发布一篇HTTP多线程断点续传下载的实验 - 仓酷云

1.importjava.io.BufferedInputStream;
2.importjava.io.BufferedWriter;
3.importjava.io.File;
4.importjava.io.OutputStreamWriter;
5.importjava.io.RandomAccessFile;
6.importjava.net.Socket;
7.importjava.net.URL;
8.importjava.net.URLConnection;
9.importjava.util.HashMap;
10.importjava.util.Map;
11.
12./**
13.*HTTP的多线程下载工具。
14.*
15.*@author赵学庆www.java2000.net
16.*/
17.publicclassHTTPDownloaderextendsThread{
18.//要下载的页面
19.privateStringpage;
20.
21.//保留的路径
22.privateStringsavePath;
23.
24.//线程数
25.privateintthreadNumber=2;
26.
27.//来历地点
28.privateStringreferer;
29.
30.privateStringcookie;
31.
32.intthreadPointer=0;
33.
34.privateMap<Integer,HTTPDownloaderThread>threadPool=newHashMap<Integer,HTTPDownloaderThread>();//线程迟
35.
36.//最小的块尺寸。假如文件尺寸除以线程数小于这个，则会削减线程数。37.privateintMIN_BLOCK=10*1024;
38.
39.publicstaticvoidmain(String[]args)throwsException{
40.HTTPDownloaderd=newHTTPDownloader("http://www.xxxxx.com/a.rar",null,"d://a.rar",10,null);
41.d.down();
42.}
43.
44.publicvoidrun(){
45.try{
46.down();
47.}catch(Exceptione){
48.e.printStackTrace();
49.}
50.}
51.
52./**
53.*下载操纵
54.*
55.*@throwsException
56.*/
57.publicvoiddown()throwsException{
58.URLurl=newURL(page);//创立URL
59.URLConnectioncon=url.openConnection();//创建毗连
60.con.setRequestProperty("Referer",referer==null?page:referer);
61.con.setRequestProperty("UserAgent","Mozilla/4.0(compatible;MSIE6.0;WindowsNT5.1;flashget)");
62.intcontentLen=con.getContentLength();//取得资本长度
63.if((contentLen/MIN_BLOCK+1)<threadNumber){
64.threadNumber=contentLen/MIN_BLOCK+1;//调剂下载线程数65.}
66.if(threadNumber>10){
67.threadNumber=10;
68.}
69.intbegin=0;
70.intstep=contentLen/threadNumber+1;
71.intend=0;
72.HTTPDownloaderThreadthread;
73.for(threadPointer=0;threadPointer<threadNumber;threadPointer++){
74.end+=step;
75.if(end>contentLen){
76.end=contentLen;
77.}
78.thread=newHTTPDownloaderThread(this,threadPointer,begin,end);
79.threadPool.put(threadPointer,thread);
80.thread.start();
81.begin=end;
82.}
83.}
84.
85./**
86.*一个线程完活了。
87.*
88.*@paramid完活的线程id
89.*/
90.publicsynchronizedvoidfinished(intid){
91.threadNumber--;
92.threadPool.remove(id);
93.if(threadNumber<=0){
94.System.out.println("FINISHED:"+savePath);
95.Filef1=newFile(savePath+".tmp");
96.Filef2=newFile(savePath);
97.//假如方针文件已存在，则实验删除它
98.//最多实验3次，距离1秒钟。
99.inttimes=3;
100.while(f2.exists()&&times>0){
101.if(f2.delete()){
102.break;
103.}
104.try{
105.Thread.sleep(1000);
106.}catch(InterruptedExceptione){
107.e.printStackTrace();
108.}
109.times--;
110.}
111.if(!f2.exists()){
112.if(!f1.renameTo(f2)){
113.System.out.println("更名失利!");
114.}
115.}else{
116.System.out.println("方针文件存在，且没法删除,没法更名");
117.}
118.}else{
119.intsize=0;
120.HTTPDownloaderThreado=null;
121.//实验查找一个能够分管的线程
122.for(HTTPDownloaderThreadthread:threadPool.values()){
123.if(thread.endPos-thread.curPos>size){
124.size=thread.endPos-thread.curPos;
125.o=thread;
126.}
127.}
128.if(size>MIN_BLOCK*2){
129.if(o.isAlive()){
130.intendPos=o.endPos;
131.intbeginPos=o.endPos-((o.endPos-o.curPos)/2);
132.o.endPos=beginPos;
133.threadNumber++;
134.threadPointer++;
135.HTTPDownloaderThreadthread=newHTTPDownloaderThread(this,threadPointer,beginPos,endPos);
136.threadPool.put(threadPointer,thread);
137.System.out.println("AHelpThreadfor"+o.id+"isstartedwith:"+threadPointer);
138.thread.start();
139.}
140.}
141.}
142.}
143.
144.publicHTTPDownloader(){
145.}
146.
147./**
148.*下载
149.*
150.*@parampage被下载的页面
151.*@paramsavePath保留的路径
152.*/
153.publicHTTPDownloader(Stringpage,StringsavePath){
154.this(page,savePath,10);
155.}
156.
157./**
158.*下载
159.*
160.*@parampage被下载的页面
161.*@paramsavePath保留的路径
162.*@paramthreadNumber线程数
163.*/
164.publicHTTPDownloader(Stringpage,StringsavePath,intthreadNumber){
165.this(page,page,savePath,10,null);
166.}
167.
