断点下载

很多时候我们需要在Android设备上下载远程服务器上的文件进安装，前两天晚上我看到一个视频，写了两个晚上，大概理解一下。直接通过Android提供的Http类访问远程服务器，这里AndroidHttpClient是SDK 2.2中新出的方法，
下载断点文件。
下面让我们看一下图先。
                    让我们看一下代码的实现方法。
            packagecom.smart.db;
            importjava.util.HashMap;
            importjava.util.Map;
            importandroid.content.Context;
            importandroid.database.Cursor;
            importandroid.database.sqlite.SQLiteDatabase;
            /**
            *业务bean
            *
            */
            publicclassFileService{
            privateDBOpenHelperopenHelper;
            publicFileService(Contextcontext){
            openHelper=newDBOpenHelper(context);
            }
            /**
            *获取每条线程已经下载的文件长度
            *@parampath
            *@return
            */
            publicMap<Integer,Integer>getData(Stringpath){
            SQLiteDatabasedb=openHelper.getReadableDatabase();
            Cursorcursor=db.rawQuery("selectthreadid,downlengthfromSmartFileDownlogwheredownpath=?",newString[]{path});
            Map<Integer,Integer>data=newHashMap<Integer,Integer>();
            while(cursor.moveToNext()){
            data.put(cursor.getInt(0),cursor.getInt(1));
            }
            cursor.close();
            db.close();
            returndata;
            }
            /**
            *保存每条线程已经下载的文件长度
            *@parampath
            *@parammap
            */
            publicvoidsave(Stringpath,Map<Integer,Integer>map){//intthreadid,intposition
            SQLiteDatabasedb=openHelper.getWritableDatabase();
            db.beginTransaction();
            try{
            for(Map.Entry<Integer,Integer>entry:map.entrySet()){
            db.execSQL("insertintoSmartFileDownlog(downpath,threadid,downlength)values(?,?,?)",
            newObject[]{path,entry.getKey(),entry.getValue()});
            }
            db.setTransactionSuccessful();
            }finally{
            db.endTransaction();
            }
            db.close();
            }
            /**
            *实时更新每条线程已经下载的文件长度
            *@parampath
            *@parammap
            */
            publicvoidupdate(Stringpath,Map<Integer,Integer>map){
            SQLiteDatabasedb=openHelper.getWritableDatabase();
            db.beginTransaction();
            try{
            for(Map.Entry<Integer,Integer>entry:map.entrySet()){
            db.execSQL("updateSmartFileDownlogsetdownlength=?wheredownpath=?andthreadid=?",
            newObject[]{entry.getValue(),path,entry.getKey()});
            }
            db.setTransactionSuccessful();
            }finally{
            db.endTransaction();
            }
            db.close();
            }
            /**
            *当文件下载完成后，删除对应的下载记录
            *@parampath
            */
            publicvoiddelete(Stringpath){
            SQLiteDatabasedb=openHelper.getWritableDatabase();
            db.execSQL("deletefromSmartFileDownlogwheredownpath=?",newObject[]{path});
            db.close();
            }
            
