java读写文件

//=============================读文件

package fier;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;

public class sdsd {

/**
   * @param args
   */
public static void main(String[] args) {
   read("E:\\123.txt");
}

public static void read(String file) {
   String s = null;
   StringBuffer sb = new StringBuffer();
   File f = new File(file);
   if (f.exists()) {
    System.out.println("文件存在");

    try {
     BufferedReader br = new BufferedReader(new InputStreamReader(
       new FileInputStream(f)));

     while ((s = br.readLine()) != null) {
      sb.append(s);
     }
     System.out.println(sb);
    } catch (Exception e) {
     e.printStackTrace();
    }
   }else{
    System.out.println("文件不存在!");
   }
}
}