Java读取文件和写入文件

package com.manze.stu;
 import java.io.*;   
   
 public class IOTest {  
  
      public static void samples() throws IOException {  
  
            //1. 这是从文件中逐行读入数据   
   
            BufferedReader in = new BufferedReader(new FileReader("D:\\info.txt" ));  
             String s="",s2="";
             while((s=in.readLine())!=null)
                   	 s2+=s+"\n";
              in.close();
            //2. 这是从一个字符串中逐个读入字节   
            StringReader in1 = new StringReader(s2);  
            int c;  
            while ((c = in1.read()) != -1)  
                       System .out.print((char)c);  
   
            //3. 这是将读取的字符串写入另个文件   
            try {  
                       BufferedReader in2 = new BufferedReader(new StringReader(s2));  
                       PrintWriter out1 = new PrintWriter(new BufferedWriter(new FileWriter("D:\\IODemo.txt" )));  
                      int lineCount = 1;  
                       while ((s = in2.readLine()) != null )  
                                  out1.println(s);  
                        out1.close();  
             } catch (EOFException e) {  
                       System .err.println("End of stream" );  
             }  
        } 
      public static void main(String[] arg)
      {
    	  try {
			IOTest.samples();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
      }
   
 }