本文實例為大家分享了Java多線程下載文件的具體代碼，供大家參考，具體內(nèi)容如下
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import java.io.File; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.URL; public class MulThreadDownload { public static void main(String[] args) throws Exception { String path = "http://192.168.1.100:8080/Hello/Big.exe"; new MulThreadDownload().download(path, 3); } /** * 下載文件 * * @param path * 網(wǎng)絡(luò)文件路徑 * @param threadSize * 線程數(shù) * @throws Exception */ private void download(String path, int threadSize) throws Exception { URL url = new URL(path); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(5000); if (connection.getResponseCode() == 200) { int length = connection.getContentLength();// 獲取網(wǎng)絡(luò)文件長度 File file = new File(getFileName(path)); // 在本地生成一個長度與網(wǎng)絡(luò)文件相同的文件 RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); accessFile.setLength(length); accessFile.close(); // 計算每條線程負(fù)責(zé)下載的數(shù)據(jù)量 int block = length % threadSize == 0 ? length / threadSize : length / threadSize + 1; for (int threadId = 0; threadId < threadSize; threadId++) { new DownloadThread(threadId, block, url, file).start(); } } else { System.out.println("download fail"); } } private class DownloadThread extends Thread { private int threadId; private int block; private URL url; private File file; public DownloadThread(int threadId, int block, URL url, File file) { this.threadId = threadId; this.block = block; this.url = url; this.file = file; } @Override public void run() { int start = threadId * block; // 計算該線程從網(wǎng)絡(luò)文件什么位置開始下載 int end = (threadId + 1) * block - 1; // 計算下載到網(wǎng)絡(luò)文件什么位置結(jié)束 try { RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); accessFile.seek(start); //從start開始 HttpURLConnection connection = (HttpURLConnection) url .openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(5000); //設(shè)置獲取資源數(shù)據(jù)的范圍，從start到end connection.setRequestProperty("Range", "bytes=" + start + "-" + end); //注意多線程下載狀態(tài)碼是 206 不是200 if (connection.getResponseCode() == 206) { InputStream inputStream = connection.getInputStream(); byte[] buffer = new byte[1024]; int len = 0; while ((len = inputStream.read(buffer)) != -1) { accessFile.write(buffer, 0, len); } accessFile.close(); inputStream.close(); } System.out.println("第" + (threadId + 1) + "條線程已經(jīng)下載完成"); } catch (Exception e) { e.printStackTrace(); } } } /** * 獲取文件名稱 * * @param path * 網(wǎng)絡(luò)文件路徑 * @return */ private String getFileName(String path) { return path.substring(path.lastIndexOf("/") + 1); } } |
以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持服務(wù)器之家。
