文件断点续传和下载

首先是文件上传，这个要用到服务器

关键代码：

 FileServer.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.io.RandomAccessFile;
import java.net.ServerSocket;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import util.FileLogInfo;
import util.StreamTool;



public class FileServer {
     private ExecutorService executorService;//线程池
     private int port;//监听端口
     private boolean quit = false;//退出
     private ServerSocket server;
     private Map<Long, FileLogInfo> datas = new HashMap<Long, FileLogInfo>();//存放断点数据,以后改为数据库存放
     public FileServer(int port)
     {
         this.port = port;
         //创建线程池，池中具有(cpu个数*50)条线程
         executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 50);
     }

    /**
      * 退出
      */
     public void quit()
     {
        this.quit = true;
        try
        {
            server.close();
        }catch (IOException e)
        {
            e.printStackTrace();
        }
     }

     /**
      * 启动服务
      * @throws Exception
      */
     public void start() throws Exception
     {
         server = new ServerSocket(port);//实现端口监听
         while(!quit)
         {
             try
             {
               Socket socket = server.accept();
               executorService.execute(new SocketTask(socket));//为支持多用户并发访问，采用线程池管理每一个用户的连接请求
             }catch (Exception e)
             {
                 e.printStackTrace();
             }
         }
     }

     private final class SocketTask implements Runnable
     {
        private Socket socket = null;
        public SocketTask(Socket socket)
        {
            this.socket = socket;
        }
        @Override
        public void run()
        {
            try
            {
                System.out.println("FileServer accepted connection "+ socket.getInetAddress()+ ":"+ socket.getPort());
                //得到客户端发来的第一行协议数据：Content-Length=143253434;filename=xxx.3gp;sourceid=
                //如果用户初次上传文件，sourceid的值为空。
                InputStream inStream = socket.getInputStream();
                String head = StreamTool.readLine(inStream);
                System.out.println("FileServer head:"+head);
                if(head!=null)
                {
                    //下面从协议数据中提取各项参数值
                    String[] items = head.split(";");
                    String filelength = items[0].substring(items[0].indexOf("=")+1);
                    String filename = items[1].substring(items[1].indexOf("=")+1);
                    String sourceid = items[2].substring(items[2].indexOf("=")+1);
                    //生成资源id，如果需要唯一性，可以采用UUID
                    long id = System.currentTimeMillis();
                    FileLogInfo log = null;
                    if(sourceid!=null && !"".equals(sourceid))
                    {
                        id = Long.valueOf(sourceid);
                        //查找上传的文件是否存在上传记录
                        log = find(id);
                    }
                    File file = null;
                    int position = 0;
                    //如果上传的文件不存在上传记录,为文件添加跟踪记录
                    if(log==null)
                    {
                        //设置存放的位置与当前应用的位置有关
                        File dir = new File("c:/temp/");
                        if(!dir.exists()) dir.mkdirs();
                        file = new File(dir, filename);
                        //如果上传的文件发生重名，然后进行改名
                        if(file.exists())
                        {
                            filename = filename.substring(0, filename.indexOf(".")-1)+ dir.listFiles().length+ filename.substring(filename.indexOf("."));
                            file = new File(dir, filename);
                        }
                        save(id, file);
                    }
                    // 如果上传的文件存在上传记录,读取上次的断点位置
                    else
                    {
                        System.out.println("FileServer have exits log not null");
                        //从上传记录中得到文件的路径
                        file = new File(log.getPath());
                        if(file.exists())
                        {
                            File logFile = new File(file.getParentFile(), file.getName()+".log");
                            if(logFile.exists())
                            {
                                Properties properties = new Properties();
                                properties.load(new FileInputStream(logFile));
                                //读取断点位置
                                position = Integer.valueOf(properties.getProperty("length"));
                            }
                        }
                    }
                    //***************************上面是对协议头的处理，下面正式接收数据***************************************
                    //向客户端请求传输数据
                    OutputStream outStream = socket.getOutputStream();
                    String response = "sourceid="+ id+ ";position="+ position+ "%";
                    //服务器收到客户端的请求信息后，给客户端返回响应信息：sourceid=1274773833264;position=position
                    //sourceid由服务生成，唯一标识上传的文件，position指示客户端从文件的什么位置开始上传
                    outStream.write(response.getBytes());
                    RandomAccessFile fileOutStream = new RandomAccessFile(file, "rwd");
                    //设置文件长度
                    if(position==0) fileOutStream.setLength(Integer.valueOf(filelength));
                    //移动文件指定的位置开始写入数据
                    fileOutStream.seek(position);
                    byte[] buffer = new byte[1024];
                    int len = -1;
                    int length = position;
                    //从输入流中读取数据写入到文件中，并将已经传入的文件长度写入配置文件，实时记录文件的最后保存位置
                    while( (len=inStream.read(buffer)) != -1)
                    {
                        fileOutStream.write(buffer, 0, len);
                        length += len;
                        Properties properties = new Properties();
                        properties.put("length", String.valueOf(length));
                        FileOutputStream logFile = new FileOutputStream(new File(file.getParentFile(), file.getName()+".log"));
                        //实时记录文件的最后保存位置
                        properties.store(logFile, null);
                        logFile.close();
                    }
                    //如果长传长度等于实际长度则表示长传成功
                    if(length==fileOutStream.length()){
                        delete(id);
                    }
                    fileOutStream.close();
                    inStream.close();
                    outStream.close();
                    file = null;
                }
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            finally{
                try
                {
                    if(socket!=null && !socket.isClosed()) socket.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
     }

