Java Io（數據輸入輸出流）

Java Io 字節流中的DataInputStream 和 DataOutputStream，使用流更加方便，是流的一個擴展，更方便讀取int, long,字符等類型數據。

事例代碼如下：

package com.dcz.io;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class DataStream {
	
	/**
	 * 數據輸入流事例
	 * @throws IOException
	 */
	public static void readData() throws Exception{
		
		File file = new File("demo.txt");
		if(!file.exists()){
			throw new IllegalAccessException("文件不存在！");
		}
		InputStream fileInputStream = new FileInputStream(file);
		DataInputStream dataInputStream = new DataInputStream(fileInputStream);
		
		// 讀取數據
		System.out.println(dataInputStream.readInt());
		System.out.println(dataInputStream.readFloat());
		System.out.println(dataInputStream.readInt());
		System.out.println(dataInputStream.readDouble());
		System.out.println(dataInputStream.readUTF());
		System.out.println(dataInputStream.readChar());
		System.out.println(dataInputStream.readChar());
		System.out.println(dataInputStream.readChar());
		dataInputStream.close();
	} 
	
	/**
	 * 數據輸出流事例
	 * @throws IOException
	 */
	public static void writeData() throws IOException{
		
		File file = new File("demo.txt");
		if(!file.exists()){
			file.createNewFile();
		}
		OutputStream fileOutputStream = new FileOutputStream(file);
		DataOutputStream dataOutputStream = new DataOutputStream(fileOutputStream);
		dataOutputStream.writeInt(300);
		dataOutputStream.writeFloat(12.38f);
		dataOutputStream.writeInt(-220);
		dataOutputStream.writeDouble(10.5);
		dataOutputStream.writeUTF("我們都是中國人");
		dataOutputStream.writeChars("英國人");
		dataOutputStream.close();
		
		// 16進制形式顯示
		InputStream fileInputStream = new FileInputStream(file);
		int bytes = 0;
		while((bytes = fileInputStream.read()) != -1){
			System.out.print(Integer.toHexString(bytes) + ",");
		}
		fileInputStream.close();
		
		System.out.println("");
		System.out.println("文件寫入完畢！");
	}

	public static void main(String[] args) throws Exception  {
		
		// 寫數據
		DataStream.writeData();
		// 讀數據
		DataStream.readData();
	}

}