本文主要包含多線程下載的一些簡單demo,包括三部分

java實現

android實現

XUtils開源庫實現

注意下載添加網絡權限與SD卡讀寫權限

java實現多線程下載

public class MutileThreadDownload {/*** 線程的數量*/private static int threadCount = 3;/*** 每個下載區(qū)塊的大小*/private static long blocksize;/*** 正在運行的線程的數量*/private static int runningThreadCount;/*** @param args* @throws Exception*/public static void main(String[] args) throws Exception {// 服務器文件的路徑String path = "http://192.168.1.100:8080/ff.exe";URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");conn.setConnectTimeout(5000);int code = conn.getResponseCode();if (code == 200) {long size = conn.getContentLength();// 得到服務端返回的文件的大小System.out.println("服務器文件的大小：" + size);blocksize = size / threadCount;// 1.首先在本地創(chuàng)建一個大小跟服務器一模一樣的空白文件。File file = new File("temp.exe");RandomAccessFile raf = new RandomAccessFile(file, "rw");raf.setLength(size);// 2.開啟若干個子線程分別去下載對應的資源。runningThreadCount = threadCount;for (int i = 1; i <= threadCount; i++) {long startIndex = (i - 1) * blocksize;long endIndex = i * blocksize - 1;if (i == threadCount) {// 最后一個線程endIndex = size - 1;}System.out.println("開啟線程：" + i + "下載的位置：" + startIndex + "~"+ endIndex);new DownloadThread(path, i, startIndex, endIndex).start();}}conn.disconnect();}private static class DownloadThread extends Thread {private int threadId;private long startIndex;private long endIndex;private String path;public DownloadThread(String path, int threadId, long startIndex,long endIndex) {this.path = path;this.threadId = threadId;this.startIndex = startIndex;this.endIndex = endIndex;}@Overridepublic void run() {try {// 當前線程下載的總大小int total = 0;File positionFile = new File(threadId + ".txt");URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");// 接著從上一次的位置繼續(xù)下載數據if (positionFile.exists() && positionFile.length() > 0) {// 判斷是否有記錄FileInputStream fis = new FileInputStream(positionFile);BufferedReader br = new BufferedReader(new InputStreamReader(fis));// 獲取當前線程上次下載的總大小是多少String lasttotalstr = br.readLine();int lastTotal = Integer.valueOf(lasttotalstr);System.out.println("上次線程" + threadId + "下載的總大小："+ lastTotal);startIndex += lastTotal;total += lastTotal;// 加上上次下載的總大小。fis.close();}conn.setRequestProperty("Range", "bytes=" + startIndex + "-"+ endIndex);conn.setConnectTimeout(5000);int code = conn.getResponseCode();System.out.println("code=" + code);InputStream is = conn.getInputStream();File file = new File("temp.exe");RandomAccessFile raf = new RandomAccessFile(file, "rw");// 指定文件開始寫的位置。raf.seek(startIndex);System.out.println("第" + threadId + "個線程：寫文件的開始位置："+ String.valueOf(startIndex));int len = 0;byte[] buffer = new byte[512];while ((len = is.read(buffer)) != -1) {RandomAccessFile rf = new RandomAccessFile(positionFile,"rwd");raf.write(buffer, 0, len);total += len;rf.write(String.valueOf(total).getBytes());rf.close();}is.close();raf.close();} catch (Exception e) {e.printStackTrace();} finally {// 只有所有的線程都下載完畢后 才可以刪除記錄文件。synchronized (MutileThreadDownload.class) {System.out.println("線程" + threadId + "下載完畢了");runningThreadCount--;if (runningThreadCount < 1) {System.out.println("所有的線程都工作完畢了。刪除臨時記錄的文件");for (int i = 1; i <= threadCount; i++) {File f = new File(i + ".txt");System.out.println(f.delete());}}}}}} }