     /**
      * 查找在记录中是否有sourceid的文件
      * @param sourceid
      * @return
      */
     public FileLogInfo find(Long sourceid)
     {
         return datas.get(sourceid);
     }

     /**
      * 保存上传记录，日后可以改成通过数据库存放
      * @param id
      * @param saveFile
      */
     public void save(Long id, File saveFile)
     {
         System.out.println("save logfile "+id);
         datas.put(id, new FileLogInfo(id, saveFile.getAbsolutePath()));
     }

     /**
      * 当文件上传完毕，删除记录
      * @param sourceid
      */
     public void delete(long sourceid)
     {
         System.out.println("delete logfile "+sourceid);
         if(datas.containsKey(sourceid)) datas.remove(sourceid);
     }

}

 由于在上面的流程图中已经进行了详细的分析，我在这儿就不讲了，只是在存储数据的时候服务器没有用数据库去存储，这儿只是为了方便，所以要想测试断点上传，服务器是不能停的，否则数据就没有了，在以后改进的时候应该用数据库去存储数据。

文件上传客户端：

关键代码：

UploadActivity.java

package com.hao;

import java.io.File;
import java.util.List;

import com.hao.upload.UploadThread;
import com.hao.upload.UploadThread.UploadProgressListener;
import com.hao.util.ConstantValues;
import com.hao.util.FileBrowserActivity;

import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
/**
 *
 * @author Administrator
 *
 */
public class UploadActivity extends Activity implements OnClickListener{
    private static final String TAG = "SiteFileFetchActivity";
    private Button download, upload, select_file;
    private TextView info;
    private static final int PROGRESS_DIALOG = 0;
    private ProgressDialog progressDialog;
    private UploadThread uploadThread;
    private String uploadFilePath = null;
    private String fileName;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.upload);
        initView();
    }

    private void initView(){
        download = (Button) findViewById(R.id.download);
        download.setOnClickListener(this);
        upload = (Button) findViewById(R.id.upload);
        upload.setOnClickListener(this);
        info = (TextView) findViewById(R.id.info);
        select_file = (Button) findViewById(R.id.select_file);
        select_file.setOnClickListener(this);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
                  if (requestCode == 1) {
                           Uri uri = data.getData();    // 接收用户所选文件的路径
                           info.setText("select: " + uri); // 在界面上显示路径
                           uploadFilePath = uri.getPath();
                           int last = uploadFilePath.lastIndexOf("/");
                           uploadFilePath = uri.getPath().substring(0, last+1);
                           fileName = uri.getLastPathSegment();
                  }
        }
    }

    protected Dialog onCreateDialog(int id) {
        switch(id) {
        case PROGRESS_DIALOG:
            progressDialog = new ProgressDialog(UploadActivity.this);
            progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            progressDialog.setButton("暂停", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // TODO Auto-generated method stub
                    uploadThread.closeLink();
                    dialog.dismiss();
                }
            });
            progressDialog.setMessage("正在上传...");
            progressDialog.setMax(100);
            return progressDialog;
        default:
            return null;
        }
    }

