package test;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;

public class RandomAccess {
 
 
 public static void main(String[] args) {
  try {
   File file = new File("C:\\img\\666.txt");
   
   //打开文件
   RandomAccessFile randomAccess = new RandomAccessFile(file,"rwd"); //访问文件 
   Long lenth = randomAccess.length(); //获取文件长度
   System.out.println("lenth:"+lenth);
   randomAccess.seek(4); //设置指针位置
   
   //读取文件
   int c = randomAccess.read(); //读取一个字节
   System.out.println("c:"+c);
   System.out.println("c:"+(char)c); //转换为字符
   
   byte[] b = new byte[3]; //读取字节数字，创建数组
   randomAccess.read(b, 1, 2); //从指针1处读取两个字节写入数组b中
   String s = new String(b); //转换为字符串
   System.out.println("byte:"+s); //输出
   
   //写入文件
   File file2 = new File("C:\\img\\777.txt");
   if(!file2.getParentFile().exists()){
    file2.getParentFile().mkdirs();
   } 
   file2.createNewFile();
   RandomAccessFile randomAccess2 = new RandomAccessFile(file2,"rwd"); //访问文件 
   randomAccess2.write(b); //写入字符数组
   
   //关闭文件
   randomAccess.close();
   randomAccess2.close();
   
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
  
 }

}