[i];
        sb = new StringBuffer();
        // Line 1.
        sb.append(boundary);sb.append(CRLF);
        // Line 2.
        sb.append("Content-Disposition: form-data; name=\"File");sb.append(i);
        sb.append("\"; filename=\"");sb.append(f.toString());
        sb.append("\"");sb.append(CRLF);
        // Line 3 & Empty Line 4.
        sb.append("Content-Type: application/octet-stream");
        sb.append(CRLF);sb.append(CRLF);
        // Write to Server the 4 Lines, a File and the CRLF.
        dOut.writeBytes(sb.toString());
        uploadFileStream(f,dOut);
        dOut.writeBytes(CRLF);
      }
      // Telling the Server we have Finished.
      dOut.writeBytes(boundary);dOut.writeBytes("--");dOut.writeBytes(CRLF);
      dOut.flush ();
      if(!stop) progress.setString("File(s) uploaded. Wait for server response!");

      // Reading input from Server.
      // NOTE: You have to call getInputStream AFTER you have posted all
      // your files. Anything you try to write to the server after calling the
      // getInputStream will be lost.
      // PROBLEM: You will only find out the status of the server (server/page
      // is reachable/exists) after getInputStream. It would be very bad if
      // we spend all our time writing to it then find out it was down or
      // page doesn't exist!
      // -- Server Down --
      // java.net.SocketException: Connection reset by peer: JVM_recv in socket input stream read
      // java.net.SocketException: Unexpected end of file from server.
      // -- Post page not found --
      // java.io.FileNotFoundException: <<URL>>
      bInp = new BufferedReader(new InputStreamReader(urlConn.getInputStream ()));

      String str;
      while (null != ((str = bInp.readLine()))){
        this.addServerOutPut(str);
      }
    }catch(Exception e){
      this.e = e;
    }finally{
      try{
        bInp.close();
      }catch(Exception e){}
      bInp = null;
      try{
        dOut.close();
      }catch(Exception e){}
      dOut = null;
      urlConn = null;
      url = null;
    }
  }

  private String getRandomString(){
    String alphaNum="1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    StringBuffer sbRan = new StringBuffer(11);
    int num;
    for(int i = 0; i < 11; i++){
      num = (int)(Math.random()* (alphaNum.length() - 1));
      sbRan.append(alphaNum.substring(num, num+1));
    }
    return sbRan.toString();
  }

  private void uploadFileStream(File f, DataOutputStream dOut)
                                throws FileNotFoundException,
                                IOException{
    byte[] byteBuff = null;
    FileInputStream fis = null;
    try{
      int numBytes = 0;
      byteBuff = new byte[1024];
      fis = new FileInputStream(f);
      while(-1 != (numBytes = fis.read(byteBuff)) && !stop){
        dOut.write(byteBuff, 0, numBytes);
        uploadedLength += numBytes;
        if(null != progress) progress.setValue((int)uploadedLength);
      }
    }finally{
      try{
        fis.close();
      }catch(Exception e){}
      byteBuff = null;
    }
  }
}