<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:paddingBottom="@dimen/activity_vertical_margin" 
 android:paddingLeft="@dimen/activity_horizontal_margin" 
 android:paddingRight="@dimen/activity_horizontal_margin" 
 android:paddingTop="@dimen/activity_vertical_margin" 
 android:orientation="vertical" 
 tools:context=".MainActivity" > 
 
 <TextView 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:text="下载路径" /> 
 
 <EditText 
 android:id="@+id/ed_path" 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:text="http://192.168.0.170:8080/web/youdao.exe"/> 
 <Button 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:text="下载" 
 android:onClick="download"/> 
 
 <ProgressBar 
 android:id="@+id/pb" 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 style="@android:style/Widget.ProgressBar.Horizontal"/> 
 
 <TextView 
 android:id="@+id/tv_info" 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="下载:0%"/> 
 
</LinearLayout> 

package com.example.inter; 
 
/** 
 * 自定义进度条监听器 
 * @author liuyazhuang 
 * 
 */ 
public interface ProgressBarListener { 
 /** 
 * 获取文件的长度 
 * @param length 
 */ 
 void getMax(int length); 
 /** 
 * 获取每次下载的长度 
 * @param length 
 */ 
 void getDownload(int length); 
} 

package com.example.db; 
 
import android.content.Context; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteDatabase.CursorFactory; 
import android.database.sqlite.SQLiteOpenHelper; 
 
/** 
 * 数据库相关类 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadDBHelper extends SQLiteOpenHelper { 
 /** 
 * 数据库名称 
 */ 
 private static final String NAME = "download.db"; 
 /** 
 * 原有的构造方法 
 * @param context 
 * @param name 
 * @param factory 
 * @param version 
 */ 
 public DownloadDBHelper(Context context, String name, 
 CursorFactory factory, int version) { 
 super(context, name, factory, version); 
 } 
 /** 
 * 重载构造方法 
 * @param context 
 */ 
 public DownloadDBHelper(Context context){ 
 super(context, NAME, null, 1); 
 } 
 
 /** 
 * 创建数据库时调用 
 */ 
 @Override 
 public void onCreate(SQLiteDatabase db) { 
 db.execSQL("create table download(_id integer primary key autoincrement," + 
  "path text," + 
  "threadid integer," + 
  "downloadlength integer)"); 
 
 } 
 /** 
 * 更新数据库时调用 
 */ 
 @Override 
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
 
 } 
 
} 

package com.example.provider; 
 
import com.example.db.DownloadDBHelper; 
 
import android.content.ContentProvider; 
import android.content.ContentValues; 
import android.content.UriMatcher; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.net.Uri; 
 
/** 
 * 自定义ContentProvider实例 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadProvider extends ContentProvider { 
 //实例化UriMatcher对象 
 private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH); 
 //配置访问规则 
 private static final String AUTHORITY = "download"; 
 //自定义常量 
 private static final int DOWANLOAD = 10; 
 static{ 
 //添加匹配的规则 
 matcher.addURI(AUTHORITY, "download", DOWANLOAD); 
 } 
 private SQLiteOpenHelper mOpenHelper; 
 @Override 
 public boolean onCreate() { 
 mOpenHelper = new DownloadDBHelper(getContext()); 
 return false; 
 } 
 
 @Override 
 public Cursor query(Uri uri, String[] projection, String selection, 
 String[] selectionArgs, String sortOrder) { 
 // TODO Auto-generated method stub 
 Cursor ret = null; 
 SQLiteDatabase db = mOpenHelper.getReadableDatabase(); 
 int code = matcher.match(uri); 
 switch (code) { 
 case DOWANLOAD: 
 ret = db.query("download", projection, selection, selectionArgs, null, null, sortOrder); 
 break; 
 
 default: 
 break; 
 } 
 return ret; 
 } 
 
 @Override 
 public String getType(Uri uri) { 
 // TODO Auto-generated method stub 
 return null; 
 } 
 
