http断点续传简单实现（java)

inparis

/***SiteFileFetch.java*/package NetFox;import java.io.*;import java.net.*; public class SiteFileFetch extends Thread { SiteInfoBean siteInfoBean = null; //文件信息Beanlong[] 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;}}elsebreak;}}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 URLlong nStartPos; //File Snippet Start Positionlong nEndPos; //File Snippet End Positionint nThreadID; //Thread´s IDboolean bDownOver = false; //Downing is overboolean bStop = false; //Stop identicalFileAccessI 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));elsebreak;}} 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 URLprivate String sFilePath; //Saved File´s Pathprivate String sFileName; //Saved File´s Nameprivate int nSplitter; //Count of Splited Downloading File public SiteInfoBean(){//nSplitter的缺省值为5//default value of nSplitter is 5this("","","",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.exetry{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();}}