多线程下载实例测试

package com.gyarmy.testDownload;

import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class ThreadDownload {
	
	private static int ThreadCount=5;
	private static String  path = "http://www.xxxx.com/file.txt";
	
	public static void main(String[] args) {
		
		try {
			URL url = new URL(path);
			HttpURLConnection conn = (HttpURLConnection)url.openConnection();
			conn.setConnectTimeout(20000);
			conn.setRequestMethod("GET");
			
			int code = conn.getResponseCode();
			if(200 == code){
				int contentLength = conn.getContentLength();
				System.out.println("长度:" + contentLength);
				
				//创建文件
				File file = new File(getFileName(path));
				
				RandomAccessFile raf = new RandomAccessFile(file, "rw");
				raf.setLength(contentLength);
				
				raf.close();
				
				int blockSize = contentLength/ThreadCount;
				
				for(int ThreadId=0;ThreadId<ThreadCount;ThreadId++){
					int startIndex = ThreadId*blockSize;
					int endIndex = (ThreadId+1)*blockSize-1;
					if(ThreadId==ThreadCount-1){
						endIndex = contentLength-1;
					}
					
					//System.out.println("线程ID:"+ThreadId+" 下载从 "+startIndex+" 开始, 结束的位置: "+endIndex);
					new MyThreadDownload(ThreadId,startIndex,endIndex).start();
				}
			}
		}catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	
	private static class  MyThreadDownload extends Thread{
		private int ThreadId;
		private int startIndex;
		private int endIndex;
		
		public MyThreadDownload(int ThreadId,int startIndex,int endIndex){
			this.ThreadId = ThreadId;
			this.startIndex = startIndex;
			this.endIndex = endIndex;
		}
		
		@Override
		public void run() {
			// TODO Auto-generated method stub
			super.run();
			System.out.println("线程ID:"+ThreadId+" 开始下载从 "+startIndex+" 开始, 结束的位置: "+endIndex);
			try {
				URL url = new URL(path);
				HttpURLConnection conn = (HttpURLConnection)url.openConnection();
				conn.setConnectTimeout(2000);
				conn.setRequestMethod("GET");
				conn.setRequestProperty("range", "bytes="+startIndex+"-"+endIndex);
				int code = conn.getResponseCode();
				
				if(206 == code){
					InputStream in = conn.getInputStream();
					File file = new File(getFileName(path));
					RandomAccessFile raf = new RandomAccessFile(file, "rw");
					
					raf.seek(startIndex);
					
					int len=0;
					byte[] buffer = new byte[1024];
					while((len = in.read(buffer))>0){
						raf.write(buffer, 0, len);
					}
					
					in.close();
					raf.close();
					
					
				}
				
				System.out.println("线程ID:"+ThreadId+" 下载完毕");
				
				
				
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		
	}
	
	
	
	
	public static String getFileName(String path)
	{
		int index = path.lastIndexOf("/");
		
		return path.substring(index+1);
	}
	
}