android手机多线程断点续传下载器案例源码

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软件测试界面

功能介绍：输入下载地址后，点击下载，进度条显示下载的百分比，处于下载时下载按钮无法使用，未开始下载，停止按钮无法使用

完整代码分析：

1.界面创建：

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="fill_parent"
 4     android:layout_height="fill_parent"
 5     android:orientation="vertical" >
 6 
 7     <TextView
 8         android:layout_width="fill_parent"
 9         android:layout_height="wrap_content"
10         android:text="@string/path" />
11 
12     <EditText
13         android:id="@+id/path"
14         android:layout_width="fill_parent"
15         android:layout_height="wrap_content"
16         android:text="http://192.168.0.117/testxml/xunlei.exe" />
17 <LinearLayout 
18     android:layout_width="fill_parent"
19     android:layout_height="wrap_content"
20     android:orientation="horizontal" 
21     >
22     <!--下载按钮-->
23      <Button
24         android:id="@+id/downloadbutton"
25         android:layout_width="wrap_content"
26         android:layout_height="wrap_content"
27         android:text="@string/button" />
28      <!--停止按钮-->
29       <Button
30         android:id="@+id/stopbutton"
31         android:layout_width="wrap_content"
32         android:layout_height="wrap_content"
33         android:text="@string/stopbutton" 
34         android:enabled="false"/>
35       
36 </LinearLayout>
37 
38     <ProgressBar
39         android:id="@+id/progressBar"
40         style="?android:attr/progressBarStyleHorizontal"
41         android:layout_width="fill_parent"
42         android:layout_height="18dp" />
43 <!--进度条下面的百分比-->
44     <TextView
45         android:id="@+id/resultview"
46         android:layout_width="fill_parent"
47         android:layout_height="wrap_content"
48         android:gravity="center" />
49 
50 </LinearLayout>

main.xml

2.清单文件

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 3     package="caicai.cn.multhreaddownloader"
 4     android:versionCode="1"
 5     android:versionName="1.0" >
 6 
 7     <uses-sdk android:minSdkVersion="8" />  
 8     <uses-permission android:name="android.permission.INTERNET"/>
 9     <!--允许装备或解除可移除的存储仓库的文件系统 -->
10     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
11     <!--允许写入外存储设备即SDcard -->
12     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
13 
14     <application
15         android:icon="@drawable/ic_launcher"
16         android:label="@string/app_name" >
17         <activity
18             android:label="@string/app_name"
19             android:name=".Cai_multhreaddownloaderActivity" >
20             <intent-filter >
21                 <action android:name="android.intent.action.MAIN" />
22 
23                 <category android:name="android.intent.category.LAUNCHER" />
24             </intent-filter>
25         </activity>
26     </application>
27 
28 </manifest>

