使用Java的多線程和IO流寫一個文件復制功能類

創建一個復制功能類，繼承Thread類，重寫run()方法，把FileInputStream和FileOutputStream輸入輸出流寫在run()方法內。示例代碼如下：

import java.io.*;
import java.text.DecimalFormat;
/**
 * 文件復制類
 * @author Administrator
 *
 */
public class FileCopy extends Thread {
    
    private File src;//待讀取的源文件
    private File dest;//待寫入的目標文件
    
    public FileCopy(String src,String dest){
        this.src = new File(src);
        this.dest = new File(dest);
    }

    @Override
    public void run() {
        FileInputStream is = null;
        FileOutputStream os = null;
        
        try {
            is = new FileInputStream(src);
            os = new FileOutputStream(dest);
            
            byte[] b = new byte[1024];
            int length = 0;
            
            //獲取源文件大小
            long len = src.length();
            //已復制文件的字節數
            double temp = 0 ; 
            //數字格式化，顯示百分比
            DecimalFormat df = new DecimalFormat("##.00%");
            while((length = is.read(b))!=-1){
                //輸出字節
                os.write(b, 0, length);
                //獲取已下載的大小，並且轉換成百分比
                temp += length;
                double d = temp/len;
                System.out.println(src.getName()+"已復制的進度："+df.format(d));
            }
            System.out.println(src.getName()+"復制完成！");
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            try {
                if (is != null) {
                    is.close();
                } 
                if(os!=null){
                    os.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
                
    }

}

在測試類中調用復制功能類

public class FileCopyTest {

    public static void main(String[] args) {

        FileCopy cf = new FileCopy("D:\\720.txt","D:\\test\\1.txt");
        FileCopy cf2 = new FileCopy("D:\\721.txt","D:\\test\\2.txt");
        FileCopy cf3 = new FileCopy("D:\\123.txt","D:\\test\\3.txt");
        cf.start();
        cf2.start();
        cf3.start();
        
    }

}