java多线程下载文件原理解析

import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

public class MutilDownload {
  private static String path = "http://192.168.80.85:8080/test.doc";
  private static final int threadCount = 3;

  public static void main(String[] args) {
    try {
      URL url = new URL(path);
      HttpURLConnection cOnn= (HttpURLConnection) url.openConnection();
      conn.setRequestMethod("GET");
      conn.setConnectTimeout(5000);
      int respOnseCode= conn.getResponseCode();
      if (respOnseCode== 200) {
        int cOntentLength= conn.getContentLength();
        System.out.println("length" + contentLength);

        RandomAccessFile rafAccessFile = new RandomAccessFile("test.doc", "rw");
        rafAccessFile.setLength(contentLength);

        int blockSize = contentLength / threadCount;
        for (int i = 0; i