    /**
     * 使用Handler给创建他的线程发送消息，
     * 匿名内部类
     */
    private Handler handler = new Handler()
    {
        @Override
        public void handleMessage(Message msg)
        {
            //获得上传长度的进度
            int length = msg.getData().getInt("size");
            progressDialog.setProgress(length);
            if(progressDialog.getProgress()==progressDialog.getMax())//上传成功
            {
                progressDialog.dismiss();
                Toast.makeText(UploadActivity.this, getResources().getString(R.string.upload_over), 1).show();
            }
        }
    };

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        Resources r = getResources();
        switch(v.getId()){
            case R.id.select_file:
                Intent intent = new Intent();
                //设置起始目录和查找的类型
                intent.setDataAndType(Uri.fromFile(new File("/sdcard")), "*/*");//"*/*"表示所有类型，设置起始文件夹和文件类型
                intent.setClass(UploadActivity.this, FileBrowserActivity.class);
                startActivityForResult(intent, 1);
                break;
            case R.id.download:
                startActivity(new Intent(UploadActivity.this, SmartDownloadActivity.class));
                break;
            case R.id.upload:
                if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))//判断SDCard是否存在
                {
                    if(uploadFilePath == null){
                        Toast.makeText(UploadActivity.this, "还没设置上传文件", 1).show();
                    }
                    System.out.println("uploadFilePath:"+uploadFilePath+" "+fileName);
                    //取得SDCard的目录
                    File uploadFile = new File(new File(uploadFilePath), fileName);
                    Log.i(TAG, "filePath:"+uploadFile.toString());
                    if(uploadFile.exists())
                    {
                        showDialog(PROGRESS_DIALOG);
                        info.setText(uploadFile+" "+ConstantValues.HOST+":"+ConstantValues.PORT);
                        progressDialog.setMax((int) uploadFile.length());//设置长传文件的最大刻度
                        uploadThread = new UploadThread(UploadActivity.this, uploadFile, ConstantValues.HOST, ConstantValues.PORT);
                        uploadThread.setListener(new UploadProgressListener() {

                            @Override
                            public void onUploadSize(int size) {
                                // TODO Auto-generated method stub
                                Message msg = new Message();
                                msg.getData().putInt("size", size);
                                handler.sendMessage(msg);
                            }
                        });
                        uploadThread.start();
                    }
                    else
                    {
                        Toast.makeText(UploadActivity.this, "文件不存在", 1).show();
                    }
                }
                else
                {
                    Toast.makeText(UploadActivity.this, "SDCard不存在！", 1).show();
                }
                break;
        }

    }


}

 UploadThread.java

package com.hao.upload;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.net.Socket;

import android.content.Context;
import android.util.Log;

import com.hao.db.UploadLogService;
import com.hao.util.StreamTool;

public class UploadThread extends Thread {

    private static final String TAG = "UploadThread";
    /*需要上传文件的路径*/
    private File uploadFile;
    /*上传文件服务器的IP地址*/
    private String dstName;
    /*上传服务器端口号*/
    private int dstPort;
    /*上传socket链接*/
    private Socket socket;
    /*存储上传的数据库*/
    private UploadLogService logService;
    private UploadProgressListener listener;
    public UploadThread(Context context, File uploadFile, final String dstName,final int dstPort){
        this.uploadFile = uploadFile;
        this.dstName = dstName;
        this.dstPort = dstPort;
        logService = new UploadLogService(context);
    }

    public void setListener(UploadProgressListener listener) {
        this.listener = listener;
    }

