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多线程下载文件

来源：程序员人生发布时间：2016-07-04 09:01:23 阅读次数：2405次

多线程下载文件

DBOpenHelper.java

package com.amlapp.update.otaupgrade.download;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBOpenHelper extends SQLiteOpenHelper {
    // 数据库文件的文件名 
    private static final String DBNAME = "download.db";
    // 数据库的版本号
    private static final int VERSION = 1;

    public DBOpenHelper(Context context) {
        super(context, DBNAME, null, VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS filedownlog (id integer primary key autoincrement, downpath varchar(100), threadid INTEGER, downlength INTEGER)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS filedownlog");
        onCreate(db);
    }
}

DownloadThread.java

package com.amlapp.update.otaupgrade.download;

import java.io.BufferedInputStream; 
import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import android.util.Log;

public class DownloadThread extends Thread {
    private static final String TAG = "DownloadThread";
    /** 本地保存文件 */
    private File saveFile;
    /** 下载路径 */
    private URL downUrl;
    /** 该线程要下载的长度 */
    private int block;
    /** 线程ID */
    private int threadId = -1;
    /** 该线程已下载的长度 */
    private int downLength;
    /** 是不是下载完成 */
    private boolean finish = false;
    /** 文件下载器 */
    private FileDownloader downloader;

    /***
     * 构造方法
     */
    public DownloadThread(FileDownloader 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;
    }

    /**
     * 线程主方法
     */
    @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", "UTF⑻");
                // 该线程开始下载位置
                int startPos = block * (threadId - 1) + downLength;
                // 该线程下载结束位置
                int endPos = block * threadId - 1;
                // 设置获得实体数据的范围
                http.setRequestProperty("Range", "bytes=" + startPos + "-"
                        + endPos);
                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");
                /****/
                System.out.println("DownloadThread http.getResponseCode()："
                        + http.getResponseCode());
                if (http.getResponseCode() == 206) {
                    /***
                     * //获得输入流 InputStream inStream = http.getInputStream();
                     * byte[] buffer = new byte[1024]; int offset = 0;
                     * print("Thread " + this.threadId +
                     * " start download from position " + startPos);
                     * 
                     * // rwd: 打开以便读取和写入，对 "rw"，还要求对文件内容的每一个更新都同步写入到基础存储装备。
                     * //对Android移动装备1定要注意同步，否则当移动装备断电的话会丢失数据 RandomAccessFile
                     * threadfile = new RandomAccessFile( this.saveFile, "rwd");
                     * //直接移动到文件开始位置下载的 threadfile.seek(startPos); while
                     * (!downloader.getExit() && (offset = inStream.read(buffer,
                     * 0, 1024)) != ⑴) { threadfile.write(buffer, 0,
                     * offset);//开始写入数据到文件 downLength += offset; //该线程和下载的长度增加
                     * downloader.update(this.threadId,
                     * downLength);//修改数据库中该线程已下载的数据长度
                     * downloader.append(offset);//文件下载器已下载的总长度增加 }
                     * threadfile.close();
                     * 
                     * print("Thread " + this.threadId + " download finish");
                     * this.finish = true;
                     **/
                    // 获得输入流
                    InputStream inStream = http.getInputStream();
                    BufferedInputStream bis = new BufferedInputStream(inStream);
                    byte[] buffer = new byte[1024 * 4];
                    int offset = 0;
                    RandomAccessFile threadfile = new RandomAccessFile(
                            this.saveFile, "rwd");
                    // 获得RandomAccessFile的FileChannel
                    FileChannel outFileChannel = threadfile.getChannel();
                    // 直接移动到文件开始位置下载的
                    outFileChannel.position(startPos);
                    // 分配缓冲区的大小
                    while (!downloader.getExit()
                            && (offset = bis.read(buffer)) != -1) {
                        outFileChannel
                                .write(ByteBuffer.wrap(buffer, 0, offset));// 开始写入数据到文件
                        downLength += offset; // 该线程和下载的长度增加
                        downloader.update(this.threadId, downLength);// 修改数据库中该线程已下载的数据长度
                        downloader.append(offset);// 文件下载器已下载的总长度增加
                    }
                    outFileChannel.close();
                    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);
    }

    /**
     * 下载是不是完成
     * 
     * @return
     */
    public boolean isFinish() {
        return finish;
    }

    /**
     * 已下载的内容大小
     * 
     * @return 如果返回值为⑴,代表下载失败
     */
    public long getDownLength() {
        return downLength;
    }
}