AndroidManifest.xml

3.界面操作

  1 package caicai.cn.multhreaddownloader;
  2 
  3 import java.io.File;
  4 
  5 import net.download.DownloadProgressListener;
  6 import net.download.FileDownloader;
  7 
  8 import android.app.Activity;
  9 import android.os.Bundle;
 10 import android.os.Environment;
 11 import android.os.Handler;
 12 import android.os.Message;
 13 import android.view.View;
 14 import android.widget.Button;
 15 import android.widget.EditText;
 16 import android.widget.ProgressBar;
 17 import android.widget.TextView;
 18 import android.widget.Toast;
 19 
 20 public class Cai_multhreaddownloaderActivity extends Activity {
 21     private EditText pathtext;
 22     private TextView resultview;
 23     private Button downloadbutton;
 24     private Button stopbutton;
 25     private ProgressBar progressBar;
 26     private Handler handler = new Uihandler();
 27 
 28     // handler用于往创建handler对象所在的线程所绑定的消息队列发送消息
 29 
 30     private final class Uihandler extends Handler {// 接收从子线程传来的值，注意只有主线程才能对UI控件进行控制与更新
 31         public void handleMessage(Message msg) {
 32             switch (msg.what) {
 33             case 1:
 34                 int size = msg.getData().getInt("size");
 35                 progressBar.setProgress(size);// 当前刻度;
 36                 float num = (float) progressBar.getProgress()
 37                         / (float) progressBar.getMax();
 38                 int result = (int) (num * 100);
 39                 resultview.setText(result + "%");
 40                 if (progressBar.getProgress() == progressBar.getMax()) {
 41                     Toast.makeText(getApplicationContext(), "下载完成", 1).show();
 42                 }
 43                 break;
 44             case -1:
 45                 Toast.makeText(getApplicationContext(), R.string.error, 1)
 46                         .show();
 47                 break;
 48             }
 49 
 50         }
 51     }
 52 
 53     public void onCreate(Bundle savedInstanceState) {
 54         super.onCreate(savedInstanceState);
 55         setContentView(R.layout.main);
 56         pathtext = (EditText) this.findViewById(R.id.path);
 57         resultview = (TextView) this.findViewById(R.id.resultview);
 58         downloadbutton = (Button) this.findViewById(R.id.downloadbutton);
 59         stopbutton = (Button) this.findViewById(R.id.stopbutton);
 60         progressBar = (ProgressBar) this.findViewById(R.id.progressBar);
 61         Buttonclicklistener listener = new Buttonclicklistener();
 62         downloadbutton.setOnClickListener(listener);
 63         stopbutton.setOnClickListener(listener);
 64     }
 65 
 66     private final class Buttonclicklistener implements View.OnClickListener {
 67 
 68         public void onClick(View v) {
 69             switch (v.getId()) {
 70             case R.id.downloadbutton:
 71                 String path = pathtext.getText().toString();// 获取下载路径
 72                 if (Environment.getExternalStorageState().equals(
 73                         Environment.MEDIA_MOUNTED)) {// 判断SDcard是否存在 或者可写数据
 74                     File savedir = Environment.getExternalStorageDirectory();// 获取sdcard跟目录，即保存路径
 75                     download(path, savedir);
 76                 }else{
 77                     Toast.makeText(getApplicationContext(),R.string.sdcarderror, 1).show();
 78                 }            
 79                 downloadbutton.setEnabled(false);
 80                 stopbutton.setEnabled(true);
 81                 break;
 82             case R.id.stopbutton:
 83                 exit();
 84                 downloadbutton.setEnabled(true);
 85                 stopbutton.setEnabled(false);
 86                 break;
 87             }
 88         }
 89 
 90         /*
 91          * 由于用户的输入事件(点击button, 触摸屏幕....)是由主线程负责处理的，如果主线程处于工作状态，
 92          * 此时用户产生的输入事件如果没能在5秒内得到处理，系统就会报“应用无响应”错误。
 93          * 所以在主线程里不能执行一件比较耗时的工作，否则会因主线程阻塞而无法处理用户的输入事件，
 94          * 导致“应用无响应”错误的出现。耗时的工作应该在子线程里执行。
 95          */
 96         private DownloadTask task;
 97         private void exit() {//退出下载
 98             if (task!= null) {
 99                 task.exit();
100             }
101         };
102 
103         private void download(String path, File savedir) {
104             task = new DownloadTask(path, savedir);
105             new Thread(task).start();
106         }
107 
108         private final class DownloadTask implements Runnable {
109             String path;
110             File savedir;
111             FileDownloader loader;
112 
113             public DownloadTask(String path, File savedir) {
114                 this.path = path;
115                 this.savedir = savedir;
116             }
117 
118             public void exit() {
119                 if (loader != null) {
120                     loader.exit();// 退出下载
121                 }
122             }
123 
124             @Override
125             public void run() {
126                 try {
127                     loader = new FileDownloader(getApplicationContext(), path,
128                             savedir, 3);
129                     progressBar.setMax(loader.getFileSize());// 设置进度条最大刻度
130                     loader.download(new DownloadProgressListener() {
131                         @Override
132                         public void onDownloadSize(int size) {
133                             Message msg = new Message();
134                             msg.what = 1;// 定义消息的ID，以便区别那个消息发过来的
135                             msg.getData().putInt("size", size);
136                             handler.sendMessage(msg);
137 
138                         }
139                     });
140                 } catch (Exception e) {
141                     e.printStackTrace();
142                     handler.sendMessage(handler.obtainMessage(-1));// 发送编号为-1的空消息
143                 }
144 
145             }
146 
147         }
148     }
149 }