    /**
     * 模拟断开连接
     */
    public void closeLink(){
        try{
            if(socket != null) socket.close();
        }catch(IOException e){
            e.printStackTrace();
            Log.e(TAG, "close socket fail");
        }
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        try {
            // 判断文件是否已有上传记录
            String souceid = logService.getBindId(uploadFile);
            // 构造拼接协议
            String head = "Content-Length=" + uploadFile.length()
                    + ";filename=" + uploadFile.getName() + ";sourceid="
                    + (souceid == null ? "" : souceid) + "%";
            // 通过Socket取得输出流
            socket = new Socket(dstName, dstPort);
            OutputStream outStream = socket.getOutputStream();
            outStream.write(head.getBytes());
            Log.i(TAG, "write to outStream");

            InputStream inStream = socket.getInputStream();
            // 获取到字符流的id与位置
            String response = StreamTool.readLine(inStream);
            Log.i(TAG, "response:" + response);
            String[] items = response.split(";");
            String responseid = items[0].substring(items[0].indexOf("=") + 1);
            String position = items[1].substring(items[1].indexOf("=") + 1);
            // 代表原来没有上传过此文件，往数据库添加一条绑定记录
            if (souceid == null) {
                logService.save(responseid, uploadFile);
            }
            RandomAccessFile fileOutStream = new RandomAccessFile(uploadFile, "r");
            // 查找上次传送的最终位置，并从这开始传送
            fileOutStream.seek(Integer.valueOf(position));
            byte[] buffer = new byte[1024];
            int len = -1;
            // 初始化上传的数据长度
            int length = Integer.valueOf(position);
            while ((len = fileOutStream.read(buffer)) != -1) {
                outStream.write(buffer, 0, len);
                // 设置长传数据长度
                length += len;
                listener.onUploadSize(length);
            }
            fileOutStream.close();
            outStream.close();
            inStream.close();
            socket.close();
            // 判断上传完则删除数据
            if (length == uploadFile.length())
                logService.delete(uploadFile);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public interface UploadProgressListener{
        void onUploadSize(int size);
    }
}

 
 下面是多线程下载

SmartDownloadActivity.java

package com.hao;

import java.io.File;

import com.hao.R;
import com.hao.R.id;
import com.hao.R.layout;
import com.hao.download.SmartFileDownloader;
import com.hao.download.SmartFileDownloader.SmartDownloadProgressListener;
import com.hao.util.ConstantValues;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

/**
 *
 * @author Administrator
 *
 */
public class SmartDownloadActivity extends Activity {
    private ProgressBar downloadbar;
    private TextView resultView;
    private String path = ConstantValues.DOWNLOAD_URL;
    SmartFileDownloader loader;
    private Handler handler = new Handler() {
        @Override
        // 信息
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 1:
                int size = msg.getData().getInt("size");
                downloadbar.setProgress(size);
                float result = (float) downloadbar.getProgress() / (float) downloadbar.getMax();
                int p = (int) (result * 100);
                resultView.setText(p + "%");
                if (downloadbar.getProgress() == downloadbar.getMax())
                    Toast.makeText(SmartDownloadActivity.this, "下载成功", 1).show();
                break;
            case -1:
                Toast.makeText(SmartDownloadActivity.this, msg.getData().getString("error"), 1).show();
                break;
            }

        }
    };

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.download);

        Button button = (Button) this.findViewById(R.id.button);
        Button closeConn = (Button) findViewById(R.id.closeConn);
        closeConn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if(loader != null){
                    finish();
                }else{
                    Toast.makeText(SmartDownloadActivity.this, "还没有开始下载，不能暂停", 1).show();
                }
            }
        });
        downloadbar = (ProgressBar) this.findViewById(R.id.downloadbar);
        resultView = (TextView) this.findViewById(R.id.result);
        resultView.setText(path);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                    download(path, ConstantValues.FILE_PATH);
                } else {
                    Toast.makeText(SmartDownloadActivity.this, "没有SDCard", 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
    private void download(final String path, final File dir) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    loader = new SmartFileDownloader(SmartDownloadActivity.this, path, dir, 3);
                    int length = loader.getFileSize();// 获取文件的长度
                    downloadbar.setMax(length);
                    loader.download(new SmartDownloadProgressListener() {
                        @Override
                        public void onDownloadSize(int size) {// 可以实时得到文件下载的长度
                            Message msg = new Message();
                            msg.what = 1;
                            msg.getData().putInt("size", size);
                            handler.sendMessage(msg);
                        }
                    });
                } catch (Exception e) {
                    Message msg = new Message();// 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

