創建線程下載文件並創建計數器java

Question

我試圖製作一個下載文件的程序。在下載文件時，需要有一個基本的計數器，從頭到尾進行計數。這兩個功能需要在他們自己的線程中。我創建了一個方法/線程來下載文件。我很難弄清楚如何製作一個基本的計數器。沒有什麼奇特的，但它需要計數，只顯示當前的數字。任何幫助，將不勝感激。

import java.awt.Dimension; 
import java.awt.Toolkit; 
import java.io.BufferedInputStream; 
import java.io.ByteArrayOutputStream; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.zip.ZipEntry; 
import java.util.zip.ZipOutputStream; 
import static myutilites.methods.*; 


public class Downloader 
{ 

public static void main(String[] args) throws IOException 
{ 
    String filename = "Nexus5MahdiRom.zip"; 
    URL link = new URL(
    "http://files.mahdi-rom.com/OnePlus%20One/" 
    + "OnePlus%20One%20Builds/mahdi-2.7-bacon-20140903.zip"); 

    Thread t1 = new Thread(new Runnable() 
    { 
     @Override 
     public void run() 
     { 
      try 
      { 
       downloadFile(filename,link); 
      } catch (IOException e) 
      { 
       e.printStackTrace(); 
      } 
     } 
    }); 

    Thread t2 = new Thread(new Runnable() 
    { 
     @Override 
     public void run() 
     { 
      try { 
       counter(link, t1); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 
    }); 

    t1.start(); 
    println("Downloading File..."); 
} 

public void getScreenSize() 
{ 
    Toolkit tk = Toolkit.getDefaultToolkit(); 
    Dimension d = tk.getScreenSize(); 
    println("width = " + d.width + " height = " + d.height); 
} 
public static void downloadFile(String fileName, URL link) throws IOException 
{ 
    InputStream in = new BufferedInputStream(link.openStream()); 
    ByteArrayOutputStream out = new ByteArrayOutputStream(); 
    byte [] buf = new byte[1024]; 
    int n = 0; 
    int count = 0; 

    while (-1 !=(n=in.read(buf))) 
    { 
     out.write(buf, 0, n); 
    } 
    println(count); 
    out.close(); 
    in.close(); 

    byte[] response = out.toByteArray(); 

    FileOutputStream fos = new FileOutputStream(fileName); 
    fos.write(response); 
    fos.close(); 

    println("Download Finished"); 
} 
public static void locate(int row, int col) 
{ 
    System.out.print("\033["+row+";"+col+"H"); 
} 
public static int counter(URL link, Thread t1) throws IOException 
{ 
    int count = 0; 
    link.openConnection(); 
    while(t1.isAlive()) 
    { 
     count++; 
     return count; 
    } 
    return count; 
} 
} 

Answer 1

使用getAndIncrement或incrementAndGet上AtomicInteger，這是一個線程安全的計數器（與初始化爲0櫃檯，如果兩個線程同時調用incrementAndGet那麼你保證計數器將返回1到一個線程， 2到另一個線程，並將有一個最終狀態2）