Cai_multhreaddownloaderActivity.java

4.下载接口

1 package net.download;
2 
3 public interface DownloadProgressListener {
4     public void onDownloadSize(int size);
5 }

DownloadProgressListener.java

5.下载线程类

 1 package net.download;
 2 
 3 import java.io.File;
 4 import java.io.InputStream;
 5 import java.io.RandomAccessFile;
 6 import java.net.HttpURLConnection;
 7 import java.net.URL;
 8 
 9 import android.util.Log;
10 
11 public class DownloadThread extends Thread {
12     private static final String TAG = "DownloadThread";
13     private File saveFile;
14     private URL downUrl;
15     private int block;
16     /* 下载开始位置  */
17     private int threadId = -1;    
18     private int downLength;
19     private boolean finish = false;
20     private FileDownloader downloader;
21 
22     public DownloadThread(FileDownloader downloader, URL downUrl, File saveFile, int block, int downLength, int threadId) {
23         this.downUrl = downUrl;
24         this.saveFile = saveFile;
25         this.block = block;
26         this.downloader = downloader;
27         this.threadId = threadId;
28         this.downLength = downLength;
29     }
30     
31     @Override
32     public void run() {
33         if(downLength < block){//未下载完成
34             try {
35                 HttpURLConnection http = (HttpURLConnection) downUrl.openConnection();
36                 http.setConnectTimeout(5 * 1000);
37                 http.setRequestMethod("GET");
38                 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, */*");
39                 http.setRequestProperty("Accept-Language", "zh-CN");
40                 http.setRequestProperty("Referer", downUrl.toString()); 
41                 http.setRequestProperty("Charset", "UTF-8");
42                 int startPos = block * (threadId - 1) + downLength;//开始位置
43                 int endPos = block * threadId -1;//结束位置
44                 http.setRequestProperty("Range", "bytes=" + startPos + "-"+ endPos);//设置获取实体数据的范围
45                 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)");
46                 http.setRequestProperty("Connection", "Keep-Alive");
47                 
48                 InputStream inStream = http.getInputStream();
49                 byte[] buffer = new byte[1024];
50                 int offset = 0;
51                 print("Thread " + this.threadId + " start download from position "+ startPos);
52                 RandomAccessFile threadfile = new RandomAccessFile(this.saveFile, "rwd");
53                 threadfile.seek(startPos);
54                 while (!downloader.getExit() && (offset = inStream.read(buffer, 0, 1024)) != -1) {
55                     threadfile.write(buffer, 0, offset);
56                     downLength += offset;
57                     downloader.update(this.threadId, downLength);
58                     downloader.append(offset);
59                 }
60                 threadfile.close();
61                 inStream.close();
62                 print("Thread " + this.threadId + " download finish");
63                 this.finish = true;
64             } catch (Exception e) {
65                 this.downLength = -1;
66                 print("Thread "+ this.threadId+ ":"+ e);
67             }
68         }
69     }
70     private static void print(String msg){
71         Log.i(TAG, msg);
72     }
73     /**
74      * 下载是否完成
75      * @return
76      */
77     public boolean isFinish() {
78         return finish;
79     }
80     /**
81      * 已经下载的内容大小
82      * @return 如果返回值为-1,代表下载失败
83      */
84     public long getDownLength() {
85         return downLength;
86     }
87 }