    }
}

这个单个的下载线程

 SmartDownloadThread.java

package com.hao.download;

import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

import android.util.Log;

/**
 * 线程下载
 * @author Administrator
 *
 */
public class SmartDownloadThread extends Thread {
    private static final String TAG = "SmartDownloadThread";
    private File saveFile;
    private URL downUrl;
    private int block;
    /*  *下载开始位置 */
    private int threadId = -1;
    private int downLength;
    private boolean finish = false;
    private SmartFileDownloader downloader;

    public SmartDownloadThread(SmartFileDownloader downloader, URL downUrl,
            File saveFile, int block, int downLength, int threadId) {
        this.downUrl = downUrl;
        this.saveFile = saveFile;
        this.block = block;
        this.downloader = downloader;
        this.threadId = threadId;
        this.downLength = downLength;
    }

    @Override
    public void run() {
        if (downLength < block) {// 未下载完成
            try {
                HttpURLConnection http = (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");
                int startPos = block * (threadId - 1) + downLength;// 开始位置
                int endPos = 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; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
                http.setRequestProperty("Connection", "Keep-Alive");

                InputStream inStream = http.getInputStream();
                byte[] buffer = new byte[1024];
                int offset = 0;
                print("Thread " + this.threadId + " start download from position " + startPos);
                RandomAccessFile threadfile = new RandomAccessFile(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 + " download finish");
                this.finish = true;
            } catch (Exception e) {
                this.downLength = -1;
                print("Thread " + this.threadId + ":" + e);
            }
        }
    }

    private static void print(String msg) {
        Log.i(TAG, msg);
    }

    /**
     * 下载是否完成
     * @return
     */
    public boolean isFinish() {
        return finish;
    }

    /**
     * 已经下载的内容大小
     * @return 如果返回值为-1,代表下载失败
     */
    public long getDownLength() {
        return downLength;
    }
}

 总得下载线程

SmartFileDownloader.java

package com.hao.download;

import java.io.File;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.hao.db.DownloadFileService;

import android.content.Context;
import android.util.Log;

/**
 * 文件下载主程序
 * @author Administrator
 *
 */
public class SmartFileDownloader {
    private static final String TAG = "SmartFileDownloader";
    private Context context;
    private DownloadFileService fileService;
    /* 已下载文件长度 */
    private int downloadSize = 0;
    /* 原始文件长度 */
    private int fileSize = 0;
    /*原始文件名*/
    private String fileName;
    /* 线程数 */
    private SmartDownloadThread[] threads;
    /* 本地保存文件 */
    private File saveFile;
    /* 缓存各线程下载的长度 */
    private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();
    /* 每条线程下载的长度 */
    private int block;
    /* 下载路径 */
    private String downloadUrl;

    /**
     * 获取文件名
     */
    public String getFileName(){
        return this.fileName;
    }
    /**
     * 获取线程数
     */
    public int getThreadSize() {
        return threads.length;
    }

    /**
     * 获取文件大小
     * @return
     */
    public int getFileSize() {
        return fileSize;
    }

    /**
     * 累计已下载大小
     * @param size
     */
    protected synchronized void append(int size) {
        downloadSize += size;
    }

    /**
     * 更新指定线程最后下载的位置
     * @param threadId 线程id
     * @param pos 最后下载的位置
     */
    protected void update(int threadId, int pos) {
        this.data.put(threadId, pos);
    }

    /**
     * 保存记录文件
     */
    protected synchronized void saveLogFile() {
        this.fileService.update(this.downloadUrl, this.data);
    }

