java文件操作练习代码 读取某个盘符下的文件

import java.io.bufferedreader;
import java.io.file;
import java.io.fileinputstream;
import java.io.filenotfoundexception;
import java.io.filereader;
import java.io.ioexception;
import java.io.inputstream;
import java.io.reader;

public class ioread {

 /**
  * @param args
  * 文件的读写
  */
 public static void main(string[] args) {
  // todo auto-generated method stub
  try {

   // 方法一

   bufferedreader br = new bufferedreader(new filereader(new file(

   "d:/project/transfar/doc/1.txt")));

   // stringbuilder bd = new stringbuilder();

   stringbuffer bd = new stringbuffer();

   while (true) {

    string str = br.readline();

    if (str == null) {

     break;

    }
    system.out.println(str);

    bd.append(str);

   }

   br.close();

   // system.out.println(bd.tostring());

   // 方法二

   inputstream is = new fileinputstream(new file("d:/project/transfar/doc/1.txt"));

   byte b[] = new byte[integer.parseint(new file("d:/project/transfar/doc/1.txt").length()

   + "")];

   is.read(b);
   system.out.write(b);

   system.out.println();

   is.close();

   // 方法三

   reader r = new filereader(new file("d:/project/transfar/doc/1.txt"));

   char c[] = new char[(int) new file("d:/project/transfar/doc/1.txt").length()];

   r.read(c);

   string str = new string(c);

   system.out.print(str);

   r.close();

  } catch (runtimeexception e) {

   // todo auto-generated catch block

   e.printstacktrace();

  } catch (filenotfoundexception e) {

   // todo auto-generated catch block

   e.printstacktrace();

  } catch (ioexception e) {

   // todo auto-generated catch block

   e.printstacktrace();

  }

 }

}