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package com.itheima.multiThreadDownload;//import java.net.MalformedURLException;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.URL;//import java.net.URLConnection;public class MultiThreadDownload {     private static String path = "http://127.0.0.1:8080/FeiQ.exe";     private static int threadCount= 3;//不搞那么多就搞三个线程.     public static void main(String[] args) {        //①联网获取要下载的文件长度        try {            URL url = new URL(path);            //URLConnection openConnection = url.openConnection();            HttpURLConnection openConnection = (HttpURLConnection) url.openConnection();            openConnection.setRequestMethod("GET");            openConnection.setConnectTimeout(10000);            int responseCode = openConnection.getResponseCode();            if(responseCode==200){                //获取要下载的文件长度                //int contentLength = openConnection.getContentLength();                //long contentLengthLong = openConnection.getContentLengthLong();                int contentLength = openConnection.getContentLength();                //在本地创建一个一样的文件                RandomAccessFile file = new RandomAccessFile(getFilename(path), "rw");//第一个叫file或者说是name(路径),第二个参数叫mode                //名字可以通过路径去获取,截取这个路径最后一个斜杠.剩下的这个就是我要下载的文件名                //file.setLength(contentLengthLong);//文件创建出来之后去设置文件的长度                file.setLength(contentLength);//文件创建出来之后去设置文件的长度                //计算每一个线程要下载多少数据                //int blockSize = contentLengthLong/threadCount;                int blockSize = contentLength/threadCount;                //计算每一个线程要下载的数据范围                for (int i = 0; i < threadCount; i++) {                    //用i和blockSize来确定startIndex和endIndex                    int startIndex  = i*blockSize;                     int endIndex = (i+1)*blockSize-1;                    if(i==threadCount-1){                        //说明是最后一个线程                        endIndex = contentLength-1;                    }                }            }        } //catch (MalformedURLException e) {
          catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    private static String getFilename(String path) {        String[] split = path.split("/");//拿斜杠去切                return split[split.length-1];    }}

 

 

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接下来得创建多个线程，在多线程里面去创建不同的数据。