filesplitterfetch.java

Java网络编程实例第2章实例.rar

package download;

import java.io.*;
import java.net.*;

/**
 * Title:        Java实现网络文件传输
 * Description:  在客户端请求Web服务器传输指定文件，并将文件保存。
 * Copyright:    Copyright (c) 2002
 * Company:
 * @author 钟华
 * @version 1.0
 */

public class FileSplitterFetch extends Thread {
  String sURL; // 定义文件传输时使用的变量
  long nStartPos; // 分段文件传输开始位置
  long nEndPos; // 分段文件传输结束位置
  int nThreadID; // 子线程ID
  boolean bDownOver = false; // 完成文件传输
  boolean bStop = false; // 停止文件传输
  FileAccess fileAccess = null;

  public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException{
    this.sURL = sURL;
    this.nStartPos = nStart;
    this.nEndPos = nEnd;
    nThreadID = id;
    fileAccess = new FileAccess(sName,nStartPos);
  }

  public void run(){
    while(nStartPos < nEndPos && !bStop){
      try{
        URL url = new URL(sURL);
        HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
        httpConnection.setRequestProperty("User-Agent","NetFox");
        String sProperty = "bytes="+nStartPos+"-";
        httpConnection.setRequestProperty("RANGE",sProperty);
        Utility.log(sProperty);
        InputStream input = httpConnection.getInputStream();
        byte[] b = new byte[1024];
        int nRead;
        while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop){
          nStartPos += fileAccess.write(b,0,nRead);
        }
        Utility.log("Thread " + nThreadID + " is over!");
        bDownOver = true;
      }
      catch(Exception e){
        e.printStackTrace ();
      }
    }
  }

  public void logResponseHead(HttpURLConnection con){
    for(int i=1;;i++){
      String header=con.getHeaderFieldKey(i);
      if(header!=null)
        Utility.log(header+" : "+con.getHeaderField(header));
      else
        break;
    }
  }

  public void splitterStop(){
    bStop = true;
  }
}