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http断点续传简单实现(java)

摘要: http断点续传简单实现(java)

/* **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 //启动子线程 fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; for(int i=0;i //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 //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 //停止文件下载 public void siteStop() { bStop = true; for(int i=0;i } } //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 += fileAccessI.write(b,0,nRead); //if(nThreadID == 1) // Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); }
Utility.log("Thread " + nThreadID + " is over!"); bDownOver = true; //nPos = fileAccessI.write (b,0,nRead); } catch(Exception e){e.printStackTrace ();} } }
//打印回应的头信息 public void logResponseHead(HttpURLConnection con) { for(int i=1;;i++) { String header=con.getHeaderFieldKey(i); if(header!=null) //responseHeaders.put(header,httpConnection.getHeaderField(header)); Utility.log(header+" : "+con.getHeaderField(header)); else break; } }
public void splitterStop() { bStop = true; }
}
/* **FileAccess.java *//文件访问(定位,写) package NetFox; import java.io.*;
public class FileAccessI implements Serializable{
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 RandomAccessFile oSavedFile; long nPos;
public FileAccessI() throws IOException { this("",0); }
public FileAccessI(String sName,long nPos) throws IOException { oSavedFile = new RandomAccessFile(sName,"rw"); this.nPos = nPos; oSavedFile.seek(nPos); }
public synchronized int write(byte[] b,int nStart,int nLen) { int n = -1; try{ oSavedFile.write(b,nStart,nLen); n = nLen; } catch(IOException e) { e.printStackTrace (); }
return n; } }
/* **SiteInfoBean.java */ package NetFox;
public class SiteInfoBean {
private String sSiteURL; //Site's URL private String sFilePath; //Saved File's Path private String sFileName; //Saved File's Name private int nSplitter; //Count of Splited Downloading File
public SiteInfoBean() {//nSplitter的缺省值为5 //default value of nSplitter is 5 this("","","",5); }
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) { sSiteURL= sURL; sFilePath = sPath; sFileName = sName; this.nSplitter = nSpiltter;
}
public String getSSiteURL() { return sSiteURL; }
public void setSSiteURL(String value) { sSiteURL = value; }
public String getSFilePath() { return sFilePath; }
public void setSFilePath(String value) { sFilePath = value; }
public String getSFileName() { return sFileName; }
public void setSFileName(String value) { sFileName = value; }
public int getNSplitter() { return nSplitter; }
public void setNSplitter(int nCount) { nSplitter = nCount; } }
/* **Utility.java */ package NetFox;
public class Utility {
public Utility() {
}
//线程睡眠 public static void sleep(int nSecond) { try{ Thread.sleep(nSecond); } catch(Exception e) { e.printStackTrace (); } }
//日志 public static void log(String sMsg) { System.err.println(sMsg); }
public static void log(int sMsg) { System.err.println(sMsg); } }
/* **TestMethod.java */ package NetFox;
public class TestMethod {
public TestMethod() { ///xx/weblogic60b2_win.exe try{ SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); //SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); SiteFileFetch fileFetch = new SiteFileFetch(bean); fileFetch.start(); } catch(Exception e){e.printStackTrace ();}
}
public static void main(String[] args) { new TestMethod(); } }
对该文的评论 suntsang(2002-9-6 9:15:19)
trace
cxj_2000(2002-9-6 8:35:48)
我写过用socket实现的http断点下载的程序,其实写起来不难,关键是你要看懂蚂蚁里面的日志和RFC中的http协议
shybt(2002-9-5 16:13:41)
可以成功运行,java学习者下载学习了
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