sitefilefetch.java

java网络编程 包含全书所有代码编程以及实例

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 SiteFileFetch extends Thread {   // 传输文件线程类
  SiteInfoBean siteInfoBean = null; //文件信息Bean
  long[] nPos;
  long[] nStartPos; //开始位置
  long[] nEndPos; //结束位置
  FileSplitterFetch[] fileSplitterFetch; //子线程对象
  long nFileLength; //文件长度
  boolean bFirst = true; //是否第一次取文件
  boolean bStop = false; //停止标志
  File tmpFile; //文件传输临时信息
  DataOutputStream output; //输出到文件的输出流

  public SiteFileFetch(SiteInfoBean bean) throws IOException{
    siteInfoBean = bean;
    tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info");
    if(tmpFile.exists ()){
      bFirst = false;
      read_nPos();
    }
    else{
      nStartPos = new long[bean.getNSplitter()];
      nEndPos = new long[bean.getNSplitter()];
    }
  }

  public void run(){
    //获得文件长度
    //分割文件
    //实例FileSplitterFetch
    //启动FileSplitterFetch线程
    //等待子线程返回
    try{
      if(bFirst){
        nFileLength = getFileSize();
        if(nFileLength == -1){
          System.err.println("File Length is not known!");
        }
        else
          if(nFileLength == -2){
            System.err.println("File is not access!");
          }
          else{
            for(int i=0;i<nStartPos.length;i++){
              nStartPos[i] = (long)(i*(nFileLength/nStartPos.length));
            }
            for(int i=0;i<nEndPos.length-1;i++){
              nEndPos[i] = nStartPos[i+1];
            }
            nEndPos[nEndPos.length-1] = nFileLength;
          }
      }
      //启动子线程
      fileSplitterFetch = new FileSplitterFetch[nStartPos.length];
      for(int i=0;i<nStartPos.length;i++){
        fileSplitterFetch[i] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),
        siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),
        nStartPos[i],nEndPos[i],i);
        Utility.log("Thread " + i + " , nStartPos = " + nStartPos[i] + ", nEndPos = " + nEndPos[i]);
        fileSplitterFetch[i].start();
      }
      //等待子线程结束
      //int count = 0;
      //是否结束while循环
      boolean breakWhile = false;
      while(!bStop){
        write_nPos();
        Utility.sleep(500);
        breakWhile = true;
        for(int i=0;i<nStartPos.length;i++){
          if(!fileSplitterFetch[i].bDownOver){
          breakWhile = false;
          break;
        }
      }
      if(breakWhile)
        break;
      }
      System.out.println("文件传输结束！");
    }
    catch(Exception e){
      e.printStackTrace ();
    }
  }

  //获得文件长度
  public long getFileSize(){
    int nFileLength = -1;
    try{
      URL url = new URL(siteInfoBean.getSSiteURL());
      HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
      httpConnection.setRequestProperty("User-Agent","NetFox");
      int responseCode=httpConnection.getResponseCode();
      if(responseCode>=400){
        processErrorCode(responseCode);
        return -2; //-2 为Web服务器响应错误
      }
      String sHeader;
      for(int i=1;;i++){
        sHeader=httpConnection.getHeaderFieldKey(i);
        if(sHeader!=null){
          if(sHeader.equals("Content-Length")){
            nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader));
            break;
          }
        }
        else
          break;
      }
    }
    catch(IOException e){e.printStackTrace ();}
    catch(Exception e){e.printStackTrace ();}
    Utility.log(nFileLength);
    return nFileLength;
  }

  //保存传输信息（文件指针位置）
  private void write_nPos(){
    try{
      output = new DataOutputStream(new FileOutputStream(tmpFile));
      output.writeInt(nStartPos.length);
      for(int i=0;i<nStartPos.length;i++){
        // output.writeLong(nPos[i]);
        output.writeLong(fileSplitterFetch[i].nStartPos);
        output.writeLong(fileSplitterFetch[i].nEndPos);
      }
      output.close();
    }
    catch(IOException e){e.printStackTrace ();}
    catch(Exception e){e.printStackTrace ();}
  }

  //读取保存的下载信息（文件指针位置）
  private void read_nPos(){
    try{
      DataInputStream input = new DataInputStream(new FileInputStream(tmpFile));
      int nCount = input.readInt();
      nStartPos = new long[nCount];
      nEndPos = new long[nCount];
      for(int i=0;i<nStartPos.length;i++){
        nStartPos[i] = input.readLong();
        nEndPos[i] = input.readLong();
      }
      input.close();
    }
    catch(IOException e){e.printStackTrace ();}
    catch(Exception e){e.printStackTrace ();}
  }

  private void processErrorCode(int nErrorCode){
    System.err.println("Error Code : " + nErrorCode);
  }

  //停止文件传输
  public void siteStop(){
    bStop = true;
    for(int i=0;i<nStartPos.length;i++)
      fileSplitterFetch[i].splitterStop();
  }
}