FileDownloader.java

package com.amlapp.update.otaupgrade.download;

import java.io.BufferedReader;
import java.io.File; 
import java.io.InputStreamReader;
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 org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams; 

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

/**
 * 文件下载器
 */
public class FileDownloader {
    private static final String TAG = "FileDownloader";
    /** 上下文 */
    private Context context;
    /** 文件下载服务类 */
    private FileService fileService;
    /** 是不是停止下载 */
    private boolean exit;
    /** 已下载文件长度 */
    private int downloadSize = 0;
    /** 原始文件长度 */
    private int fileSize = 0;
    /** 用于下载的线程数组 */
    private DownloadThread[] 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;


    /**
     * 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 FileDownloader(Context context, String downloadUrl,
            File fileSaveDir, int threadNum) {
        try {
            this.context = context;
            this.downloadUrl = downloadUrl;
            fileService = new FileService(this.context);
            // 根据指定的下载路径，生成URL
            URL url = new URL(this.downloadUrl);
            if (!fileSaveDir.exists())
                fileSaveDir.mkdirs();// 如果保存路径不存在，则新建1个目录
            // 根据指定的线程数来新建线程数组
            this.threads = new DownloadThread[threadNum];
            // 打开HttpURLConnection
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            // 设置 HttpURLConnection的断开时间
            conn.setConnectTimeout(5 * 1000);
            // 设置 HttpURLConnection的要求方式
            conn.setRequestMethod("GET");
            // 设置 HttpURLConnection的接收的文件类型
            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, */*");
            // 设置 HttpURLConnection的接收语音
            conn.setRequestProperty("Accept-Language", "zh-CN");
            // 指定要求uri的源资源地址
            conn.setRequestProperty("Referer", downloadUrl);
            // 设置 HttpURLConnection的字符编码
            conn.setRequestProperty("Charset", "UTF⑻");
            // 检查阅读页面的访问者在用甚么操作系统（包括版本号）阅读器（包括版本号）和用户个人偏好
            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();
            // 打印Http协议头
            printResponseHeader(conn);
            // 如果返回的状态码为200表示正常
            //System.out.println("conn.getResponseCode()："+conn.getResponseCode());
            if (conn.getResponseCode() == 200) {
                this.fileSize = conn.getContentLength();// 根据响应获得文件大小
                if (this.fileSize <= 0)
                    throw new RuntimeException("Unkown file size ");

                String filename = getFileName(conn);// 获得文件名称
                this.saveFile = new File(fileSaveDir, filename);// 构建保存文件
                Map<Integer, Integer> logdata = fileService
                        .getData(downloadUrl);// 获得下载记录
                if (logdata.size() > 0) {// 如果存在下载记录
                    for (Map.Entry<Integer, Integer> entry : logdata.entrySet())
                        data.put(entry.getKey(), entry.getValue());// 把各条线程已下载的数据长度放入data中
                }
                if (this.data.size() == this.threads.length) {// 下面计算所有线程已下载的数据总长度
                    for (int i = 0; i < this.threads.length; i++) {
                        this.downloadSize += this.data.get(i + 1);
                    }
                    print("已下载的长度" + this.downloadSize);
                }
                // 计算每条线程下载的数据长度
                this.block = (this.fileSize % this.threads.length) == 0 ? this.fileSize
                        / this.threads.length
                        : this.fileSize / this.threads.length + 1;
            } else {
                throw new RuntimeException("server no response ");
            }
        } catch (Exception e) {
            print(e.toString());
            throw new RuntimeException("don't connection this url");
        }
    }

    /**
     * 获得线程数
     */
    public int getThreadSize() {
        return threads.length;
    }

    /**
     * 退出下载
     */
    public void exit() {
        this.exit = true;
    }

    /**
     * 是不是退出下载
     */
    public boolean getExit() {
        return this.exit;
    }

    /**
     * 获得文件大小
     */
    public int getFileSize() {
        return fileSize;
    }

    /**
     * 累计已下载大小
     * 该方法在具体某个线程下载的时候会被调用
     */
    protected synchronized void append(int size) {
        downloadSize += size;
    }

    /**
     * 更新指定线程最后下载的位置
     * 该方法在具体某个线程下载的时候会被调用
     * @param threadId
     *            线程id
     * @param pos
     *            最后下载的位置
     */
    protected synchronized void update(int threadId, int pos) {
        // 缓存各线程下载的长度
        this.data.put(threadId, pos);
        // 更新数据库中的各线程下载的长度
        this.fileService.update(this.downloadUrl, threadId, pos);
    }