168./**
169.*下载
170.*
171.*@parampage被下载的页面
172.*@paramsavePath保留的路径
173.*@paramthreadNumber线程数
174.*@paramreferer来历
175.*/
176.publicHTTPDownloader(Stringpage,Stringreferer,StringsavePath,intthreadNumber,Stringcookie){
177.this.page=page;
178.this.savePath=savePath;
179.this.threadNumber=threadNumber;
180.this.referer=referer;
181.}
182.
183.publicStringgetPage(){
184.returnpage;
185.}
186.
187.publicvoidsetPage(Stringpage){
188.this.page=page;
189.}
190.
191.publicStringgetSavePath(){
192.returnsavePath;
193.}
194.
195.publicvoidsetSavePath(StringsavePath){
196.this.savePath=savePath;
197.}
198.
199.publicintgetThreadNumber(){
200.returnthreadNumber;
201.}
202.
203.publicvoidsetThreadNumber(intthreadNumber){
204.this.threadNumber=threadNumber;
205.}
206.
207.publicStringgetReferer(){
208.returnreferer;
209.}
210.
211.publicvoidsetReferer(Stringreferer){
212.this.referer=referer;
213.}
214.
215.publicStringgetCookie(){
216.returncookie;
217.}
218.
219.publicvoidsetCookie(Stringcookie){
220.this.cookie=cookie;
221.}
222.}
223.
224./**
225.*下载线程
226.*
227.*@author赵学庆www.java2000.net
228.*/
229.classHTTPDownloaderThreadextendsThread{
230.HTTPDownloadermanager;
231.
232.intstartPos;
233.
234.intendPos;
235.
236.intid;
237.
238.intcurPos;
239.
240.intBUFFER_SIZE=40960;
241.
242.intreadByte=0;
243.
244.HTTPDownloaderThread(HTTPDownloadermanager,intid,intstartPos,intendPos){
245.this.id=id;
246.this.manager=manager;
247.this.startPos=startPos;
248.this.endPos=endPos;
249.}
250.
251.publicvoidrun(){
252.System.out.println("线程"+id+"启动,"+startPos+"-"+endPos);
253.//创立一个buff
254.BufferedInputStreambis=null;
255.RandomAccessFilefos=null;
256.//缓冲区巨细
257.byte[]buf=newbyte[BUFFER_SIZE];
258.booleantimeout=false;
259.Socketsocket=null;
260.try{
261.curPos=startPos;
262.Filefile=newFile(manager.getSavePath()+".tmp");
263.//创立RandomAccessFile
264.fos=newRandomAccessFile(file,"rw");
265.//从startPos入手下手
266.fos.seek(startPos);
267.intindex=manager.getPage().indexOf("/",8);
268.Stringhost=manager.getPage().substring(7,index);
269.//System.out.println(host);
270.socket=newSocket(host,80);
271.socket.setSoTimeout(30000);
272.//写进数据
273.BufferedWriterwr=newBufferedWriter(newOutputStreamWriter(socket.getOutputStream(),"UTF-8"));
274.StringBuilderb=newStringBuilder();
275.b.append("GET"+manager.getPage().substring(index)+"HTTP/1.1
");
276.b.append("Host:"+host+"
");
277.b.append("Referer:"+(manager.getReferer()==null?manager.getPage():manager.getReferer())+"
");
278.b.append("UserAgent:Mozilla/4.0(compatible;MSIE6.0;WindowsNT5.1;flashget;
");
279.b.append("Range:bytes="+startPos+"-"+endPos+"
");
280.b.append("
");
281.//System.out.println(b.toString());
282.wr.write(b.toString());
283.wr.flush();
284.//上面一段向依据文件写进数据,curPos为以后写进的未知,这里会判别是不是小于endPos,
285.//假如凌驾endPos就代表该线程已实行终了
286.bis=newBufferedInputStream(socket.getInputStream());
287.//读取直到换行
288.intch;
289.booleanfoundBR=false;
290.while(true){
291.ch=bis.read();
292.if(ch==0xD){
293.ch=bis.read();
294.if(ch==0xA){
295.if(foundBR){
296.break;
297.}
298.foundBR=true;
299.}else{
300.foundBR=false;
301.}
302.}else{
303.foundBR=false;
304.}
305.}
306.intlen=-1;
307.while(curPos<endPos){
308.//System.out.println(id+"="+(endPos-curPos));
309.len=bis.read(buf,0,BUFFER_SIZE);
310.if(len==-1){
311.break;
312.}
313.fos.write(buf,0,len);
314.//System.out.println(id+"=WriteOK!");
315.curPos=curPos+len;
316.if(curPos>endPos){
317.//猎取准确读取的字节数
318.readByte+=len-(curPos-endPos)+1;
319.}else{
320.readByte+=len;
321.}
322.}
323.System.out.println("线程"+id+"已下载终了:"+readByte);
324.}catch(Exceptionex){
325.timeout=true;
326.}finally{
327.if(bis!=null){
328.try{
329.bis.close();
330.}catch(Exceptione){
331.System.out.println("封闭文件失利(1)!");
332.}
333.}
334.if(fos!=null){
335.try{
336.fos.close();
337.}catch(Exceptione){
338.System.out.println("封闭文件失利(2)!");
339.}
340.}
341.if(socket!=null){
342.try{
343.socket.close();
344.}catch(Exceptione){
345.System.out.println("封闭链接失利!");
346.}
347.}
348.}
349.if(timeout){
350.System.out.println(id+"timeout,restart...");
351.newHTTPDownloaderThread(manager,id,curPos,endPos).start();
352.}else{
353.manager.finished(id);
354.}
355.}
356.}

复制代码