            }
            
            
            packagecom.smart.impl;
            importjava.io.File;
            importjava.io.RandomAccessFile;
            importjava.net.HttpURLConnection;
            importjava.net.URL;
            importjava.util.LinkedHashMap;
            importjava.util.Map;
            importjava.util.UUID;
            importjava.util.concurrent.ConcurrentHashMap;
            importjava.util.regex.Matcher;
            importjava.util.regex.Pattern;
            importandroid.content.Context;
            importandroid.util.Log;
            importcom.smart.db.FileService;
            /**
            *文件下载器
            *@author[email protected]
            */
            publicclassSmartFileDownloader{
            privatestaticfinalStringTAG="SmartFileDownloader";
            privateContextcontext;
            privateFileServicefileService;
            /*已下载文件长度*/
            privateintdownloadSize=0;
            /*原始文件长度*/
            privateintfileSize=0;
            /*线程数*/
            privateSmartDownloadThread[]threads;
            /*本地保存文件*/
            privateFilesaveFile;
            /*缓存各线程下载的长度*/
            privateMap<Integer,Integer>data=newConcurrentHashMap<Integer,Integer>();
            /*每条线程下载的长度*/
            privateintblock;
            /*下载路径*/
            privateStringdownloadUrl;
            /**
            *获取线程数
            */
            publicintgetThreadSize(){
            returnthreads.length;
            }
            /**
            *获取文件大小
            *@return
            */
            publicintgetFileSize(){
            returnfileSize;
            }
            /**
            *累计已下载大小
            *@paramsize
            */
            protectedsynchronizedvoidappend(intsize){
            downloadSize+=size;
            }
            /**
            *更新指定线程最后下载的位置
            *@paramthreadId线程id
            *@parampos最后下载的位置
            */
            protectedvoidupdate(intthreadId,intpos){
            this.data.put(threadId,pos);
            }
            /**
            *保存记录文件
            */
            protectedsynchronizedvoidsaveLogFile(){
            this.fileService.update(this.downloadUrl,this.data);
            }
            /**
            *构建文件下载器
            *@paramdownloadUrl下载路径
            *@paramfileSaveDir文件保存目录
            *@paramthreadNum下载线程数
            */
            publicSmartFileDownloader(Contextcontext,StringdownloadUrl,FilefileSaveDir,intthreadNum){
            try{
            this.context=context;
            this.downloadUrl=downloadUrl;
            fileService=newFileService(this.context);
            URLurl=newURL(this.downloadUrl);
            if(!fileSaveDir.exists())fileSaveDir.mkdirs();
            this.threads=newSmartDownloadThread[threadNum];
            HttpURLConnectionconn=(HttpURLConnection)url.openConnection();
            conn.setConnectTimeout(5*1000);
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept","image/gif,image/jpeg,image/pjpeg,image/pjpeg,application/x-shockwave-flash,application/xaml+xml,application/vnd.ms-xpsdocument,application/x-ms-xbap,application/x-ms-application,application/vnd.ms-excel,application/vnd.ms-powerpoint,application/msword,*/*");
            conn.setRequestProperty("Accept-Language","zh-CN");
            conn.setRequestProperty("Referer",downloadUrl);
            conn.setRequestProperty("Charset","UTF-8");
            conn.setRequestProperty("User-Agent","Mozilla/4.0(compatible;MSIE8.0;WindowsNT5.2;Trident/4.0;.NETCLR1.1.4322;.NETCLR2.0.50727;.NETCLR3.0.04506.30;.NETCLR3.0.4506.2152;.NETCLR3.5.30729)");
            conn.setRequestProperty("Connection","Keep-Alive");
            conn.connect();
            printResponseHeader(conn);
            if(conn.getResponseCode()==200){
            this.fileSize=conn.getContentLength();//根据响应获取文件大小
            if(this.fileSize<=0)thrownewRuntimeException("Unkownfilesize");
            
            Stringfilename=getFileName(conn);
            this.saveFile=newFile(fileSaveDir,filename);/*保存文件*/
            Map<Integer,Integer>logdata=fileService.getData(downloadUrl);
            if(logdata.size()>0){
            for(Map.Entry<Integer,Integer>entry:logdata.entrySet())
            data.put(entry.getKey(),entry.getValue());
            }
            this.block=(this.fileSize%this.threads.length)==0?this.fileSize/this.threads.length:this.fileSize/this.threads.length+1;
            if(this.data.size()==this.threads.length){
            for(inti=0;i<this.threads.length;i++){
            this.downloadSize+=this.data.get(i+1);
            }
            print("已经下载的长度"+this.downloadSize);
            }
            }else{
            thrownewRuntimeException("servernoresponse");
            }
            }catch(Exceptione){
            print(e.toString());
            thrownewRuntimeException("don'tconnectionthisurl");
            }
            }
            /**
            *获取文件名
            */
            privateStringgetFileName(HttpURLConnectionconn){
            Stringfilename=this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/')+1);
            if(filename==null||"".equals(filename.trim())){//如果获取不到文件名称
            for(inti=0;;i++){
            Stringmine=conn.getHeaderField(i);
            if(mine==null)break;
            if("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())){
            Matcherm=Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase());
            if(m.find())returnm.group(1);
            }
            }
            filename=UUID.randomUUID()+".tmp";//默认取一个文件名
            }
            returnfilename;
            }
            