    /**
     * 获得文件名
     * 
     * @param conn
     *            Http连接
     */
    private String getFileName(HttpURLConnection conn) {
        String filename = this.downloadUrl.substring(this.downloadUrl
                .lastIndexOf('/') + 1);// 截取下载路径中的文件名
        // 如果获得不到文件名称
        if (filename == null || "".equals(filename.trim())) {
            // 通过截取Http协议头分析下载的文件名
            for (int i = 0;; i++) {
                String mine = conn.getHeaderField(i);
                if (mine == null)
                    break;
                /**
                 * Content-disposition 是 MIME 协议的扩大，MIME 协议唆使 MIME
                 * 用户代理如何显示附加的文件。
                 * Content-Disposition就是当用户想把要求所得的内容存为1个文件的时候提供1个默许的文件名
                 * 协议头中的Content-Disposition格式以下：
                 * Content-Disposition","attachment;filename=FileName.txt");
                 */
                if ("content-disposition".equals(conn.getHeaderFieldKey(i)
                        .toLowerCase())) {
                    // 通过正则表达式匹配出文件名
                    Matcher m = Pattern.compile(".*filename=(.*)").matcher(
                            mine.toLowerCase());
                    // 如果匹配到了文件名
                    if (m.find())
                        return m.group(1);// 返回匹配到的文件名
                }
            }
            // 如果还是匹配不到文件名，则默许取1个随机数文件名
            filename = UUID.randomUUID() + ".tmp";
        }
        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(DownloadProgressListener 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);
            // 如果本来未曾下载或本来的下载线程数与现在的线程数不1致
            if (this.data.size() != this.threads.length) {
                this.data.clear();// 清除原来的线程数组
                for (int i = 0; i < this.threads.length; i++) {
                    this.data.put(i + 1, 0);// 初始化每条线程已下载的数据长度为0
                }
                this.downloadSize = 0;
            }
            //循环遍历线程数组
            for (int i = 0; i < this.threads.length; i++) {
                int downLength = this.data.get(i + 1); // 获得当前线程下载的文件长度
                // 判断线程是不是已完成下载,否则继续下载
                if (downLength < this.block
                        && this.downloadSize < this.fileSize) {
                    //启动线程开始下载
                    this.threads[i] = new DownloadThread(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;
                }
            }
            //如果存在下载记录，从数据库中删除它们
            fileService.delete(this.downloadUrl);
            //重新保存下载的进度到数据库
            fileService.save(this.downloadUrl, this.data);
            boolean notFinish = true;// 下载未完成
            while (notFinish) {// 循环判断所有线程是不是完成下载
                Thread.sleep(900);
                notFinish = false;// 假定全部线程下载完成
                for (int i = 0; i < this.threads.length; i++) {
                    if (this.threads[i] != null && !this.threads[i].isFinish()) {// 如果发现线程未完成下载
                        notFinish = true;// 设置标志为下载没有完成
                        // 如果下载失败,再重新下载
                        if (this.threads[i].getDownLength() == -1) {
                            this.threads[i] = new DownloadThread(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,this.fileSize);// 通知目前已下载完成的数据长度
            }
            // 如果下载完成
            if (downloadSize == this.fileSize)
                fileService.delete(this.downloadUrl);// 下载完成删除记录
        } catch (Exception e) {
            print(e.toString());
            throw new Exception("file download error");
        }
        return this.downloadSize;
    }

    /**
     * 获得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());
        }
    }


    /**
    * 获得网址内容
    * @param url
    * @return
    * @throws Exception
    */
    public static String getContent(String url) throws Exception{
        StringBuilder sb = new StringBuilder();

        HttpClient client = new DefaultHttpClient();
        HttpParams httpParams = client.getParams();
        //设置网络超时参数
        HttpConnectionParams.setConnectionTimeout(httpParams, 3000);
        HttpConnectionParams.setSoTimeout(httpParams, 5000);
        HttpResponse response = client.execute(new HttpGet(url));
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(entity.getContent(), "UTF⑻"), 8192);

            String line = null;
            while ((line = reader.readLine())!= null){
                sb.append(line + "\n");
            }
            reader.close();
        }
        return sb.toString();
    } 



    /**
     * 打印信息
     * @param msg  信息
     */
    private static void print(String msg) {
        Log.i(TAG, msg);
    }

    /** 
     * 下载进度监听接口
     */
    public interface DownloadProgressListener {
        /**
         *下载的进度 
         */
        public void onDownloadSize(int size,int fileSize);
    }

