让我们看一下代码的实现方法。
复制
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; /** * 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 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 SmartFileDownlog(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 SmartFileDownlog 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 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; /** * 文件下载器 * @author lihuoming@sohu.com */ public class SmartFileDownloader { private static final String TAG = "SmartFileDownloader"; 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 SmartDownloadThread[] 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 void update(int threadId, int pos) { this.data.put(threadId, pos); } /** * 保存记录文件 */ protected synchronized void saveLogFile() { 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 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();//根据响应获取文件大小 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("已经下载的长度"+ this.downloadSize); } }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(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();//清除数据 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){ //该线程未完成下载时,继续下载 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;//下载未完成 while (notFinish) {// 循环判断是否下载完毕 Thread.sleep(900); notFinish = false;//假定下载完成 for (int i = 0; i < this.threads.length; i++){ if (this.threads != null && !this.threads.isFinish()) { notFinish = true;//下载没有完成 if(this.threads.getDownLength() == -1){//如果下载失败,再重新下载 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; } /** * 获取Http响应头字段 * @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头字段 * @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; /* *下载开始位置 */ 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.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; } } 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();//文件保存目录 download(path, dir); }else{ Toast.makeText(SmartDownloadActivity.this, R.string.sdcarderror, 1).show(); } } }); } //对于UI控件的更新只能由主线程(UI线程)负责，如果在非UI线程更新UI控件，更新的结果不会反映在屏幕上，某些控件还会出错 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();//获取文件的长度 downloadbar.setMax(length); loader.download(new SmartDownloadProgressListener(){ @Override public void onDownloadSize(int size) {//可以实时得到文件下载的长度 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", "下载失败");//如果下载错误，显示提示失败！ handler.sendMessage(msg); } } }).start();//开始 } }
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