Android通过HTTP协议实现断点续传下载实例

 package cn.itcast.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 cn.itcast.service.FileService; import android.content.Context; import android.util.Log; /** * 文件下载器 * FileDownloader loader = new FileDownloader(context, "http://browse.babasport.com/ejb3/ActivePort.exe", new File("D:\\androidsoft\\test"), 2); loader.getFileSize();//得到文件总大小 try { loader.download(new DownloadProgressListener(){ public void onDownloadSize(int size) { print("已经下载："+ size); } }); } catch (Exception e) { e.printStackTrace(); } */ 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 data = new ConcurrentHashMap(); /* 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 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 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 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  getHttpResponseHeader(HttpURLConnection http) { Map header = new LinkedHashMap(); 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 header = getHttpResponseHeader(http); for(Map.Entry entry : header.entrySet()){ String key = entry.getKey()!=null ? entry.getKey()+ ":" : ""; print(key+ entry.getValue()); } } private static void print(String msg){ Log.i(TAG, msg); } } 

 package cn.itcast.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 

 package cn.itcast.net.download; public interface DownloadProgressListener { public void onDownloadSize(int size); } 

 package cn.itcast.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 = "itcast.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); } } 

 package cn.itcast.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 getData(String path){ SQLiteDatabase db = openHelper.getReadableDatabase(); Cursor cursor = db.rawQuery("select threadid, downlength from filedownlog where downpath=?", new String[]{path}); Map data = new HashMap(); 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 map){//int threadid, int position SQLiteDatabase db = openHelper.getWritableDatabase(); db.beginTransaction(); try{ for(Map.Entry 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 map){ SQLiteDatabase db = openHelper.getWritableDatabase(); db.beginTransaction(); try{ for(Map.Entry 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(); } } 

 package cn.itcast.download; import java.io.File; import cn.itcast.net.download.DownloadProgressListener; import cn.itcast.net.download.FileDownloader; 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.EditText; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; public class DownloadActivity extends Activity { private EditText downloadpathText; private TextView resultView; private ProgressBar progressBar; //当Handler被创建会关联到创建它的当前线程的消息队列，该类用于往消息队列发送消息 //消息队列中的消息由当前线程内部进行处理 private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { switch (msg.what) { case 1: progressBar.setProgress(msg.getData().getInt("size")); float num = (float)progressBar.getProgress()/(float)progressBar.getMax(); int result = (int)(num*100); resultView.setText(result+ "%"); if(progressBar.getProgress()==progressBar.getMax()){ Toast.makeText(DownloadActivity.this, R.string.success, 1).show(); } break; case -1: Toast.makeText(DownloadActivity.this, R.string.error, 1).show(); break; } } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); downloadpathText = (EditText) this.findViewById(R.id.downloadpath); progressBar = (ProgressBar) this.findViewById(R.id.downloadbar); resultView = (TextView) this.findViewById(R.id.result); Button button = (Button) this.findViewById(R.id.button); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String path = downloadpathText.getText().toString(); if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ download(path, Environment.getExternalStorageDirectory()); }else{ Toast.makeText(DownloadActivity.this, R.string.sdcarderror, 1).show(); } } }); } //主线程(UI线程) //业务逻辑正确，但是该程序运行的时候有问题 //对于显示控件的界面更新只是由UI线程负责，如果是在非UI线程更新控件的属性值，更新后的显示界面不会反映到屏幕上 private void download(final String path, final File savedir) { new Thread(new Runnable() { @Override public void run() { FileDownloader loader = new FileDownloader(DownloadActivity.this, path, savedir, 3); progressBar.setMax(loader.getFileSize());//设置进度条的最大刻度为文件的长度 try { loader.download(new DownloadProgressListener() { @Override public void onDownloadSize(int size) {//实时获知文件已经下载的数据长度 Message msg = new Message(); msg.what = 1; msg.getData().putInt("size", size); handler.sendMessage(msg);//发送消息 } }); } catch (Exception e) { handler.obtainMessage(-1).sendToTarget(); } } }).start(); } }