IO字节缓冲流

版权声明： https://blog.csdn.net/weixin_40072979/article/details/83626057

缓冲流是对字节流的缓冲，可以加快字节流的效率。使用缓冲流的前提是必须使用字节流，我们只需要关闭最外面的流就行了，内部的留会自动关闭。

1：缓冲字节输入流

package com.jianshun;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

/**
 * 四个步骤: 分段读取 文件字节输入流  加入缓冲流
 * 1、创建源
 * 2、选择流
 * 3、操作
 * 4、释放资源
 */
public class BufferedTest01 {

	public static void main(String[] args) {
		//1，创建流
		File src = new File("abc.txt");
		//2，选择流
		InputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(src));
			//3，操作（分段读取）
			byte[] flush = new byte[1024];//缓冲容器
			int len = -1;
			while((len = in.read(flush))!=-1){
				//字节数组--》字符串 （解码）
				String str = new String(flush,0,len);
				System.out.println(str);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally{
			//4，释放资源
			if(null!=in){
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
	}

}

 2：缓冲字节输出流

package com.jianshun;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * 四个步骤: 分段读取 文件字节输入流  加入缓冲流
 * 1、创建源
 * 2、选择流
 * 3、操作
 * 4、释放资源
 */
public class BufferedTest02 {

	public static void main(String[] args) {
		File src = new File("dest.txt");
		OutputStream out = null;
		try {
			out = new BufferedOutputStream(new FileOutputStream(src));
			String msg = "IO is so easy\r\n";
			byte[] datas = msg.getBytes();
			out.write(datas, 0, datas.length);
			out.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally{
			if(null!=out){
				try {
					out.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
	}

}

我们可以改进之前复制文件的方法，用字节缓冲流复制文件

package com.jianshun;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
 * 缓冲字节流拷贝文件
 * @author Administrator
 */
public class Copy02 {

	public static void main(String[] args) {
		copy("abc.txt","dest.txt");
	}
	
	public static void copy(String srcPath,String destPath){
		//,2，创建源
		File src = new File(srcPath);
		File dest = new File(destPath);
		//,2，选择流
		InputStream in = null;
		OutputStream out = null;
		try {
			in = new BufferedInputStream(new FileInputStream(src));
			out =new BufferedOutputStream(new FileOutputStream(dest));
			//3，操作，分段读取
			byte[] flush = new byte[1024];
			int len = -1;//接收长度
			while((len = in.read(flush)) != -1){
				out.write(flush, 0, len);//分段写出
			}
			out.flush();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally{
			//4，释放资源,分别关闭，先打开的后关闭
			if(out != null){
				try {
					out.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			
			if(in !=null){
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	public static void copy2(String srcPath,String destPath){
		File src = new File(srcPath);//源头
		File dest = new File(destPath);
		try(InputStream in = new BufferedInputStream(new FileInputStream(srcPath));
			OutputStream out = new BufferedOutputStream(new FileOutputStream(destPath))) {
			//操作，分段读取
			byte[] flush = new byte[1024];
			int len = -1;
			while((in.read(flush))!=-1){
				out.write(flush, 0, len);
			}
			out.flush();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e1) {
			e1.printStackTrace();
		}
	}
}