学步园

前面已经讲了通过多线程下载网络文件的一部分核心代码，下面继续做我们的项目

当然如果我们做小一点的Android项目的时候可以先做界面，然后根据需要来扩展所需要的功能，当然有的时候我们宁愿先实现业务，业务功能做好了再实现界面，因为界面里面基本不含有技术，况且我们只是为了学习，界面不需要多美观的，能用就行，OK，继续

先做数据库这层

关于建Android项目方法的截图就省略了，我用的模拟器版本是2.3.3，至今为至最新的吧

首先建一个类DBOpenHelper继续自SQLiteOpenHelper

package com.studio.service;

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

public class DBOpenHelper extends SQLiteOpenHelper {
private static final String DBNAME = "download.db";
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);
    }

}

这里定义的数据名字叫download.db,版本号为1，表名filedownlog,里面有三个字段，一个id,主键，下载路径downpath，线程ID和一个下载长度downlength

然后建一个FileService类

package com.studio.service;

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

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

/**
 * 业务bean
 * 
*/
public class FileService {

private DBOpenHelper openHelper;

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

/**
     * 获取每条线程已经下载的文件长度
     * 
     * @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;
    }

/**
     * 保存每条线程已经下载的文件长度
     * 
     * @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经下载的文件长度
     * 
     * @param path
     * @param map
*/
public void update(String path, Map<Integer, Integer> map) {
        SQLiteDatabase db = openHelper.getWritableDatabase();
        db.beginTransaction();
try {
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
                db.execSQL(
"update filedownlog set downlength=? where downpath=? and threadid=?",
new Object[] { 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
     * 
     * @param path
*/
public void delete(String path) {
        SQLiteDatabase db = openHelper.getWritableDatabase();
        db.execSQL("delete from filedownlog where downpath=?",
new Object[] { path });
        db.close();
    }
}

类中都有相应的注释的，看不懂可以慢慢看……

因为要用到进度条，所以先把进度条建了

package com.studio.net.download;

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

这里我们定义了一个进度条监听接口，由实现此接口的类来调用onDownloadSize()方法

新建一个类DownloadThread继承自Thread

package com.studio.net.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;

public class DownloadThread extends Thread {
private static final String TAG = "DownloadThread";
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 FileDownloader downloader;

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;
    }

    @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.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;
    }
}

再建一个文件下载器FileDownloader类

package com.studio.net.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.studio.service.FileService;
import android.content.Context;
import android.util.Log;

public class FileDownloader {
private static final String TAG = "FileDownloader";
private Context context;
private FileService fileService;
/* 已下载文件长度 */
private int downloadSize = 0;
/* 原始文件长度 */
private int fileSize = 0;
/* 线程数 */
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;
/**
     * 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 synchronized void update(int threadId, int pos) {
this.data.put(threadId, pos);
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 FileDownloader(Context context, String downloadUrl,
            File fileSaveDir, int threadNum) {
try {
this.context = context;
this.downloadUrl = downloadUrl;
            fileService = new FileService(this.context);
            URL url = new URL(this.downloadUrl);
if (!fileSaveDir.exists())
                fileSaveDir.mkdirs();
this.threads = new DownloadThread[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 ");
                String filename = getFileName(conn);// 获取文件名称
                this.saveFile = new File(fileSaveDir, filename);// 构建保存文件
                Map<Integer, Integer> logdata = fileService
                        .getData(downloadUrl);// 获取下载记录
                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());// 把各条线程已经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经下载的数据长度
                    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);
                }
// 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");
        }
    }
/**
     * 获取文件名
*/
private String getFileName(HttpURLConnection conn) {
        String filename = this.downloadUrl.substring(this.downloadUrl
                .lastIndexOf('/') + 1);
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);
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(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);
if (this.data.size() != this.threads.length) {
this.data.clear();
for (int i = 0; i < this.threads.length; i++) {
this.data.put(i + 1, 0);// 初始化每条线程已经下载的数据长度为0
                }
            }
for (int i = 0; i < this.threads.length; i++) {// 开启线程进行下载
                int downLength = this.data.get(i + 1);
if (downLength < this.block
&& this.downloadSize < this.fileSize) {// 判断线程是否已经完成下载,否则继续下载
                    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;
                }
            }
this.fileService.save(this.downloadUrl, this.data);












														
							

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