RandomAccessFile的应用

import java.io.*;class Demo7 {    public static void main(String[] args) throws IOException    {        /*         RandomAccessFile: 不属于IO体系，只能访问文件                           内部既有字节输出流，也有字节输入流                           内部有一个字节数组，可以通过指针设置，所以可以随机        */        //writeData();        readData();    }    //读取数据    public static void readData()throws IOException    {        RandomAccessFile random = new RandomAccessFile("random.txt","r");        //默认指向文件的开头，读取刘能        byte[] arr = new byte[4];        int len = random.read(arr);        int age = random.readInt();        System.out.println(new String(arr,0,len)+","+age);        random.seek(16);//设置指针指向赵四的起始位置        len = random.read(arr);        age = random.readInt();        System.out.println(new String(arr,0,len)+","+age);    }    //随机写入数据    public static void writeData()throws IOException    {        //模式为"rw",那么当文件不存在时会自动创建        RandomAccessFile random = new RandomAccessFile("random.txt","rw");        //默认指向文件的开头        random.write("刘能".getBytes());        random.writeInt(58);        //指针指向哪儿?  8        long pointer = random.getFilePointer();        System.out.println("pointer="+pointer);        //设置指针指向的位置        random.seek(16);        random.write("赵四".getBytes());//指针指向哪儿数据就被写到哪儿        random.writeInt(56);        pointer = random.getFilePointer();        System.out.println("pointer="+pointer);    }}