java 多线程下载
Posted Love丶陳
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了java 多线程下载相关的知识,希望对你有一定的参考价值。
package downLoad; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.URL; public class ThreadDownLoader extends Thread { private String path; private int startIndex; private int endIndex; private int threadId; private int threadCount; // 正在运行的线程个数 private static int runningThreadCount = 3; ThreadDownLoader(String path, int startIndex, int endIndex, int threadId, int threadCount) { this.path = path; this.startIndex = startIndex; this.endIndex = endIndex; this.threadId = threadId; this.threadCount = threadCount; } @Override public void run() { downLoad(path, startIndex, endIndex, threadId, threadCount); } public void downLoad(String path, int startIndex, int endIndex, int threadId, int threadCount) { try { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(3000); // 设置子线程请求数据的范围 conn.setRequestProperty("Range", "bytes=" + startIndex + "-" + endIndex); int code = conn.getResponseCode(); if (code == 206) {// 请求部分数据 InputStream is = conn.getInputStream(); RandomAccessFile file = new RandomAccessFile("temp.exe", "rw"); // 指定从哪个位置开始写数据 file.seek(startIndex); byte[] buffer = new byte[1024]; int len = -1; while ((len = is.read(buffer)) != -1) { file.write(buffer, 0, len); } file.close(); System.out.println("线程" + threadId + "下载完成..............."); synchronized (ThreadDownLoader.this) { runningThreadCount--; if (runningThreadCount == 0) { System.out.println("文件下载完成..............."); } } } } catch (Exception e) { System.out.println("线程" + threadId + "下载失败..............."); e.printStackTrace(); } } }
package downLoad; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.URL; public class MultiThreadDownLoader { // 2、使用的子线程的个数 private static int threadCount = 3; /** * @param args */ public static void main(String[] args) { try { String path = "https://download.jetbrains.8686c.com/idea/ideaIU-2018.3.1.exe";//文件路径 URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(3000); int code = conn.getResponseCode(); if (code == 200) { int length = conn.getContentLength(); // 1、在客户端创建一个与服务端文件一样大小的文件 RandomAccessFile file = new RandomAccessFile("temp.exe", "rw"); file.setLength(length); // 3、每个子线程下载数据块 ,下载的起始位置和结束位置 int blockSize = length / threadCount; // threadId * blockSize ---- (threadId+1)* blockSize -1 for (int threadId = 0; threadId < threadCount; threadId++) { // 下载的起始位置和结束位置 int startIndex = threadId * blockSize; int endIndex = 0; if (threadId != (threadCount - 1)) { endIndex = (threadId + 1) * blockSize - 1; } else { endIndex = length - 1; } // 开启子线程下载数据 new ThreadDownLoader(path, startIndex, endIndex, threadId, threadCount).start(); } } else { // 抛出异常 } } catch (Exception e) { e.printStackTrace(); } } }
以上是关于java 多线程下载的主要内容,如果未能解决你的问题,请参考以下文章