JAVA基础（常用流数据输入输出流）

1，什么是数据输入输出流

• DataInputStream, DataOutputStream可以按照基本数据类型大小读写数据

• 例如按Long大小写出一个数字, 写出时该数据占8字节. 读取的时候也可以按照Long类型读取, 一次读取8个字节.

 

2，使用方式

import java.io.DataInputStream;

import java.io.DataOutputStream;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;





public class Demo09_Data {





    /**

     * @param args

     * @throws IOException

     * 00000000 00000000 00000011 11100101    int类型997

     * 11100101

     * 00000000 00000000 00000000 11100101

     */

    public static void main(String[] args) throws IOException {

        //demo1();

        //demo2();

        //demo3();

        DataInputStream dis = new DataInputStream(new FileInputStream("h.txt"));

        int x = dis.readInt();

        int y = dis.readInt();

        int z = dis.readInt();

        

        System.out.println(x);

        System.out.println(y);

        System.out.println(z);

        

        dis.close();

    }





    public static void demo3() throws FileNotFoundException, IOException {

        DataOutputStream dos = new DataOutputStream(new FileOutputStream("h.txt"));

        dos.writeInt(997);

        dos.writeInt(998);

        dos.writeInt(999);

        dos.close();

    }





    public static void demo2() throws FileNotFoundException, IOException {

        FileInputStream fis = new FileInputStream("h.txt");

        int x = fis.read();

        int y = fis.read();

        int z = fis.read();

        

        System.out.println(x);

        System.out.println(y);

        System.out.println(z);

        

        fis.close();

    }





    public static void demo1() throws FileNotFoundException, IOException {

        FileOutputStream fos = new FileOutputStream("h.txt");

        fos.write(997);

        fos.write(998);

        fos.write(999);

        

        fos.close();

    }

}

 

【2】结果