数据输入输出流(了解)

数据输入输出流(了解)

• 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

  • DataOutputStream(OutputStream)，writeInt()，writeLong()

      DataOutputStream dos = new DataOutputStream(new FileOutputStream("b.txt"));
      dos.writeInt(997);
      dos.writeInt(998);
      dos.writeInt(999);
      
      dos.close();
    

  • DataInputStream(InputStream)，readInt()，readLong()

      DataInputStream dis = new DataInputStream(new FileInputStream("b.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();
    

package com.heima.otherio;

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 Demo06_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();
	}
}