DownloadThread.java

6.文件下载器

  1 package net.download;
  2 
  3 import java.io.File;
  4 import java.io.RandomAccessFile;
  5 import java.net.HttpURLConnection;
  6 import java.net.URL;
  7 import java.util.LinkedHashMap;
  8 import java.util.Map;
  9 import java.util.UUID;
 10 import java.util.concurrent.ConcurrentHashMap;
 11 import java.util.regex.Matcher;
 12 import java.util.regex.Pattern;
 13 import  service.FileService;
 14 
 15 import android.content.Context;
 16 import android.util.Log;
 17 /**
 18  * 文件下载器使用类案例
 19  * 
 20     try {
 21         FileDownloader loader = new FileDownloader(context, "http://browse.babasport.com/ejb3/ActivePort.exe",
 22                 new File("D:\\androidsoft\\test"), 2);
 23         loader.getFileSize();//得到文件总大小
 24         loader.download(new DownloadProgressListener(){
 25                 public void onDownloadSize(int size) {
 26                     print("已经下载："+ size);
 27                 }            
 28             });
 29     } catch (Exception e) {
 30             e.printStackTrace();
 31     }
 32  */
 33 public class FileDownloader {
 34     private static final String TAG = "FileDownloader";
 35     private Context context;
 36     private FileService fileService;
 37     /* 停止下载 */
 38     private boolean exit;
 39     /* 已下载文件长度 */
 40     private int downloadSize = 0;
 41     /* 原始文件长度 */
 42     private int fileSize = 0;
 43     /* 线程数 */
 44     private DownloadThread[] threads;
 45     /* 本地保存文件 */
 46     private File saveFile;
 47     /* 缓存各线程下载的长度*/
 48     private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();
 49     /* 每条线程下载的长度 */
 50     private int block;
 51     /* 下载路径  */
 52     private String downloadUrl;
 53     /**
 54      * 获取线程数
 55      */
 56     public int getThreadSize() {
 57         return threads.length;
 58     }
 59     /**
 60      * 退出下载
 61      */
 62     public void exit(){
 63         this.exit = true;
 64     }
 65     public boolean getExit(){
 66         return this.exit;
 67     }
 68     /**
 69      * 获取文件大小
 70      * @return
 71      */
 72     public int getFileSize() {
 73         return fileSize;
 74     }
 75     /**
 76      * 累计已下载大小
 77      * @param size
 78      */
 79     protected synchronized void append(int size) {
 80         downloadSize += size;
 81     }
 82     /**
 83      * 更新指定线程最后下载的位置
 84      * @param threadId 线程id
 85      * @param pos 最后下载的位置
 86      */
 87     protected synchronized void update(int threadId, int pos) {
 88         this.data.put(threadId, pos);
 89         this.fileService.update(this.downloadUrl, threadId, pos);
 90     }
 91     /**
 92      * 构建文件下载器
 93      * @param downloadUrl 下载路径
 94      * @param fileSaveDir 文件保存目录
 95      * @param threadNum 下载线程数
 96      */
 97     public FileDownloader(Context context, String downloadUrl, File fileSaveDir, int threadNum) {
 98         try {
 99             this.context = context;
100             this.downloadUrl = downloadUrl;
101             fileService = new FileService(this.context);
102             URL url = new URL(this.downloadUrl);
103             if(!fileSaveDir.exists()) fileSaveDir.mkdirs();
104             this.threads = new DownloadThread[threadNum];                    
105             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
106             conn.setConnectTimeout(5*1000);
107             conn.setRequestMethod("GET");
108             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, */*");
109             conn.setRequestProperty("Accept-Language", "zh-CN");
110             conn.setRequestProperty("Referer", downloadUrl); 
111             conn.setRequestProperty("Charset", "UTF-8");
112             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)");
113             conn.setRequestProperty("Connection", "Keep-Alive");
114             conn.connect();
115             printResponseHeader(conn);
116             if (conn.getResponseCode()==200) {
117                 this.fileSize = conn.getContentLength();//根据响应获取文件大小
118                 if (this.fileSize <= 0) throw new RuntimeException("Unkown file size ");
119                         
120                 String filename = getFileName(conn);//获取文件名称
121                 this.saveFile = new File(fileSaveDir, filename);//构建保存文件
122                 Map<Integer, Integer> logdata = fileService.getData(downloadUrl);//获取下载记录
123                 if(logdata.size()>0){//如果存在下载记录
124                     for(Map.Entry<Integer, Integer> entry : logdata.entrySet())
125                         data.put(entry.getKey(), entry.getValue());//把各条线程已经下载的数据长度放入data中
126                 }
127                 if(this.data.size()==this.threads.length){//下面计算所有线程已经下载的数据总长度
128                     for (int i = 0; i < this.threads.length; i++) {
129                         this.downloadSize += this.data.get(i+1);
130                     }
131                     print("已经下载的长度"+ this.downloadSize);
132                 }
133                 //计算每条线程下载的数据长度
