当前位置导航:炫浪网>>网络学院>>编程开发>>JAVA教程>>Java进阶

http断点续传简单实现


   /*
  **SiteFileFetch.java
  */
  package NetFox;
  import java.io.*;
  import java.net.*;
  
  
  public class SiteFileFetch extends Thread {
  
  
  SiteInfoBean siteInfoBean = null; //文件信息Bean
  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; //文件下载的临时信息
  DataOutputStream output; //输出到文件的输出流
  
  //负责整个文件的抓取,控制内部线程(FileSplitterFetch类)
  public SiteFileFetch(SiteInfoBean bean) throws IOException
  {
  siteInfoBean = bean;
  //tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath()));
  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();
  }
  // fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(),
  siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);
  // Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ",
  nEndPos = " + nFileLength);
  // fileSplitterFetch[nPos.length-1].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;
  
  
  //count++;
  //if(count>4)
  // siteStop();
  }
  
  
  System.err.println("文件下载结束!");
  }
  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 represent access is error
  }
  
  
  String sHeader;
  
  
  for(int i=1;;i++)
  {
  //DataInputStream in = new DataInputStream(httpConnection.getInputStream ());
  //Utility.log(in.readLine());
  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;
  }
  
  
  //保存下载信息(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);
  }
  
  
  //停止文件下载
  public void siteStop()
  {
  bStop = true;
  for(int i=0;i<nStartPos.length;i++)
  fileSplitterFetch[i].splitterStop();
  
  
  }
  }
  //负责部分文件的抓取
  **FileSplitterFetch.java
  */
  package NetFox;
  
  
  import java.io.*;
  import java.net.*;
  
  
  public class FileSplitterFetch extends Thread {
  
  
  String sURL; //File URL
  long nStartPos; //File Snippet Start Position
  long nEndPos; //File Snippet End Position
  int nThreadID; //Thread's ID
  boolean bDownOver = false; //Downing is over
  boolean bStop = false; //Stop identical
  FileAccessI fileAccessI = null; //File Access interface
  
  
  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;
  fileAccessI = new FileAccessI(sName,nStartPos);//定位
  }
  
  
  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();
  //logResponseHead(httpConnection);
  
  
  byte[] b = new byte[1024];
  int nRead;
  while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop)
  {
  nStartPos += fileAcces
相关内容
赞助商链接