Java multithreaded download file instance details

Example of this article for you to share Java multithreaded download file specific code, for your reference, the specific content is as follows

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); 
  } 
 
  /** 
   *  The download file  
   * 
   * @param path 
   *       Network file path  
   * @param threadSize 
   *       The number of threads  
   * @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();//  Gets the network file length  
      File file = new File(getFileName(path)); 
      //  Generate locally 1 Three files of the same length as the network file  
      RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); 
      accessFile.setLength(length); 
      accessFile.close(); 
 
      //  Calculate the amount of data each thread is responsible for downloading  
      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; //  Where does the compute thread start downloading from the network file  
      int end = (threadId + 1) * block - 1; //  Calculate where the download to the network file ends  
      try { 
        RandomAccessFile accessFile = new RandomAccessFile(file, "rwd"); 
        accessFile.seek(start); // from start start  
 
        HttpURLConnection connection = (HttpURLConnection) url 
            .openConnection(); 
        connection.setRequestMethod("GET"); 
        connection.setConnectTimeout(5000); 
        // Set the scope to get resource data from start to end 
        connection.setRequestProperty("Range", "bytes=" + start + "-" 
            + end); 
        // Note that the multithreaded download status code is  206  not 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(" The first " + (threadId + 1) + " A thread has been downloaded "); 
      } catch (Exception e) { 
        e.printStackTrace(); 
      } 
    } 
  } 
 
  /** 
   *  Get file name  
   * 
   * @param path 
   *       Network file path  
   * @return 
   */ 
  private String getFileName(String path) { 
    return path.substring(path.lastIndexOf("/") + 1); 
  } 
}