Java IO输入输出流 FileWriter 字符流-优快云博客

本文通过四个不同的方法对比了文件复制操作的效率，分别使用了节点流和缓冲流进行单字节及批量字节的读写操作，并记录了每种方法所需的时间，展示了缓冲流在提高读写性能方面的作用。

字节缓冲流

//为什么要使用包装流，使用包装流是为了提高读写操作的性能。
public class Packing_flowDemo {
	public static void main(String[] args) throws Exception {
		File file = new File("file/packing_flow.txt");
		//包装流的写法，缓冲区内存大小。1024*8=8192  (byte)
//		BufferedOutputStream packing = new BufferedOutputStream(new FileOutputStream(file, true));
//		packing.write("大家好！你好吗？how are your !".getBytes());
//		packing.close();
     //包装流的读写操作。
		BufferedInputStream outPacking = new BufferedInputStream(new FileInputStream(file));
		byte[] buffer = new byte[1024];
		int len = -1;
		while ((len = outPacking.read(buffer)) != -1) {
			System.out.println(new String(buffer, 0, len));
		}
	}
}

public static void main(String[] args) throws IOException {//为了代码看起来美观一些，直接抛出去
		File file=new File("moves/许嵩 - 素颜 - 现场版.mp3");
		File file1=new File("moves/许嵩 - 素颜.mp3");
		//text(file, file1);
		//text2(file, file1);
		//text3(file, file1);
		text4(file, file1);
	}
	private static void text(File file,File file1) throws IOException {
		//节点流的方法，一个一个字节的读和写
		long begin=System.currentTimeMillis();
		FileInputStream in=new FileInputStream(file);
		FileOutputStream out =new FileOutputStream(file1);
		int len=-1;
		while((len=in.read())!=-1){
			out.write(len);
		}
		in.close();
		out.close();
		System.out.println(System.currentTimeMillis()-begin);//5547毫秒
	}
	
	private static void text2(File file,File file1) throws IOException {
		//缓冲流的写法，一个一个字节的读和写
		long begin=System.currentTimeMillis();
		BufferedInputStream in=new BufferedInputStream(new FileInputStream(file));
		BufferedOutputStream out =new BufferedOutputStream(new FileOutputStream(file1));
		int len=-1;
		while(in.read()!=-1){
			out.write(len);
		}
		in.close();
		out.close();
		System.out.println(System.currentTimeMillis()-begin);//63毫秒
	}
	
	private static void text3(File file,File file1) throws IOException {
		//节点流的写法，一次性读取1024个字节
		long begin=System.currentTimeMillis();
		FileInputStream in=new FileInputStream(file);
		FileOutputStream out =new FileOutputStream(file1);
		int len=-1;
		byte[] buffer=new byte[1024];
		while((len=in.read(buffer))!=-1){
			out.write(buffer,0,len);
		}
		in.close();
		out.close();
		System.out.println(System.currentTimeMillis()-begin);//38毫秒
	}
	
	private static void text4(File file,File file1) throws IOException {
		//缓冲流的写法，一次性读取1024个字节
		long begin=System.currentTimeMillis();
		BufferedInputStream in=new BufferedInputStream(new FileInputStream(file));
		BufferedOutputStream out =new BufferedOutputStream(new FileOutputStream(file1));
		int len=-1;
		byte[] buffer=new byte[1024];
		while((len=in.read(buffer))!=-1){
			out.write(buffer,0,len);
		}
		in.close();
		out.close();
		System.out.println(System.currentTimeMillis()-begin);//4毫秒
	}

转载于:https://www.cnblogs.com/jiangxifanzhouyudu/p/6721140.html