134                 this.block = (this.fileSize % this.threads.length)==0? this.fileSize / this.threads.length : this.fileSize / this.threads.length + 1;
135             }else{
136                 throw new RuntimeException("server no response ");
137             }
138         } catch (Exception e) {
139             print(e.toString());
140             throw new RuntimeException("don't connection this url");
141         }
142     }
143     /**
144      * 获取文件名
145      */
146     private String getFileName(HttpURLConnection conn) {
147         String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1);
148         if(filename==null || "".equals(filename.trim())){//如果获取不到文件名称
149             for (int i = 0;; i++) {
150                 String mine = conn.getHeaderField(i);
151                 if (mine == null) break;
152                 if("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())){
153                     Matcher m = Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase());
154                     if(m.find()) return m.group(1);
155                 }
156             }
157             filename = UUID.randomUUID()+ ".tmp";//默认取一个文件名
158         }
159         return filename;
160     }
161     
162     /**
163      *  开始下载文件
164      * @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
165      * @return 已下载文件大小
166      * @throws Exception
167      */
168     public int download(DownloadProgressListener listener) throws Exception{
169         try {
170             RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw");
171             if(this.fileSize>0) randOut.setLength(this.fileSize);
172             randOut.close();
173             URL url = new URL(this.downloadUrl);
174             if(this.data.size() != this.threads.length){//如果原先未曾下载或者原先的下载线程数与现在的线程数不一致
175                 this.data.clear();
176                 for (int i = 0; i < this.threads.length; i++) {
177                     this.data.put(i+1, 0);//初始化每条线程已经下载的数据长度为0
178                 }
179                 this.downloadSize = 0;
180             }
181             for (int i = 0; i < this.threads.length; i++) {//开启线程进行下载
182                 int downLength = this.data.get(i+1);
183                 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    
184                     this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1);
185                     this.threads[i].setPriority(7);
186                     this.threads[i].start();
187                 }else{
188                     this.threads[i] = null;
189                 }
190             }
191             fileService.delete(this.downloadUrl);//如果存在下载记录，删除它们，然后重新添加
192             fileService.save(this.downloadUrl, this.data);
193             boolean notFinish = true;//下载未完成
194             while (notFinish) {// 循环判断所有线程是否完成下载
195                 Thread.sleep(900);
196                 notFinish = false;//假定全部线程下载完成
197                 for (int i = 0; i < this.threads.length; i++){
198                     if (this.threads[i] != null && !this.threads[i].isFinish()) {//如果发现线程未完成下载
199                         notFinish = true;//设置标志为下载没有完成
200                         if(this.threads[i].getDownLength() == -1){//如果下载失败,再重新下载
201                             this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1);
202                             this.threads[i].setPriority(7);
203                             this.threads[i].start();
204                         }
205                     }
206                 }                
207                 if(listener!=null) listener.onDownloadSize(this.downloadSize);//通知目前已经下载完成的数据长度
208             }
209             if(downloadSize == this.fileSize) fileService.delete(this.downloadUrl);//下载完成删除记录
210         } catch (Exception e) {
211             print(e.toString());
212             throw new Exception("file download error");
213         }
214         return this.downloadSize;
215     }
216     /**
217      * 获取Http响应头字段
218      * @param http
219      * @return
220      */
221     public static Map<String, String> getHttpResponseHeader(HttpURLConnection http) {
222         Map<String, String> header = new LinkedHashMap<String, String>();
223         for (int i = 0;; i++) {
224             String mine = http.getHeaderField(i);
225             if (mine == null) break;
226             header.put(http.getHeaderFieldKey(i), mine);
227         }
228         return header;
229     }
230     /**
231      * 打印Http头字段
232      * @param http
233      */
234     public static void printResponseHeader(HttpURLConnection http){
235         Map<String, String> header = getHttpResponseHeader(http);
236         for(Map.Entry<String, String> entry : header.entrySet()){
237             String key = entry.getKey()!=null ? entry.getKey()+ ":" : "";
238             print(key+ entry.getValue());
239         }
240     }
241 
242     private static void print(String msg){
243         Log.i(TAG, msg);
244     }
245 }

