Java Io（数据输入输出流）

Java Io 字节流中的DataInputStream 和 DataOutputStream，使用流更加方便，是流的一个扩展，更方便读取int, long,字符等类型数据。

事例代码如下：

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 {

	/**
	 * 数据输入流事例
	 * @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);

		// 读取数据
		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();
	} 

	/**
	 * 数据输出流事例
	 * @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("我们都是中国人");
		dataOutputStream.writeChars("英国人");
		dataOutputStream.close();

		// 16进制形式显示
		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("文件写入完毕！");
	}

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

		// 写数据
		DataStream.writeData();
		// 读数据
		DataStream.readData();
	}

}