 @Override 
 public Uri insert(Uri uri, ContentValues values) { 
 // TODO Auto-generated method stub 
 SQLiteDatabase db = mOpenHelper.getWritableDatabase(); 
 int code = matcher.match(uri); 
 switch (code) { 
 case DOWANLOAD: 
 db.insert("download", "_id", values); 
 break; 
 
 default: 
 break; 
 } 
 return null; 
 } 
 
 @Override 
 public int delete(Uri uri, String selection, String[] selectionArgs) { 
 SQLiteDatabase db = mOpenHelper.getWritableDatabase(); 
 int code = matcher.match(uri); 
 switch (code) { 
 case DOWANLOAD: 
 db.delete("download", selection, selectionArgs); 
 break; 
 
 default: 
 break; 
 } 
 return 0; 
 } 
 
 @Override 
 public int update(Uri uri, ContentValues values, String selection, 
 String[] selectionArgs) { 
 SQLiteDatabase db = mOpenHelper.getWritableDatabase(); 
 int code = matcher.match(uri); 
 switch (code) { 
 case DOWANLOAD: 
 db.update("download", values, selection, selectionArgs); 
 break; 
 
 default: 
 break; 
 } 
 return 0; 
 } 
 
} 

package com.example.domain; 
 
/** 
 * 支持断点续传时， 
 * 要保存到数据库的信息 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadInfo { 
 //主键id 
 private int _id; 
 //保存路径 
 private String path; 
 //线程的标识id 
 private String threadId; 
 //下载文件的大小 
 private int downloadSize; 
 
 public DownloadInfo() { 
 super(); 
 } 
 
 public DownloadInfo(int _id, String path, String threadId, int downloadSize) { 
 super(); 
 this._id = _id; 
 this.path = path; 
 this.threadId = threadId; 
 this.downloadSize = downloadSize; 
 } 
 
 public int get_id() { 
 return _id; 
 } 
 public void set_id(int _id) { 
 this._id = _id; 
 } 
 public String getPath() { 
 return path; 
 } 
 public void setPath(String path) { 
 this.path = path; 
 } 
 public String getThreadId() { 
 return threadId; 
 } 
 public void setThreadId(String threadId) { 
 this.threadId = threadId; 
 } 
 public int getDownloadSize() { 
 return downloadSize; 
 } 
 public void setDownloadSize(int downloadSize) { 
 this.downloadSize = downloadSize; 
 } 
} 

package com.example.dao; 
 
import android.content.ContentResolver; 
import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.net.Uri; 
 
import com.example.domain.DownloadInfo; 
 
/** 
 * 保存下载文件信息的dao类 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadDao { 
 
 /** 
 * ContentResolver对象 
 */ 
 private ContentResolver cr; 
 
 public DownloadDao(Context context){ 
 this.cr = context.getContentResolver(); 
 } 
 /** 
 * 保存下载信息记录 
 * @param info 
 */ 
 public void save(DownloadInfo info){ 
 Uri uri = Uri.parse("content://download/download"); 
 ContentValues values = new ContentValues(); 
 values.put("path", info.getPath()); 
 values.put("threadid", info.getThreadId()); 
 cr.insert(uri, values); 
 } 
 
 /** 
 * 更新下载信息记录 
 * @param info 
 */ 
 public void update(DownloadInfo info){ 
 Uri uri = Uri.parse("content://download/download"); 
 ContentValues values = new ContentValues(); 
 values.put("downloadlength", info.getDownloadSize()); 
 values.put("threadid", info.getThreadId()); 
 cr.update(uri, values, " path = ? and threadid = ? ", new String[]{info.getPath(), info.getThreadId()}); 
 } 
 /** 
 * 删除下载信息记录 
 * @param info 
 */ 
 public void delete(DownloadInfo info){ 
 Uri uri = Uri.parse("content://download/download"); 
 cr.delete(uri, " path = ? and threadid = ? ", new String[]{info.getPath(), info.getThreadId()}); 
 } 
 /** 
 * 删除下载信息记录 
 * @param info 
 */ 
 public void delete(String path){ 
 Uri uri = Uri.parse("content://download/download"); 
 cr.delete(uri, " path = ? ", new String[]{path}); 
 } 
 