FileDownloader.java

7.数据库操作类

 1 package service;
 2 
 3 import android.content.Context;
 4 import android.database.sqlite.SQLiteDatabase;
 5 import android.database.sqlite.SQLiteOpenHelper;
 6 
 7 public class DBOpenHelper extends SQLiteOpenHelper {
 8     private static final String DBNAME = "download.db";
 9     private static final int VERSION = 1;
10     
11     public DBOpenHelper(Context context) {
12         super(context, DBNAME, null, VERSION);
13     }
14     
15     @Override
16     public void onCreate(SQLiteDatabase db) {
17         db.execSQL("CREATE TABLE IF NOT EXISTS filedownlog (id integer primary key autoincrement, downpath varchar(100), threadid INTEGER, downlength INTEGER)");
18     }
19 
20     @Override
21     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
22         db.execSQL("DROP TABLE IF EXISTS filedownlog");
23         onCreate(db);
24     }
25 
26 }

DBOpenHelper.java

8.下载的进度存入数据库操作类

 1 package service;
 2 
 3 import java.util.HashMap;
 4 import java.util.Map;
 5 
 6 import android.content.Context;
 7 import android.database.Cursor;
 8 import android.database.sqlite.SQLiteDatabase;
 9 /**
10  * 业务bean
11  *
12  */
13 public class FileService {
14     private DBOpenHelper openHelper;
15 
16     public FileService(Context context) {
17         openHelper = new DBOpenHelper(context);
18     }
19     /**
20      * 获取每条线程已经下载的文件长度
21      * @param path
22      * @return
23      */
24     public Map<Integer, Integer> getData(String path){
25         SQLiteDatabase db = openHelper.getReadableDatabase();
26         Cursor cursor = db.rawQuery("select threadid, downlength from filedownlog where downpath=?", new String[]{path});
27         Map<Integer, Integer> data = new HashMap<Integer, Integer>();
28         while(cursor.moveToNext()){
29             data.put(cursor.getInt(0), cursor.getInt(1));
30         }
31         cursor.close();
32         db.close();
33         return data;
34     }
35     /**
36      * 保存每条线程已经下载的文件长度
37      * @param path
38      * @param map
39      */
40     public void save(String path,  Map<Integer, Integer> map){//int threadid, int position
41         SQLiteDatabase db = openHelper.getWritableDatabase();
42         db.beginTransaction();
43         try{
44             for(Map.Entry<Integer, Integer> entry : map.entrySet()){
45                 db.execSQL("insert into filedownlog(downpath, threadid, downlength) values(?,?,?)",
46                         new Object[]{path, entry.getKey(), entry.getValue()});
47             }
48             db.setTransactionSuccessful();
49         }finally{
50             db.endTransaction();
51         }
52         db.close();
53     }
54     /**
55      * 实时更新每条线程已经下载的文件长度
56      * @param path
57      * @param map
58      */
59     public void update(String path, int threadId, int pos){
60         SQLiteDatabase db = openHelper.getWritableDatabase();
61         db.execSQL("update filedownlog set downlength=? where downpath=? and threadid=?",
62                 new Object[]{pos, path, threadId});
63         db.close();
64     }
65     /**
66      * 当文件下载完成后，删除对应的下载记录
67      * @param path
68      */
69     public void delete(String path){
70         SQLiteDatabase db = openHelper.getWritableDatabase();
71         db.execSQL("delete from filedownlog where downpath=?", new Object[]{path});
72         db.close();
73     }
74     
75 }