    /**
     * 构建文件下载器
     * @param downloadUrl 下载路径
     * @param fileSaveDir 文件保存目录
     * @param threadNum 下载线程数
     */
    public SmartFileDownloader(Context context, String downloadUrl,
            File fileSaveDir, int threadNum) {
        try {
            this.context = context;
            this.downloadUrl = downloadUrl;
            fileService = new DownloadFileService(this.context);
            URL url = new URL(this.downloadUrl);
            if (!fileSaveDir.exists()) fileSaveDir.mkdirs();
            this.threads = new SmartDownloadThread[threadNum];
            HttpURLConnection conn = (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; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
            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)
                    throw new RuntimeException("Unkown file size ");

                fileName = getFileName(conn);
                this.saveFile = new File(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());
                }
                //划分每个线程下载文件长度
                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 (int i = 0; i < this.threads.length; i++) {
                        this.downloadSize += this.data.get(i + 1);
                    }
                    print("已经下载的长度" + this.downloadSize);
                }
            } else {
                throw new RuntimeException("server no response ");
            }
        } catch (Exception e) {
            print(e.toString());
            throw new RuntimeException("don't connection this url");
        }
    }

    /**
     * 获取文件名
     */
    private String getFileName(HttpURLConnection conn) {
        String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1);//链接的最后一个/就是文件名
        if (filename == null || "".equals(filename.trim())) {// 如果获取不到文件名称
            for (int i = 0;; i++) {
                String mine = conn.getHeaderField(i);
                print("ConnHeader:"+mine+" ");
                if (mine == null)
                    break;
                if ("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())) {
                    Matcher m = Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase());
                    if (m.find())
                        return m.group(1);
                }
            }
            filename = UUID.randomUUID() + ".tmp";// 默认取一个文件名
        }
        return filename;
    }

    /**
     * 开始下载文件
     *
     * @param listener
     *            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
     * @throws Exception
     */
    public int download(SmartDownloadProgressListener listener)
            throws Exception {
        try {
            RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw");
            if (this.fileSize > 0)
                randOut.setLength(this.fileSize);
            randOut.close();
            URL url = new URL(this.downloadUrl);
            if (this.data.size() != this.threads.length) {
                this.data.clear();// 清除数据
                for (int i = 0; i < this.threads.length; i++) {
                    this.data.put(i + 1, 0);
                }
            }
            for (int i = 0; i < this.threads.length; i++) {
                int downLength = 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[i] = new SmartDownloadThread(this, url,
                            this.saveFile, this.block, this.data.get(i + 1), i + 1);
                    this.threads[i].setPriority(7);
                    this.threads[i].start();
                } else {
                    this.threads[i] = null;
                }
            }
            this.fileService.save(this.downloadUrl, this.data);
            boolean notFinish = 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 (int i = 0; i < this.threads.length; i++) {
                    if (this.threads[i] != null && !this.threads[i].isFinish()) {
                        notFinish = true;// 下载没有完成
                        if (this.threads[i].getDownLength() == -1) {// 如果下载失败,再重新下载
                            this.threads[i] = new SmartDownloadThread(this,
                                    url, this.saveFile, this.block, this.data.get(i + 1), i + 1);
                            this.threads[i].setPriority(7);
                            this.threads[i].start();
                        }
                    }
                }
                if (listener != null)
                    listener.onDownloadSize(this.downloadSize);
            }
            fileService.delete(this.downloadUrl);
        } catch (Exception e) {
            print(e.toString());
            throw new Exception("file download fail");
        }
        return this.downloadSize;
    }

    /**
     * 获取Http响应头字段
     *
     * @param http
     * @return
     */
    public static Map<String, String> getHttpResponseHeader(
            HttpURLConnection http) {
        Map<String, String> header = new LinkedHashMap<String, String>();
        for (int i = 0;; i++) {
            String mine = http.getHeaderField(i);
            if (mine == null)
                break;
            header.put(http.getHeaderFieldKey(i), mine);
        }
        return header;
    }

    /**
     * 打印Http头字段
     *
     * @param http
     */
    public static void printResponseHeader(HttpURLConnection http) {
        Map<String, String> header = getHttpResponseHeader(http);
        for (Map.Entry<String, String> entry : header.entrySet()) {
            String key = entry.getKey() != null ? entry.getKey() + ":" : "";
            print(key + entry.getValue());
        }
    }

    // 打印日志
    private static void print(String msg) {
        Log.i(TAG, msg);
    }

    public interface SmartDownloadProgressListener {
        public void onDownloadSize(int size);
    }
}

 
 好了这里只是将主要的代码分享出来，主要是为了了解他的基本流程，然后自己可以扩展，和优化