自定义字节流缓冲区，演示缓冲区的工作原理

- 日理万妓 2022-08-09 03:17 117阅读 0赞

package bytetest;
    
    import java.io.IOException;
    import java.io.InputStream;
    
    public class MyBufferedInputStream {
    
        private InputStream in;
        private byte[] buf = new byte[1024];
        private int pos = 0;
        private int count = 0;
    
        public MyBufferedInputStream(InputStream in) {
            this.in = in;
        }
    
        // 一次读一个字节，从缓冲区（字节数组）获取
        public int myRead() throws IOException {
    
            // 通过in对象读取硬盘上数据，并存储buf中。
            if (count == 0) {
                count = in.read(buf);
                pos = 0;
                byte b = buf[pos];
                count--;
                pos++;
                return b & 255;     //向上提升到int，防止读到 11111111（-1）而意外终止，
            } else if (count > 0) {
                byte b = buf[pos];
                count--;
                pos++;
                return b & 255;
            }
            return -1;
        }
    
        public void myClose() throws IOException {
            in.close();
        }
    }

测试

package bytetest;
    
    import java.io.BufferedOutputStream;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    
    public class CopyMp3 { 
    
        public static void main(String[] args) throws IOException {
            copyMp3_2();
        }
    
    
        public static void copyMp3_2() throws IOException {
            MyBufferedInputStream bufis = new MyBufferedInputStream(
                    new FileInputStream("1.mp3"));
            BufferedOutputStream bufos = new BufferedOutputStream(
                    new FileOutputStream("3.mp3"));
    
            int by=0;
    
            while((by=bufis.myRead())!=-1){     //将byte强转成int
                bufos.write(by);    //将读到的 int 类型的数据强转回 byte 再写入
            }
    
            bufos.close();
            bufis.myClose();
        }
    }