自己提的问题以及观点，自己给自己验证，望老师耐心查看

https://class.imooc.com/course/qadetail/274963

1、上个问题中我提出了是，之所以缓冲流更开是优化了直接读写硬盘的操作次数，

以下代码给予验证

验证只缓冲流快与普通流

普通读写流

public class CopytImage {

	public static void main(String[] args) {
		File file1 = new File("sads.jpg");

		try {
			file1.createNewFile();
			Date date1 = new Date();
			FileInputStream fis = new FileInputStream("sda.jpg");
			FileOutputStream fos = new FileOutputStream(file1);
			byte[] by = new byte[1024];
			int n = 0;
			while((n = fis.read(by)) != -1) {
				fos.write(by, 0, n);
			}
			fis.close();
			fos.close();
			Date date2 = new Date();
			System.out.println("普通流读写4m大小图片速度" + (date2.getTime() - date1.getTime()));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

	}

}

结果：普通流读写4m大小图片速度68

缓冲流

public class BufferCopyImage {

	public static void main(String[] args) {
		File file1 = new File("sda.jpg");
		File file2 = new File("sads.jpg");
		try {
			file2.createNewFile();
			Date date1 = new Date();
			BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file1));
			BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file2));
			int n = 0;
			byte[] by = new byte[1024];
			while((n = bis.read(by)) != -1) {
				bos.write(by, 0, n);
			}
			bis.close();
			bos.flush();
			bos.close();
			Date date2 = new Date();
			System.out.println("缓冲流读写4m大小图片速度" + (date2.getTime() - date1.getTime()));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch(IOException e) {
			e.printStackTrace();
		}
	}
}

结果：缓冲流读写4m大小图片速度21

从上面结果可以看出，确实缓冲流快，那么真的缓冲流不管什么时候都快吗

缓冲流2

public class BufferCopyImage {

	public static void main(String[] args) {
		File file1 = new File("sda.jpg");
		File file2 = new File("sads.jpg");
		try {
			file2.createNewFile();
			Date date1 = new Date();
			BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file1), 1);
			BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file2), 1);
			int n = 0;
			byte[] by = new byte[1024];
			while((n = bis.read(by)) != -1) {
				bos.write(by, 0, n);
			}
			bis.close();
			bos.flush();
			bos.close();
			Date date2 = new Date();
			System.out.println("缓冲流读写4m大小图片速度" + (date2.getTime() - date1.getTime()));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch(IOException e) {
			e.printStackTrace();
		}
	}
}

​结果：缓冲流读写4m大小图片速度80

这里可以看出缓冲流竟然慢与普通六=流，以上代码，我把缓冲区的大小改为了极限的1值，也就是说只要有一个字符我就开始读写，这样极大的增加了，直接读写硬盘的次数，那么自然也就慢了，当我改成40000它的速度比默认不设置值更快，默认应该是8000吧，这是我的验证