Android中怎么實現(xiàn)多任務(wù)多線程斷點下載功能
Android 中怎么實現(xiàn)多任務(wù)多線程斷點下載功能，很多新手對此不是很清楚，為了幫助大家解決這個難題，下面小編將為大家詳細講解，有這方面需求的人可以來學(xué)習(xí)下，希望你能有所收獲。
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package com.smart.db; import java.util.HashMap; import java.util.Map; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; /** * 業(yè)務(wù)bean * */ public class FileService { private DBOpenHelper openHelper; public FileService(Context context) { openHelper = new DBOpenHelper(context); } /** * 獲取每條線程已經(jīng)下載的文件長度 * @param path * @return */ public Map<Integer, Integer> getData(String path){ SQLiteDatabase db = openHelper.getReadableDatabase(); Cursor cursor = db.rawQuery("select threadid, downlength from SmartFileDownlog 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; } /** * 保存每條線程已經(jīng)下載的文件長度 * @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 SmartFileDownlog(downpath, threadid, downlength) values(?,?,?)", new Object[]{path, entry.getKey(), entry.getValue()}); } db.setTransactionSuccessful(); }finally{ db.endTransaction(); } db.close(); } /** * 實時更新每條線程已經(jīng)下載的文件長度 * @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 SmartFileDownlog set downlength=? where downpath=? and threadid=?", new Object[]{entry.getValue(), path, entry.getKey()}); } db.setTransactionSuccessful(); }finally{ db.endTransaction(); } db.close(); } /** * 當(dāng)文件下載完成后，刪除對應(yīng)的下載記錄 * @param path */ public void delete(String path){ SQLiteDatabase db = openHelper.getWritableDatabase(); db.execSQL("delete from SmartFileDownlog where downpath=?", new Object[]{path}); db.close(); } } package com.smart.impl; 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 android.content.Context; import android.util.Log; import com.smart.db.FileService; /** * 文件下載器 * @author lihuoming@sohu.com */ public class SmartFileDownloader { private static final String TAG = "SmartFileDownloader"; private Context context; private FileService fileService; /* 已下載文件長度 */ private int downloadSize = 0; /* 原始文件長度 */ private int fileSize = 0; /* 線程數(shù) */ private SmartDownloadThread[] threads; /* 本地保存文件 */ private File saveFile; /* 緩存各線程下載的長度*/ private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>(); /* 每條線程下載的長度 */ private int block; /* 下載路徑 */ private String downloadUrl; /** * 獲取線程數(shù) */ public int getThreadSize() { return threads.length; } /** * 獲取文件大小 * @return */ public int getFileSize() { return fileSize; } /** * 累計已下載大小 * @param size */ protected synchronized void append(int size) { downloadSize += size; } /** * 更新指定線程最后下載的位置 * @param threadId 線程id * @param pos 最后下載的位置 */ protected void update(int threadId, int pos) { this.data.put(threadId, pos); } /** * 保存記錄文件 */ protected synchronized void saveLogFile() { this.fileService.update(this.downloadUrl, this.data); } /** * 構(gòu)建文件下載器 * @param downloadUrl 下載路徑 * @param fileSaveDir 文件保存目錄 * @param threadNum 下載線程數(shù) */ public SmartFileDownloader(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 SmartDownloadThread[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();//根據(jù)響應(yīng)獲取文件大小 if (this.fileSize <= 0) throw new RuntimeException("Unkown file size "); String filename = getFileName(conn); this.saveFile = new File(fileSaveDir, filename);/* 保存文件 */ Map<Integer, Integer> logdata = fileService.getData(downloadUrl); if(logdata.size()>0){ for(Map.Entry<Integer, Integer> entry : logdata.entrySet()) data.put(entry.getKey(), entry.getValue()); } this.block = (this.fileSize % this.threads.length)==0? this.fileSize / this.threads.length : this.fileSize / this.threads.length + 1; if(this.data.size()==this.threads.length){ for (int i = 0; i < this.threads.length; i++) { this.downloadSize += this.data.get(i+1); } print("已經(jīng)下載的長度"+ this.downloadSize); } }else{ throw new RuntimeException("server no response "); } } catch (Exception e) { print(e.toString()); throw new RuntimeException("don't connection this url"); } } /** * 獲取文件名 */ private String getFileName(HttpURLConnection conn) { String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1); if(filename==null || "".equals(filename.trim())){//如果獲取不到文件名稱 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";//默認取一個文件名 } return filename; } /** * 開始下載文件 * @param listener 監(jiān)聽下載數(shù)量的變化,如果不需要了解實時下載的數(shù)量,可以設(shè)置為null * @return 已下載文件大小 * @throws Exception */ public int download(SmartDownloadProgressListener 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();//清除數(shù)據(jù) for (int i = 0; i < this.threads.length; i++) { this.data.put(i+1, 0); } } for (int i = 0; i < this.threads.length; i++) { int downLength = this.data.get(i+1); if(downLength < this.block && this.downloadSize<this.fileSize){ //該線程未完成下載時,繼續(xù)下載 this.threads = new SmartDownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1); this.threads.setPriority(7); this.threads.start(); }else{ this.threads = null; } } this.fileService.save(this.downloadUrl, this.data); boolean notFinish = true;//下載未完成 while (notFinish) {// 循環(huán)判斷是否下載完畢 Thread.sleep(900); notFinish = false;//假定下載完成 for (int i = 0; i < this.threads.length; i++){ if (this.threads != null && !this.threads.isFinish()) { notFinish = true;//下載沒有完成 if(this.threads.getDownLength() == -1){//如果下載失敗,再重新下載 this.threads = new SmartDownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1); this.threads.setPriority(7); this.threads.start(); } } } if(listener!=null) listener.onDownloadSize(this.downloadSize); } fileService.delete(this.downloadUrl); } catch (Exception e) { print(e.toString()); throw new Exception("file download fail"); } return this.downloadSize; } /** * 獲取Http響應(yīng)頭字段 * @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頭字段 * @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()); } } //打印日志 private static void print(String msg){ Log.i(TAG, msg); } } package com.smart.impl; 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 SmartDownloadThread extends Thread { private static final String TAG = "SmartDownloadThread"; private File saveFile; private URL downUrl; private int block; /* *下載開始位置 */ private int threadId = -1; private int downLength; private boolean finish = false; private SmartFileDownloader downloader; public SmartDownloadThread(SmartFileDownloader 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){//未下載完成 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;//開始位置 int endPos = block * threadId -1;//結(jié)束位置 http.setRequestProperty("Range", "bytes=" + startPos + "-"+ endPos);//設(shè)置獲取實體數(shù)據(jù)的范圍 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.saveLogFile(); 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); } /** * 下載是否完成 * @return */ public boolean isFinish() { return finish; } /** * 已經(jīng)下載的內(nèi)容大小 * @return 如果返回值為-1,代表下載失敗 */ public long getDownLength() { return downLength; } } package com.smart.activoty.download; import java.io.File; 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; import com.smart.impl.SmartDownloadProgressListener; import com.smart.impl.SmartFileDownloader; public class SmartDownloadActivity extends Activity { private ProgressBar downloadbar; private EditText pathText; private TextView resultView; private Handler handler = new Handler(){ @Override//信息 public void handleMessage(Message msg) { switch (msg.what) { case 1: int size = msg.getData().getInt("size"); downloadbar.setProgress(size); float result = (float)downloadbar.getProgress()/ (float)downloadbar.getMax(); int p = (int)(result*100); resultView.setText(p+"%"); if(downloadbar.getProgress()==downloadbar.getMax()) Toast.makeText(SmartDownloadActivity.this, R.string.success, 1).show(); break; case -1: Toast.makeText(SmartDownloadActivity.this, R.string.error, 1).show(); break; } } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button)this.findViewById(R.id.button); downloadbar = (ProgressBar)this.findViewById(R.id.downloadbar); pathText = (EditText)this.findViewById(R.id.path); resultView = (TextView)this.findViewById(R.id.result); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String path = pathText.getText().toString(); if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ File dir = Environment.getExternalStorageDirectory();//文件保存目錄 download(path, dir); }else{ Toast.makeText(SmartDownloadActivity.this, R.string.sdcarderror, 1).show(); } } }); } //對于UI控件的更新只能由主線程(UI線程)負責(zé)，如果在非UI線程更新UI控件，更新的結(jié)果不會反映在屏幕上，某些控件還會出錯 private void download(final String path, final File dir){ new Thread(new Runnable() { @Override public void run() { try { SmartFileDownloader loader = new SmartFileDownloader(SmartDownloadActivity.this, path, dir, 3); int length = loader.getFileSize();//獲取文件的長度 downloadbar.setMax(length); loader.download(new SmartDownloadProgressListener(){ @Override public void onDownloadSize(int size) {//可以實時得到文件下載的長度 Message msg = new Message(); msg.what = 1; msg.getData().putInt("size", size); handler.sendMessage(msg); }}); } catch (Exception e) { Message msg = new Message();//信息提示 msg.what = -1; msg.getData().putString("error", "下載失敗");//如果下載錯誤，顯示提示失??！ handler.sendMessage(msg); } } }).start();//開始 } }看完上述內(nèi)容是否對您有幫助呢？如果還想對相關(guān)知識有進一步的了解或閱讀更多相關(guān)文章，請關(guān)注創(chuàng)新互聯(lián)行業(yè)資訊頻道，感謝您對創(chuàng)新互聯(lián)的支持。
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