使用字节流和缓冲流复处理文件提高读写速度

使用字节流和缓冲流复处理文件

 @Test
    public void method() throws IOException {
    
    
        File file1 = new File("test1.png");
        File file2 = new File("test2.png");

        FileInputStream fileInputStream = new FileInputStream(file1);
        FileOutputStream fileOutputStream = new FileOutputStream(file2);

        int len = 0;
        byte[] bytes = new byte[1024];
        while((len = fileInputStream.read(bytes)) != -1){
    
    
            fileOutputStream.write(bytes,0,len);
        }
        System.out.println("复制成功");
        fileInputStream.close();
        fileOutputStream.close();
    }

使用缓冲流提高读写效率

开发中使用缓冲流替换基本流。

@Test
    public void method() throws IOException {
    
    

        //1.创建文件
        File file1 = new File("test1.png");
        File file2 = new File("test2.png");

        //2.创建流
        //2.1创建节点流
        FileInputStream fileInputStream = new FileInputStream(file1);
        FileOutputStream fileOutputStream = new FileOutputStream(file2);

        //2.2创建缓冲流
        BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
        BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream);

        // the number of bytes to write.
        int len = 0;
        //每次读的字节数为10
        byte[] bytes = new byte[10];
        while ((len = bufferedInputStream.read(bytes)) != -1){
    
    
            //写
            bufferedOutputStream.write(bytes,0,len);
        }

        System.out.println("复制成功");
        //关闭流的顺序，先关闭外层的流，再关闭内层的流
        bufferedInputStream.close();
        bufferedOutputStream.close();
        //fileInputStream.close();
        //fileOutputStream.close();
    }

• 注意：先关闭外面的流，在关闭内从的流，实际上在关闭外层流的同时，内层的流也会进行关闭，所以关于内层流的关闭可以省略。
• 实际开发中使用try catch finally 确保关闭流。
• 缓冲流的作用是提高文件的读取和写入速度，提高读写速度的原因是：内部提供了一个缓冲区。