 /** 
 * 判断是否有下载记录 
 * @param path 
 * @return 
 */ 
 public boolean isExist(String path){ 
 boolean result = false; 
 Uri uri = Uri.parse("content://download/download"); 
 Cursor cursor = cr.query(uri, null, " path = ? ", new String[]{path}, null); 
 if(cursor.moveToNext()){ 
 result = true; 
 } 
 cursor.close(); 
 return result; 
 } 
 
 /** 
 * 计算所有的下载长度 
 * @param path 
 * @return 
 */ 
 public int queryCount(String path){ 
 int count = 0; 
 Uri uri = Uri.parse("content://download/download"); 
 Cursor cursor = cr.query(uri, new String[]{"downloadlength"}, " path = ? ", new String[]{path}, null); 
 while(cursor.moveToNext()){ 
 int len = cursor.getInt(0); 
 count += len; 
 } 
 cursor.close(); 
 return count; 
 } 
 /** 
 * 计算每个线程的下载长度 
 * @param path 
 * @return 
 */ 
 public int query(DownloadInfo info){ 
 int count = 0; 
 Uri uri = Uri.parse("content://download/download"); 
 Cursor cursor = cr.query(uri, new String[]{"downloadlength"}, " path = ? and threadid = ?", new String[]{info.getPath(), info.getThreadId()}, null); 
 while(cursor.moveToNext()){ 
 int len = cursor.getInt(0); 
 count += len; 
 } 
 cursor.close(); 
 return count; 
 } 
} 

package com.example.download; 
 
import java.io.File; 
import java.io.InputStream; 
import java.io.RandomAccessFile; 
import java.net.HttpURLConnection; 
import java.net.URL; 
 
import android.content.Context; 
 
import com.example.dao.DownloadDao; 
import com.example.domain.DownloadInfo; 
import com.example.inter.ProgressBarListener; 
 
/** 
 * 自定义线程类 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadThread extends Thread { 
 //下载的线程id 
 private int threadId; 
 //下载的文件路径 
 private String path; 
 //保存的文件 
 private File file; 
 //下载的进度条更新的监听器 
 private ProgressBarListener listener; 
 //每条线程下载的数据量 
 private int block; 
 //下载的开始位置 
 private int startPosition; 
 //下载的结束位置 
 private int endPosition; 
 
 private DownloadDao downloadDao; 
 
 public DownloadThread(int threadId, String path, File file, ProgressBarListener listener, int block, Context context) { 
 this.threadId = threadId; 
 this.path = path; 
 this.file = file; 
 this.listener = listener; 
 this.block = block; 
 this.downloadDao = new DownloadDao(context); 
 this.startPosition = threadId * block; 
 this.endPosition = (threadId + 1) * block - 1; 
 } 
 
 @Override 
 public void run() { 
 super.run(); 
 try { 
 //判断该线程是否有下载记录 
 DownloadInfo info = new DownloadInfo(); 
 info.setPath(path); 
 info.setThreadId(String.valueOf(threadId)); 
 int length = downloadDao.query(info); 
 startPosition += length; 
 //创建RandomAccessFile对象 
 RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); 
 //跳转到开始位置 
 accessFile.seek(startPosition); 
 URL url = new URL(path); 
 //打开http链接 
 HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
 //设置超时时间 
 conn.setConnectTimeout(5000); 
 //指定请求方式为GET方式 
 conn.setRequestMethod("GET"); 
 //指定下载的位置 
 conn.setRequestProperty("Range", "bytes="+startPosition + "-" + endPosition); 
 //不用再去判断状态码是否为200 
 InputStream in = conn.getInputStream(); 
 byte[] buffer = new byte[1024]; 
 int len = 0; 
 //该线程下载的总数据量 
 int count = length; 
 while((len = in.read(buffer)) != -1){ 
 accessFile.write(buffer, 0, len); 
 //更新下载进度 
 listener.getDownload(len); 
 count += len; 
 info.setDownloadSize(count); 
 //更新下载的信息 
 downloadDao.update(info); 
 } 
 accessFile.close(); 
 in.close(); 
 } catch (Exception e) { 
 // TODO: handle exception 
 e.printStackTrace(); 
 } 
 } 
} 

