使用Java的多线程和IO流写一个文件复制功能类

创建一个复制功能类，继承Thread类，重写run()方法，把FileInputStream和FileOutputStream输入输出流写在run()方法内。示例代码如下：

 import java.io.*;
 import java.text.DecimalFormat;
 /**
  * 文件复制类
  * @author Administrator
  *
  */
 public class FileCopy extends Thread {

     private File src;//待读取的源文件
     private File dest;//待写入的目标文件

     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;

             //获取源文件大小
             long len = src.length();
             //已复制文件的字节数
             double temp = 0 ;
             //数字格式化，显示百分比
             DecimalFormat df = new DecimalFormat("##.00%");
             while((length = is.read(b))!=-1){
                 //输出字节
                 os.write(b, 0, length);
                 //获取已下载的大小，并且转换成百分比
                 temp += length;
                 double d = temp/len;
                 System.out.println(src.getName()+"已复制的进度："+df.format(d));
             }
             System.out.println(src.getName()+"复制完成！");

         } 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();
             }
         }

     }

 }

在测试类中调用复制功能类

 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();

     }

 }