Android应用开发与系统改造实战.王保卫等.源代码

package com.test.multithread; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; import android.util.Log; public class DownloadTask { private String mFileDir = null; //private String mCharSet = null; // 编码格式 private String mFileName = null; // 将要下载的文件的名称 private URL mURL = null; private int threadNumber = 5; private double contentLengthPerThread = 0.0; private ChildThread[] childThreads = new ChildThread[threadNumber]; private boolean mStatusError = false; private int mSleepSecondes = 0; private String LOGTAG = "download"; /** * 第一步是用来设置断点续传时候的一些信息的，第二步就是主要的分多线程来下载了，最后是数据的合并。 * * @param urlString * 将要下载的页面的url * @param charset * 将要下载的页面的编码方式 */ public void download(String urlString, String charset) { //mCharSet = charset;// 编码格式 long contentLength = 0;// 文件总大小 CountDownLatch latch = new CountDownLatch(threadNumber); long[] startPosition = new long[threadNumber]; long endPosition = 0; try { // 从url中获得下载的文件格式与名字 mFileName = urlString.substring(urlString.lastIndexOf("/") + 1); mFileDir = "/sdcard/"; mURL = new URL(urlString); URLConnection con = mURL.openConnection(); //setHeader(con); // 得到content的长度 contentLength = con.getContentLength(); // 把context分为threadNumber段的话，每段的长度。 contentLengthPerThread = contentLength / threadNumber; // 第一步，分析已下载的临时文件，设置断点，如果是新的下载任务，则建立目标文件。在第4点中说明。 startPosition = setThreadBreakpoint(mFileDir, mFileName, contentLength, startPosition); // 第二步，分多个线程下载文件 ExecutorService exec = Executors.newCachedThreadPool(); for (int i = 0; i < threadNumber; i++) { // 创建子线程来负责下载数据，每段数据的起始位置为(contentLengthPerThread * i + 已下载长度) //startPosition[i] += contentLengthPerThread * i;//错误，要去掉+号或者*号 startPosition[i] += contentLengthPerThread * i; // 设置子线程的终止位置，非最后一个线程即为(contentLengthPerThread * (i + 1) - 1) // 最后一个线程的终止位置即为下载内容的长度 if (i == threadNumber - 1) { endPosition = contentLength; } else { endPosition = (long) contentLengthPerThread * (i + 1) - 1; } // 开启子线程，并执行。 ChildThread thread = new ChildThread(this, latch, i, startPosition[i], endPosition); childThreads[i] = thread; exec.execute(thread); } // 等待CountdownLatch信号为0，表示所有子线程都结束。 latch.await(); exec.shutdown(); // 第三步，把分段下载下来的临时文件中的内容写入目标文件中。在第3点中说明。 tempFileToTargetFile(childThreads); } catch (Exception e) { e.printStackTrace(); } } public class ChildThread extends Thread { private static final int RECONNECT_MAX = 10; private static final int STATUS_HTTPSTATUS_ERROR = 0; private static final int STATUS_HAS_FINISHED = 1; private DownloadTask task; private int threadId; private long startPosition; private long endPosition; private final CountDownLatch latch; private File tempFile = null; private boolean hasFinished = false; private int status = STATUS_HAS_FINISHED; public ChildThread(DownloadTask task, CountDownLatch latch, int threadId, long startPosition, long endPosition) { super(); this.task = task; this.threadId = threadId; this.startPosition = startPosition; this.endPosition = endPosition; this.latch = latch; try { tempFile = new File(this.task.mFileDir + this.task.mFileName + "_" + threadId); if (!tempFile.exists()) { tempFile.createNewFile(); } } catch (IOException e) { e.printStackTrace(); } } public void run() { Log.d(LOGTAG,"Thread " + threadId + " run ..."); HttpURLConnection con = null; InputStream inputStream = null; BufferedOutputStream outputStream = null; long count = 0; long threadDownloadLength = endPosition - startPosition; try { outputStream = new BufferedOutputStream(new FileOutputStream(tempFile.getPath(), true)); } catch (FileNotFoundException e) { e.printStackTrace(); } for(int k = 0; k < RECONNECT_MAX; k++){ if(k > 0) Log.d("download","Now thread " + threadId + "is reconnect, start position is " + startPosition); try { //打开URLConnection con = (HttpURLConnection) task.mURL.openConnection(); // setHeader(con); con.setAllowUserInteraction(true); //设置连接超时时间为10000ms con.setConnectTimeout(10000); //设置读取数据超时时间为10000ms con.setReadTimeout(10000); if(startPosition < endPosition){ //设置下载数据的起止区间 con.setRequestProperty("Range", "bytes=" + startPosition + "-" + endPosition); Log.d(LOGTAG, "Thread " + threadId + " startPosition is " + startPosition); Log.d(LOGTAG, "Thread " + threadId + " endPosition is " + endPosition); // 判断http status是否为HTTP/1.1 206 Partial Content或者200 OK // 如果不是以上两种状态，把status改为STATUS_HTTPSTATUS_ERROR if (con.getResponseCode() != HttpURLConnection.HTTP_OK && con.getResponseCode() != HttpURLConnection.HTTP_PARTIAL) { Log.d(LOGTAG, "Thread " + threadId + ": code = " + con.getResponseCode() + ", status = " + con.getResponseMessage()); status = ChildThread.STATUS_HTTPSTATUS_ERROR; this.task.mStatusError = true; outputStream.close(); con.disconnect(); Log.d(LOGTAG, "Thread " + threadId + " finished."); latch.countDown(); break; } inputStream = con.getInputStream(); int len = 0; byte[] b = new byte[1024]; while ((len = inputStream.read(b)) != -1) { outputStream.write(b, 0, len); count += len; startPosition += count; //每读满4096个byte（一个内存页），往磁盘上flush一下 if(count % 4096 == 0){ outputStream.flush(); } } Log.d(LOGTAG, "count is " + count); if(count == threadDownloadLength){ hasFinished = true; } outputStream.flush(); outputStream.c