}

FileService.java

package com.amlapp.update.otaupgrade.download;

import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

/**
 * 文件下载服务类
 */
public class FileService { 
    private DBOpenHelper openHelper;

    public FileService(Context context) {
        openHelper = new DBOpenHelper(context);
    }

    /**
     * 获得每条线程已下载的文件长度
     * 
     * @param path
     * @return
     */
    public Map<Integer, Integer> getData(String path) {
        SQLiteDatabase db = openHelper.getReadableDatabase();
        Cursor cursor = db
                .rawQuery(
                        "select threadid, downlength from filedownlog where downpath=?",
                        new String[] { path });
        Map<Integer, Integer> data = new HashMap<Integer, Integer>();
        while (cursor.moveToNext()) {
            data.put(cursor.getInt(0), cursor.getInt(1));
        }
        cursor.close();
        db.close();
        return data;
    }

    /**
     * 保存每条线程已下载的文件长度
     * 
     * @param path
     * @param map
     */
    public void save(String path, Map<Integer, Integer> map) {// int threadid,
                                                                // int position
        SQLiteDatabase db = openHelper.getWritableDatabase();
        db.beginTransaction();
        try {
            for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
                db.execSQL(
                        "insert into filedownlog(downpath, threadid, downlength) values(?,?,?)",
                        new Object[] { path, entry.getKey(), entry.getValue() });
            }
            db.setTransactionSuccessful();
        } finally {
            db.endTransaction();
        }
        db.close();
    }

    /**
     * 实时更新每条线程已下载的文件长度
     * 
     * @param path
     * @param map
     */
    public void update(String path, int threadId, int pos) {
        SQLiteDatabase db = openHelper.getWritableDatabase();
        db.execSQL(
                "update filedownlog set downlength=? where downpath=? and threadid=?",
                new Object[] { pos, path, threadId });
        db.close();
    }

    /**
     * 当文件下载完成后，删除对应的下载记录
     * 
     * @param path
     */
    public void delete(String path) {
        SQLiteDatabase db = openHelper.getWritableDatabase();
        db.execSQL("delete from filedownlog where downpath=?",
                new Object[] { path });
        db.close();
    }
}

测试Activity：

package com.moonlight.projectorforge;

import java.io.File;

import com.amlapp.update.otaupgrade.download.FileDownloader;
import com.amlapp.update.otaupgrade.download.FileDownloader.DownloadProgressListener;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        new AsyncTask<String, Integer, Integer>() {
            private String downloadUrl = "http://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=asda&step_word=&pn=1&spn=0&di=145126455210&pi=&rn=1&tn=baiduimagedetail&is=&istype=0&ie=utf⑻&oe=utf⑻&in=&cl=2&lm=⑴&st=undefined&cs=3541143192%2C3632970612&os=3611388031%2C2854364844&simid=3432062895%2C349837288&adpicid=0&ln=1976&fr=&fmq=1467017028245_R&fm=&ic=undefined&s=undefined&se=&sme=&tab=0&width=&height=&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fwww.hereinuk.com%2Fwp-content%2Fuploads%2F2014%2F07%2Fasda.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3F4r_z%26e3Bojtxtg_z%26e3Bqq_z%26e3Bv54AzdH3Ff%3F__ktz%3DMzA9OTQaMTUzOA%3D%3D%264t1%3Ddaan8b99m%26t1x%3Dd%26fg%3Dkwknnw0ud19bv989jbm0c8m8dcknkdn0&gsm=0&rpstart=0&rpnum=0";
            private File fileSaveDir = new File("/storage/external_storage/sda1/");
            private int threadNum = 5;
            private int totalSize;

            @Override
            protected Integer doInBackground(String... params) {
                FileDownloader loader = new FileDownloader(MainActivity.this, downloadUrl, fileSaveDir, threadNum);
                try {
                    loader.download(new DownloadProgressListener() {
                        @Override
                        public void onDownloadSize(int size, int fileSize) {
                            totalSize = fileSize;
                            publishProgress(size);
                        }
                    });
                } catch (Exception e) {
                    e.printStackTrace();
                    return -1;
                }
                return 0;
            }
            @Override
            protected void onProgressUpdate(Integer... values) {
                super.onProgressUpdate(values);
                //Todo show download progress,percentage:100f*values[0]/totalSize
            }
            @Override
            protected void onPostExecute(Integer result) {
                super.onPostExecute(result);
                if(result ==0){
                    //Todo download success
                }else{
                    //Todo download failed
                }

            }
        }.execute();
    }

}

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