            /**
            *开始下载文件
            *@paramlistener监听下载数量的变化,如果不需要了解实时下载的数量,可以设置为null
            *@return已下载文件大小
            *@throwsException
            */
            publicintdownload(SmartDownloadProgressListenerlistener)throwsException{
            try{
            RandomAccessFilerandOut=newRandomAccessFile(this.saveFile,"rw");
            if(this.fileSize>0)randOut.setLength(this.fileSize);
            randOut.close();
            URLurl=newURL(this.downloadUrl);
            if(this.data.size()!=this.threads.length){
            this.data.clear();//清除数据
            for(inti=0;i<this.threads.length;i++){
            this.data.put(i+1,0);
            }
            }
            for(inti=0;i<this.threads.length;i++){
            intdownLength=this.data.get(i+1);
            if(downLength<this.block&&this.downloadSize<this.fileSize){//该线程未完成下载时,继续下载
            this.threads=newSmartDownloadThread(this,url,this.saveFile,this.block,this.data.get(i+1),i+1);
            this.threads.setPriority(7);
            this.threads.start();
            }else{
            this.threads=null;
            }
            }
            this.fileService.save(this.downloadUrl,this.data);
            booleannotFinish=true;//下载未完成
            while(notFinish){//循环判断是否下载完毕
            Thread.sleep(900);
            notFinish=false;//假定下载完成
            for(inti=0;i<this.threads.length;i++){
            if(this.threads!=null&&!this.threads.isFinish()){
            notFinish=true;//下载没有完成
            if(this.threads.getDownLength()==-1){//如果下载失败,再重新下载
            this.threads=newSmartDownloadThread(this,url,this.saveFile,this.block,this.data.get(i+1),i+1);
            this.threads.setPriority(7);
            this.threads.start();
            }
            }
            }
            if(listener!=null)listener.onDownloadSize(this.downloadSize);
            }
            fileService.delete(this.downloadUrl);
            }catch(Exceptione){
            print(e.toString());
            thrownewException("filedownloadfail");
            }
            returnthis.downloadSize;
            }
            /**
            *获取Http响应头字段
            *@paramhttp
            *@return
            */
            publicstaticMap<String,String>getHttpResponseHeader(HttpURLConnectionhttp){
            Map<String,String>header=newLinkedHashMap<String,String>();
            for(inti=0;;i++){
            Stringmine=http.getHeaderField(i);
            if(mine==null)break;
            header.put(http.getHeaderFieldKey(i),mine);
            }
            returnheader;
            }
            /**
            *打印Http头字段
            *@paramhttp
            */
            publicstaticvoidprintResponseHeader(HttpURLConnectionhttp){
            Map<String,String>header=getHttpResponseHeader(http);
            for(Map.Entry<String,String>entry:header.entrySet()){
            Stringkey=entry.getKey()!=null?entry.getKey()+":":"";
            print(key+entry.getValue());
            }
            }
            //打印日志
            privatestaticvoidprint(Stringmsg){
            Log.i(TAG,msg);
            }
            
            
            }
            packagecom.smart.impl;
            importjava.io.File;
            importjava.io.InputStream;
            importjava.io.RandomAccessFile;
            importjava.net.HttpURLConnection;
            importjava.net.URL;
            importandroid.util.Log;
            publicclassSmartDownloadThreadextendsThread{
            privatestaticfinalStringTAG="SmartDownloadThread";
            privateFilesaveFile;
            privateURLdownUrl;
            privateintblock;
            /**下载开始位置*/
            privateintthreadId=-1;
            privateintdownLength;
            privatebooleanfinish=false;
            privateSmartFileDownloaderdownloader;
            publicSmartDownloadThread(SmartFileDownloaderdownloader,URLdownUrl,FilesaveFile,intblock,intdownLength,intthreadId){
            this.downUrl=downUrl;
            this.saveFile=saveFile;
            this.block=block;
            this.downloader=downloader;
            this.threadId=threadId;
            this.downLength=downLength;
            }
            
            @Override
            publicvoidrun(){
            if(downLength<block){//未下载完成
            try{
            HttpURLConnectionhttp=(HttpURLConnection)downUrl.openConnection();
            http.setConnectTimeout(5*1000);
            http.setRequestMethod("GET");
            http.setRequestProperty("Accept","image/gif,image/jpeg,image/pjpeg,image/pjpeg,application/x-shockwave-flash,application/xaml+xml,application/vnd.ms-xpsdocument,application/x-ms-xbap,application/x-ms-application,application/vnd.ms-excel,application/vnd.ms-powerpoint,application/msword,*/*");
            http.setRequestProperty("Accept-Language","zh-CN");
            http.setRequestProperty("Referer",downUrl.toString());
            http.setRequestProperty("Charset","UTF-8");
            intstartPos=block*(threadId-1)+downLength;//开始位置
            intendPos=block*threadId-1;//结束位置
            http.setRequestProperty("Range","bytes="+startPos+"-"+endPos);//设置获取实体数据的范围
            http.setRequestProperty("User-Agent","Mozilla/4.0(compatible;MSIE8.0;WindowsNT5.2;Trident/4.0;.NETCLR1.1.4322;.NETCLR2.0.50727;.NETCLR3.0.04506.30;.NETCLR3.0.4506.2152;.NETCLR3.5.30729)");
            http.setRequestProperty("Connection","Keep-Alive");
            