安卓實現

public class MainActivity extends Activity {protected static final int DOWNLOAD_ERROR = 1;private static final int THREAD_ERROR = 2;public static final int DWONLOAD_FINISH = 3;private EditText et_path;private EditText et_count;/*** 存放進度條的布局*/private LinearLayout ll_container;/*** 進度條的集合*/private List<ProgressBar> pbs;/*** android下的消息處理器，在主線程創(chuàng)建，才可以更新ui*/private Handler handler = new Handler(){public void handleMessage(Message msg) {switch (msg.what) {case DOWNLOAD_ERROR:Toast.makeText(getApplicationContext(), "下載失敗", 0).show();break;case THREAD_ERROR:Toast.makeText(getApplicationContext(), "下載失敗,請重試", 0).show();break;case DWONLOAD_FINISH:Toast.makeText(getApplicationContext(), "下載完成", 0).show();break;}};};/*** 線程的數量*/private int threadCount = 3;/*** 每個下載區(qū)塊的大小*/private long blocksize;/*** 正在運行的線程的數量*/private int runningThreadCount;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);et_path = (EditText) findViewById(R.id.et_path);et_count = (EditText) findViewById(R.id.et_count);ll_container = (LinearLayout) findViewById(R.id.ll_container);}/*** 下載按鈕的點擊事件* @param view*/public void downLoad(View view){//下載文件的路徑final String path = et_path.getText().toString().trim();if(TextUtils.isEmpty(path)){Toast.makeText(this, "對不起下載路徑不能為空", 0).show();return;}String count = et_count.getText().toString().trim();if(TextUtils.isEmpty(path)){Toast.makeText(this, "對不起,線程數量不能為空", 0).show();return;}threadCount = Integer.parseInt(count);//清空掉舊的進度條ll_container.removeAllViews();//在界面里面添加count個進度條pbs = new ArrayList<ProgressBar>();for(int j=0;j<threadCount;j++){ProgressBar pb = (ProgressBar) View.inflate(this, R.layout.pb, null);ll_container.addView(pb);pbs.add(pb);}Toast.makeText(this, "開始下載", 0).show();new Thread(){public void run() {try {URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");conn.setConnectTimeout(5000);int code = conn.getResponseCode();if (code == 200) {long size = conn.getContentLength();// 得到服務端返回的文件的大小System.out.println("服務器文件的大小：" + size);blocksize = size / threadCount;// 1.首先在本地創(chuàng)建一個大小跟服務器一模一樣的空白文件。File file = new File(Environment.getExternalStorageDirectory(),getFileName(path));RandomAccessFile raf = new RandomAccessFile(file, "rw");raf.setLength(size);// 2.開啟若干個子線程分別去下載對應的資源。runningThreadCount = threadCount;for (int i = 1; i <= threadCount; i++) {long startIndex = (i - 1) * blocksize;long endIndex = i * blocksize - 1;if (i == threadCount) {// 最后一個線程endIndex = size - 1;}System.out.println("開啟線程：" + i + "下載的位置：" + startIndex + "~"+ endIndex);int threadSize = (int) (endIndex - startIndex);pbs.get(i-1).setMax(threadSize);new DownloadThread(path, i, startIndex, endIndex).start();}}conn.disconnect();} catch (Exception e) {e.printStackTrace();Message msg = Message.obtain();msg.what = DOWNLOAD_ERROR;handler.sendMessage(msg);}};}.start();}private class DownloadThread extends Thread {private int threadId;private long startIndex;private long endIndex;private String path;public DownloadThread(String path, int threadId, long startIndex,long endIndex) {this.path = path;this.threadId = threadId;this.startIndex = startIndex;this.endIndex = endIndex;}@Overridepublic void run() {try {// 當前線程下載的總大小int total = 0;File positionFile = new File(Environment.getExternalStorageDirectory(),getFileName(path)+threadId + ".txt");URL url = new URL(path);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");// 接著從上一次的位置繼續(xù)下載數據if (positionFile.exists() && positionFile.length() > 0) {// 判斷是否有記錄FileInputStream fis = new FileInputStream(positionFile);BufferedReader br = new BufferedReader(new InputStreamReader(fis));// 獲取當前線程上次下載的總大小是多少String lasttotalstr = br.readLine();int lastTotal = Integer.valueOf(lasttotalstr);System.out.println("上次線程" + threadId + "下載的總大小："+ lastTotal);startIndex += lastTotal;total += lastTotal;// 加上上次下載的總大小。fis.close();//存數據庫。//_id path threadid total}conn.setRequestProperty("Range", "bytes=" + startIndex + "-"+ endIndex);conn.setConnectTimeout(5000);int code = conn.getResponseCode();System.out.println("code=" + code);InputStream is = conn.getInputStream();File file = new File(Environment.getExternalStorageDirectory(),getFileName(path));RandomAccessFile raf = new RandomAccessFile(file, "rw");// 指定文件開始寫的位置。raf.seek(startIndex);System.out.println("第" + threadId + "個線程：寫文件的開始位置："+ String.valueOf(startIndex));int len = 0;byte[] buffer = new byte[1024];while ((len = is.read(buffer)) != -1) {RandomAccessFile rf = new RandomAccessFile(positionFile,"rwd");raf.write(buffer, 0, len);total += len;rf.write(String.valueOf(total).getBytes());rf.close();pbs.get(threadId-1).setProgress(total);}is.close();raf.close();} catch (Exception e) {e.printStackTrace();Message msg = Message.obtain();msg.what = THREAD_ERROR;handler.sendMessage(msg);} finally {// 只有所有的線程都下載完畢后 才可以刪除記錄文件。synchronized (MainActivity.class) {System.out.println("線程" + threadId + "下載完畢了");runningThreadCount--;if (runningThreadCount < 1) {System.out.println("所有的線程都工作完畢了。刪除臨時記錄的文件");for (int i = 1; i <= threadCount; i++) {File f = new File(Environment.getExternalStorageDirectory(),getFileName(path)+ i + ".txt");System.out.println(f.delete());}Message msg = Message.obtain();msg.what = DWONLOAD_FINISH;handler.sendMessage(msg);}}}}}//http://192.168.1.100:8080/aa.exeprivate String getFileName(String path){int start = path.lastIndexOf("/")+1;return path.substring(start);}}

利用XUtils開源框架實現，需要XUtils的jar包

public class MainActivity extends Activity {private EditText et_path;private TextView tv_info;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);et_path = (EditText) findViewById(R.id.et_path);tv_info = (TextView) findViewById(R.id.tv_info);}public void download(View view){String path = et_path.getText().toString().trim();if(TextUtils.isEmpty(path)){Toast.makeText(this, "請輸入下載的路徑", 0).show();return;}else{HttpUtils http = new HttpUtils();HttpHandler handler = http.download(path,"/sdcard/xxx.zip",true, // 如果目標文件存在，接著未完成的部分繼續(xù)下載。服務器不支持RANGE時將從新下載。true, // 如果從請求返回信息中獲取到文件名，下載完成后自動重命名。new RequestCallBack<File>() {@Overridepublic void onStart() {tv_info.setText("conn...");}@Overridepublic void onLoading(long total, long current, boolean isUploading) {tv_info.setText(current + "/" + total);}@Overridepublic void onSuccess(ResponseInfo<File> responseInfo) {tv_info.setText("downloaded:" + responseInfo.result.getPath());}@Overridepublic void onFailure(HttpException error, String msg) {tv_info.setText(msg);}});}} }

完成

總結

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