package com.example.download; 
 
import java.io.File; 
import java.io.RandomAccessFile; 
import java.net.HttpURLConnection; 
import java.net.URL; 
 
import android.content.Context; 
import android.os.Environment; 
 
import com.example.dao.DownloadDao; 
import com.example.domain.DownloadInfo; 
import com.example.inter.ProgressBarListener; 
 
/** 
 * 文件下载管理器 
 * @author liuyazhuang 
 * 
 */ 
public class DownloadManager { 
 //下载线程的数量 
 private static final int TREAD_SIZE = 3; 
 private File file; 
 private DownloadDao downloadDao; 
 private Context context; 
 public DownloadManager(Context context) { 
 this.context = context; 
 this.downloadDao = new DownloadDao(context); 
 } 
 
 /** 
 * 下载文件的方法 
 * @param path：下载文件的路径 
 * @param listener：自定义的下载文件监听接口 
 * @throws Exception 
 */ 
 public void download(String path, ProgressBarListener listener) throws Exception{ 
 URL url = new URL(path); 
 HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
 conn.setConnectTimeout(5000); 
 conn.setRequestMethod("GET"); 
 if(conn.getResponseCode() == 200){ 
 int filesize = conn.getContentLength(); 
 //设置进度条的最大长度 
 listener.getMax(filesize); 
 //判断下载记录是否存在 
 boolean ret = downloadDao.isExist(path); 
 if(ret){ 
 //得到下载的总长度，设置进度条的刻度 
 int count = downloadDao.queryCount(path); 
 listener.getDownload(count); 
 }else{ 
 //保存下载记录 
 for(int i = 0; i < filesize; i++){ 
  DownloadInfo info = new DownloadInfo(); 
  info.setPath(path); 
  info.setThreadId(String.valueOf(i)); 
  //保存下载的记录信息 
  downloadDao.save(info); 
 } 
 } 
 //创建一个和服务器大小一样的文件 
 file = new File(Environment.getExternalStorageDirectory(), this.getFileName(path)); 
 RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); 
 accessFile.setLength(filesize); 
 //要关闭RandomAccessFile对象 
 accessFile.close(); 
 
 //计算出每条线程下载的数据量 
 int block = filesize % TREAD_SIZE == 0 ? (filesize / TREAD_SIZE) : (filesize / TREAD_SIZE +1 ); 
 
 //开启线程下载 
 for(int i = 0; i < TREAD_SIZE; i++){ 
 new DownloadThread(i, path, file, listener, block, context).start(); 
 } 
 } 
 } 
 
 /** 
 * 截取路径中的文件名称 
 * @param path:要截取文件名称的路径 
 * @return:截取到的文件名称 
 */ 
 private String getFileName(String path){ 
 return path.substring(path.lastIndexOf("/") + 1); 
 } 
} 

package com.example.multi; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.view.Menu; 
import android.view.View; 
import android.widget.EditText; 
import android.widget.ProgressBar; 
import android.widget.TextView; 
import android.widget.Toast; 
 
import com.example.dao.DownloadDao; 
import com.example.download.DownloadManager; 
import com.example.inter.ProgressBarListener; 
 
/** 
 * MainActivity整个应用程序的入口 
 * @author liuyazhuang 
 * 
 */ 
public class MainActivity extends Activity { 
 
 protected static final int ERROR_DOWNLOAD = 0; 
 protected static final int SET_PROGRESS_MAX = 1; 
 protected static final int UPDATE_PROGRESS = 2; 
 
 private EditText ed_path; 
 private ProgressBar pb; 
 private TextView tv_info; 
 private DownloadManager manager; 
 private DownloadDao downloadDao; 
 
