Java中IO流 RandomAccessFile类实例详解

package com.test.io;import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;import java.util.Arrays;public class RafDemo {  public static void main(String[] args) throws IOException {    File demo = new File("demo");    if (!demo.exists()) {      demo.mkdir();    }    File file = new File(demo, "raf.dat");    if (!file.exists()) {      file.createNewFile();    }    RandomAccessFile raf = new RandomAccessFile(file, "rw");    System.out.println(raf.getFilePointer());        raf.write('A');//一个char型占两个字节，但是write一次只写入一个字节（A字符的后八位）    System.out.println(raf.getFilePointer());    raf.write('B');        int i = 0x7fffffff;    raf.write(i >>> 24);//写入i的高八位    raf.write(i >>> 16);    raf.write(i >> 8);    raf.write(i);    System.out.println(raf.getFilePointer());    //直接写入一个int    raf.writeInt(i);        String s = "你";    byte[] b = s.getBytes("utf8");    raf.write(b);    System.out.println(raf.length());        //读文件，必须把指针移到头部    raf.seek(0);    //一次性读取，把文件中的内容都读到字节数组中    byte[] buf = new byte[(int) raf.length()];    raf.read(buf);    System.out.println(Arrays.toString(buf));    for (byte c : buf) {      System.out.print(Integer.toHexString(c & 0xff) + " ");    }    //关闭文件    raf.close();  }}

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