public void downLoad() throws Exception {currentProcess = 0;new Thread() {@Overridepublic void run() {URL url;try {url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setConnectTimeout(5000);conn.setRequestMethod("GET");int code = conn.getResponseCode();System.out.println("int code = conn.getResponseCode();---------->"+ code);if (code == 200) {// 服务器返回的数据的长度，实际上就是文件的长度int length = conn.getContentLength();System.out.println("文件总长度" + length);// 在客户端本地创建出来一个大小跟服务器端文件大小一样的临时文件
                        RandomAccessFile raf;raf = new RandomAccessFile("/data/data/com.yydcdut.duothread/lala.exe", "rwd");raf.setLength(length);raf.close();// 假设是3个线程去下载资源// 平均每一个线程下载的文件大小int blockSize = length / threadCount;for (int threadId = 1; threadId <= threadCount; threadId++) {// 第一个线程下载的开始位置int startIndex = (threadId - 1) * blockSize;int endIndex = threadId * blockSize;if (threadId == threadCount) {// 最后个线程下载的长度弄得稍微大一点endIndex = length;}System.out.println("线程：" + threadId + "---下载："+ startIndex + "--->" + endIndex);// 开始下载new DownloadThread(path, threadId, startIndex,endIndex).start();}} else {System.out.println("服务器错误!!!");Message msg = new Message();msg.what = SERVER_ERROR;handler.sendMessage(msg);}} catch (MalformedURLException e1) {// TODO 自动生成的 catch 块
                    e1.printStackTrace();} catch (Exception e) {// TODO 自动生成的 catch 块
                    e.printStackTrace();}super.run();}}.start();}

public class DownloadThread extends Thread {private int threadId;private int startIndex;private int endIndex;private String path;public DownloadThread(String path, int threadId, int startIndex,int endIndex) {super();this.threadId = threadId;this.startIndex = startIndex;this.endIndex = endIndex;this.path = path;}@Overridepublic void run() {File tempFile = new File("/data/data/com.yydcdut.duothread/" + threadId + ".txt");if (tempFile.exists() && tempFile.length() > 0) {try {FileInputStream fis = new FileInputStream(tempFile);byte[] temp = new byte[1024];int leng = fis.read(temp);String downLoadLen = new String(temp, 0, leng);int downloadlenInt = Integer.parseInt(downLoadLen);int alreadyDowlLoad = downloadlenInt - startIndex;currentProcess += alreadyDowlLoad;startIndex = downloadlenInt;// 修改下载的真实的开始位置
                    fis.close();} catch (Exception e) {// TODO 自动生成的 catch 块
                    e.printStackTrace();}}URL url;try {url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");conn.setConnectTimeout(5000);conn.setRequestProperty("Range", "bytes=" + startIndex + "-"+ endIndex);System.out.println("线程真实下载：" + threadId + "下载----" + startIndex+ "---->" + endIndex);int code = conn.getResponseCode();// 从服务器请求全部资源200 如果请求部分资源206System.out.println("threadId--->" + threadId + "----code:"+ code);InputStream is = conn.getInputStream();// 设置请求位置，返回是当前位置对应的文件输入流// 随机写文件的时候从那个位置开始写RandomAccessFile raf = new RandomAccessFile("/data/data/com.yydcdut.duothread/lala.exe","rwd");raf.seek(startIndex);int len = 0;byte[] buffer = new byte[1024];int total = 0;// 记录下载多少了while ((len = is.read(buffer)) != -1) {total += len;raf.write(buffer, 0, len);// System.out.println("线程："+threadId+"下载了total:"+total);RandomAccessFile file = new RandomAccessFile("/data/data/com.yydcdut.duothread/"+ threadId + ".txt", "rwd");file.write((total + startIndex + "").getBytes());file.close();// 更新进度条synchronized (MainActivity.this) {currentProcess += len;pb.setProgress(currentProcess);Message msg = new Message();msg.what = UPDATE_TEXT;handler.sendMessage(msg);}}is.close();raf.close();System.out.println("线程" + threadId + "下载完毕............");} catch (Exception e) {// TODO 自动生成的 catch 块
                e.printStackTrace();} finally {threadFinish();}super.run();}}

private synchronized void threadFinish() {runningThread--;if (runningThread == 0) {for (int i = 1; i <= 3; i++) {File file = new File("/data/data/com.yydcdut.duothread/" + i + ".txt");file.delete();}System.out.println("文件下载完毕，删除所有的下载记录。。。");Message msg = new Message();msg.what = DOWN_LOAD_FINISH;handler.sendMessage(msg);}}

private Handler handler = new Handler() {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case DOWN_LOAD_ERROR:Toast.makeText(getApplicationContext(), "下载失败", 0).show();break;case SERVER_ERROR:Toast.makeText(getApplicationContext(), "服务器 错误,下载失败", 0).show();break;case DOWN_LOAD_FINISH:Toast.makeText(getApplicationContext(), "文件下载完毕", 0).show();break;case UPDATE_TEXT:et_path.setText("当前进度:" + pb.getProgress() * 100 / pb.getMax());break;}super.handleMessage(msg);}};