 //handler操作 
 private Handler mHandler = new Handler(){ 
 
 public void handleMessage(android.os.Message msg) { 
 switch (msg.what) { 
 case ERROR_DOWNLOAD: 
 //提示用户下载失败 
 Toast.makeText(MainActivity.this, "下载失败", Toast.LENGTH_SHORT).show(); 
 break; 
 case SET_PROGRESS_MAX: 
 //得到最大值 
 int max = (Integer) msg.obj; 
 //设置进度条的最大值 
 pb.setMax(max); 
 break; 
 case UPDATE_PROGRESS: 
 //获取当前下载的长度 
 int currentprogress = pb.getProgress(); 
 //获取新下载的长度 
 int len = (Integer) msg.obj; 
 //计算当前总下载长度 
 int crrrentTotalProgress = currentprogress + len; 
 pb.setProgress(crrrentTotalProgress); 
  
 //获取总大小 
 int maxProgress = pb.getMax(); 
 //计算百分比 
 float value = (float)currentprogress / (float)maxProgress; 
 int percent = (int) (value * 100); 
 //显示下载的百分比 
 tv_info.setText("下载:"+percent+"%"); 
  
 if(maxProgress == crrrentTotalProgress){ 
  //删除下载记录 
  downloadDao.delete(ed_path.getText().toString()); 
 } 
 break; 
 default: 
 break; 
 } 
 }; 
 }; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.activity_main); 
 this.ed_path = (EditText) super.findViewById(R.id.ed_path); 
 this.pb = (ProgressBar) super.findViewById(R.id.pb); 
 this.tv_info = (TextView) super.findViewById(R.id.tv_info); 
 this.manager = new DownloadManager(this); 
 this.downloadDao = new DownloadDao(this); 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
 // Inflate the menu; this adds items to the action bar if it is present. 
 getMenuInflater().inflate(R.menu.main, menu); 
 return true; 
 } 
 
 public void download(View v){ 
 final String path = ed_path.getText().toString(); 
 //下载 
 new Thread(new Runnable() { 
 @Override 
 public void run() { 
 // TODO Auto-generated method stub 
 try { 
  manager.download(path, new ProgressBarListener() { 
  @Override 
  public void getMax(int length) { 
  // TODO Auto-generated method stub 
  Message message = new Message(); 
  message.what = SET_PROGRESS_MAX; 
  message.obj = length; 
  mHandler.sendMessage(message); 
  } 
  
  @Override 
  public void getDownload(int length) { 
  // TODO Auto-generated method stub 
  Message message = new Message(); 
  message.what = UPDATE_PROGRESS; 
  message.obj = length; 
  mHandler.sendMessage(message); 
  } 
  }); 
 } catch (Exception e) { 
  // TODO: handle exception 
  e.printStackTrace(); 
  Message message = new Message(); 
  message.what = ERROR_DOWNLOAD; 
  mHandler.sendMessage(message); 
 } 
 } 
 }).start(); 
 } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
 package="com.example.multi" 
 android:versionCode="1" 
 android:versionName="1.0" > 
 
 <uses-sdk 
 android:minSdkVersion="8" 
 android:targetSdkVersion="18" /> 
 <uses-permission android:name="android.permission.INTERNET"/> 
 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> 
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> 
 <application 
 android:allowBackup="true" 
 android:icon="@drawable/ic_launcher" 
 android:label="@string/app_name" 
 android:theme="@style/AppTheme" > 
 <activity 
 android:name="com.example.multi.MainActivity" 
 android:label="@string/app_name" > 
 <intent-filter> 
 <action android:name="android.intent.action.MAIN" /> 
 
 <category android:name="android.intent.category.LAUNCHER" /> 
 </intent-filter> 
 </activity> 
 <provider android:name="com.example.provider.DownloadProvider" android:authorities="download"></provider> 
 </application> 
 
</manifest>