            InputStreaminStream=http.getInputStream();
            byte[]buffer=newbyte[1024];
            intoffset=0;
            print("Thread"+this.threadId+"startdownloadfromposition"+startPos);
            RandomAccessFilethreadfile=newRandomAccessFile(this.saveFile,"rwd");
            threadfile.seek(startPos);
            while((offset=inStream.read(buffer,0,1024))!=-1){
            threadfile.write(buffer,0,offset);
            downLength+=offset;
            downloader.update(this.threadId,downLength);
            downloader.saveLogFile();
            downloader.append(offset);
            }
            threadfile.close();
            inStream.close();
            print("Thread"+this.threadId+"downloadfinish");
            this.finish=true;
            }catch(Exceptione){
            this.downLength=-1;
            print("Thread"+this.threadId+":"+e);
            }
            }
            }
            privatestaticvoidprint(Stringmsg){
            Log.i(TAG,msg);
            }
            /**
            *下载是否完成
            *@return
            */
            publicbooleanisFinish(){
            returnfinish;
            }
            /**
            *已经下载的内容大小
            *@return如果返回值为-1,代表下载失败
            */
            publiclonggetDownLength(){
            returndownLength;
            }
            }
            packagecom.smart.activoty.download;
            importjava.io.File;
            importandroid.app.Activity;
            importandroid.os.Bundle;
            importandroid.os.Environment;
            importandroid.os.Handler;
            importandroid.os.Message;
            importandroid.view.View;
            importandroid.widget.Button;
            importandroid.widget.EditText;
            importandroid.widget.ProgressBar;
            importandroid.widget.TextView;
            importandroid.widget.Toast;
            importcom.smart.impl.SmartDownloadProgressListener;
            importcom.smart.impl.SmartFileDownloader;
            publicclassSmartDownloadActivityextendsActivity{
            privateProgressBardownloadbar;
            privateEditTextpathText;
            privateTextViewresultView;
            privateHandlerhandler=newHandler(){
            @Override//信息
            publicvoidhandleMessage(Messagemsg){
            switch(msg.what){
            case1:
            intsize=msg.getData().getInt("size");
            downloadbar.setProgress(size);
            floatresult=(float)downloadbar.getProgress()/(float)downloadbar.getMax();
            intp=(int)(result*100);
            resultView.setText(p+"%");
            if(downloadbar.getProgress()==downloadbar.getMax())
            Toast.makeText(SmartDownloadActivity.this,R.string.success,1).show();
            break;
            case-1:
            Toast.makeText(SmartDownloadActivity.this,R.string.error,1).show();
            break;
            }
            
            }
            };
            
            @Override
            publicvoidonCreate(BundlesavedInstanceState){
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            
            Buttonbutton=(Button)this.findViewById(R.id.button);
            downloadbar=(ProgressBar)this.findViewById(R.id.downloadbar);
            pathText=(EditText)this.findViewById(R.id.path);
            resultView=(TextView)this.findViewById(R.id.result);
            button.setOnClickListener(newView.OnClickListener(){
            @Override
            publicvoidonClick(Viewv){
            Stringpath=pathText.getText().toString();
            if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
            Filedir=Environment.getExternalStorageDirectory();//文件保存目录
            download(path,dir);
            }else{
            Toast.makeText(SmartDownloadActivity.this,R.string.sdcarderror,1).show();
            }
            }
            });
            }
            //对于UI控件的更新只能由主线程(UI线程)负责，如果在非UI线程更新UI控件，更新的结果不会反映在屏幕上，某些控件还会出错
            privatevoiddownload(finalStringpath,finalFiledir){
            newThread(newRunnable(){
            @Override
            publicvoidrun(){
            try{
            SmartFileDownloaderloader=newSmartFileDownloader(SmartDownloadActivity.this,path,dir,3);
            intlength=loader.getFileSize();//获取文件的长度
            downloadbar.setMax(length);
            loader.download(newSmartDownloadProgressListener(){
            @Override
            publicvoidonDownloadSize(intsize){//可以实时得到文件下载的长度
            Messagemsg=newMessage();
            msg.what=1;
            msg.getData().putInt("size",size);
            handler.sendMessage(msg);
            }});
            }catch(Exceptione){
            Messagemsg=newMessage();//信息提示
            msg.what=-1;
            msg.getData().putString("error","下载失败");//如果下载错误，显示提示失败！
            handler.sendMessage(msg);
            }
            }
            }).start();//开始
            
            }
            }
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