简单的IO流文本复制实例

import java.io.*;
public class copyTest
{
 public static void main(String[] args)
 {
  copy();
 }
 public static void copy()
 {
  FileWriter fw=null;
  FileReader fr=null;
  try
  {
   fw=new FileWriter("demo3.txt");
   fr=new FileReader("Rand.java");
   char[] buf=new char[1024];
   int len=0;
   while((len=fr.read(buf))!=-1)
   {
    fw.write(buf,0,len);
   }
  }
  catch(IOException e)
  {
   //System.out.println(e.toString());
   throw new RuntimeException("读写失败");
  }
  finally
  {
   if(fr!=null)
   try
   {
    fr.close();
   }
   catch(IOException e)
  {
   System.out.println(e.toString());
   //throw new RuntimeException("读写失败");
  }
  
   if(fw!=null)
   try
   {
    fw.close();
   }
   catch(IOException e)
  {
   System.out.println(e.toString());
   //throw new RuntimeException("读写失败");
  }
  }
   
 }
}