在执行以下代码后,复制的图片相当大,还不能打开,请哪位高手帮忙解释...

import java.io.*;

public class PictureCopyTest {

 public static void main(String[] args) {   FileInputStream fis = null;   FileOutputStream fos = null;   try {    fis = new FileInputStream("D:\\test\\lee.jpg");    fos = new FileOutputStream("D:\\WallPaper\\lee.jpg");    byte[] b = new byte[512];    int n = 0;// 记录读取到内存的字节数    while ((n = fis.read()) != -1) { // 读取到-1的时候停止读取     fos.write(b);    }   } catch (Exception e) {    e.printStackTrace();   } finally {    try {     fis.close();     fos.close();    } catch (IOException e) {     e.printStackTrace();    }   }  } }