testrandomaccessfile.java

本书是一本为Java学习者在基础内容学习结束后进行课程设计时提供参考的指导书

package apibook.c3.s5;

import java.io.*;

//测试RandomAccessFile类
//功能：对随机文件进行读写
public class TestRandomAccessFile {
  public TestRandomAccessFile() {
  }
  public static void main(String[] args) {
    try {
      String filename = "TestRandomAccessFile.txt";
        RandomAccessFile raf = new RandomAccessFile(filename, "rw");//读写方式打开

        char a = 'a';
        byte b = 2;
        String c = "abc";
        short d = 4;
        byte[] b2 = {'a', 'b', 'c'};

        //写入测试数据
        long file_start = raf.getFilePointer();//得到文件指针
        raf.write(b);//字节
        raf.write(b2, 0, b2.length);//字节数组
        raf.writeBoolean(true);//布尔值
        raf.writeChar(a);//字符
        raf.writeBytes(c);//作为字节写入字符串
        raf.writeChars(c);//作为字符写入字符串
        raf.writeDouble(123.456);//double
        raf.writeFloat(123.456f);//float
        raf.writeInt(678);//int
        raf.writeLong(678l);//long
        raf.writeShort(d);//short
        raf.writeUTF(c);//用utf编码的字符
        raf.writeUTF("abc\n");//用utf编码的字符串
        raf.write(b);//字节
        raf.writeShort(d);//short

        System.out.println("Length of file: " + raf.length());//文件长度

        //读回测试数据
        raf.seek(file_start);//移到文件头

        b2 = new byte[1];
        b = raf.readByte();//读字节
        System.out.println("Byte: " + b);
        raf.read(b2);//读字节数组
        System.out.println("Byte[0]: " + (char)b2[0]);
        raf.read(b2, 0, b2.length);//读字节数组
        System.out.println("Byte[0]: " + (char)b2[0]);
        int ub = raf.readUnsignedByte();//读入无符号的字节
        System.out.println("Unsigned Byte: " + b);
        System.out.println("Boolean: " + raf.readBoolean());
        a = raf.readChar();//读字符
        System.out.println("Char: " + a);

        byte[] b3 = new byte[3];
        raf.readFully(b3);//读字节数组
        System.out.println("readFully: " + (char)b3[0] + (char)b3[1] +
                           (char)b3[2]);
        raf.skipBytes(6); //跳过字符串 'abc'
        double d1 = raf.readDouble();//读double
        float f1 = raf.readFloat();//float
        int i = raf.readInt();//int
        long l = raf.readLong();//long
        short s = raf.readShort();//short
        String str = raf.readUTF();//读utl编码的字符串
        ub = raf.readUnsignedByte();
        int us = raf.readUnsignedShort();
        System.out.println("UTF String" + str);//输出结果

        raf.close();//关闭文件
    } catch (IOException e) {
        System.err.println(e);
    }
  }

}