java字节流字节缓冲流读写文件 java 实现字节流和字节缓冲流读写文件时间对比

package cn.itcast.copy; 
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
 
/*
 * 文件复制方式,字节流,一共4个方式
 * 1. 字节流读写单个字节     125250 毫秒
 * 2. 字节流读写字节数组     193 毫秒 OK
 * 3. 字节流缓冲区流读写单个字节  1210 毫秒
 * 4. 字节流缓冲区流读写字节数组  73  毫秒 OK
 */
public class Copy {
	public static void main(String[] args)throws IOException {
		long s = System.currentTimeMillis();
		copy_4(new File("c:\\q.exe"), new File("d:\\q.exe"));
		long e = System.currentTimeMillis();
		System.out.println(e-s);
	}
	/*
	 * 方法,实现文件复制
	 * 4. 字节流缓冲区流读写字节数组
	 */
	public static void copy_4(File src,File desc)throws IOException{
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
		int len = 0 ;
		byte[] bytes = new byte[1024];
		while((len = bis.read(bytes))!=-1){
			bos.write(bytes,0,len);
		}
		bos.close();
		bis.close();
	}
	/*
	 * 方法,实现文件复制
	 * 3. 字节流缓冲区流读写单个字节
	 */
	public static void copy_3(File src,File desc)throws IOException{
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
		int len = 0 ;
		while((len = bis.read())!=-1){
			bos.write(len);
		}
		bos.close();
		bis.close();
	}
	
	/*
	 * 方法,实现文件复制
	 * 2. 字节流读写字节数组
	 */
	public static void copy_2(File src,File desc)throws IOException{
		FileInputStream fis = new FileInputStream(src);
		FileOutputStream fos = new FileOutputStream(desc);
		int len = 0 ;
		byte[] bytes = new byte[1024];
		while((len = fis.read(bytes))!=-1){
			fos.write(bytes,0,len);
		}
		fos.close();
		fis.close();
	}
	
	/*
	 * 方法,实现文件复制
	 * 1. 字节流读写单个字节
	 */
	public static void copy_1(File src,File desc)throws IOException{
		FileInputStream fis = new FileInputStream(src);
		FileOutputStream fos = new FileOutputStream(desc);
		int len = 0 ;
		while((len = fis.read())!=-1){
			fos.write(len);
		}
		fos.close();
		fis.close();
	}
}

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 Demo {
 public static void main(String[] args) throws IOException {
 
 // 获取开始时间
 long start = System.currentTimeMillis();
 
 // 1. 创建一个文件字节输入流对象, 关联源文件
 InputStream in = new FileInputStream("C:\\Users\\Jack\\temp\\柳岩.jpg");
 
 // 2. 创建一个文件字节输出流对象, 关联目标文件
 File file = new File("C:\\Users\\Jack\\myDoc\\ly.jpg");
 if (!file.exists()) {
 // 如果文件不存在, 就需要创建
 File parentFile = file.getParentFile();
 parentFile.mkdirs();
 }
 OutputStream out = new FileOutputStream(file);
 
 // 3. 读取与写入
 byte[] buf = new byte[1024]; //分配1024个字节大小的内存给buf
 int len = -1;
 while ((len = in.read(buf)) != -1) {
 out.write(buf, 0, len);
 }
 
 // 4. 关闭资源
 out.close();
 in.close();
 
 // 获取结束时间
 long end = System.currentTimeMillis();
 
 System.out.println("毫秒: " + (end - start));
 }
}

File file = new File("C:\Users\Jack\myDoc\ly.jpg");