Java装饰模式

package com.czie.d4_decorator_pattern;

/**
 装饰模式

 定义父类：InputStream
 定义实现类：FileInputStream 继续父类 定义功能
 定义装饰实现类：BufferedInputStream 继承父类 定义功能 包装原始类，增强功能。
 */
public class DecoratorPattern {
    public static void main(String[] args)  {
        InputStream is = new BufferedInputStream(new FileInputStream());
        System.out.println(is.read());
        System.out.println(is.read(new byte[3]));
    }
}

package com.czie.d4_decorator_pattern;


/**
 装饰类：继承InputStream 拓展原始类的功能
 */
public class BufferedInputStream extends InputStream {
    private InputStream is;
    public BufferedInputStream(InputStream is){
        this.is=is;
    }

    @Override
    public int read() {
        System.out.println("提供8KB的缓冲区，提高读数据性能~~~~");
        return is.read();
    }

    @Override
    public int read(byte[] buffer) {
        System.out.println("提供8KB的缓冲区，提高读数据性能~~~~");
        return is.read(buffer);
    }

}

package com.czie.d4_decorator_pattern;


/**
 共同父类
 */
public abstract class InputStream{
    public abstract int read() ;
    public abstract int read(byte[] buffer) ;
}

package com.czie.d4_decorator_pattern;


import java.util.Arrays;

/**
 原始类
 */
public class FileInputStream extends InputStream {

    @Override
    public int read() {
        System.out.println("低性能的方式读取了一个字节a");
        return 97;
    }

    @Override
    public int read(byte[] buffer) {
        buffer[0] = 97;
        buffer[1] = 98;
        buffer[2] = 99;
        System.out.println("低性能的方式读取了一个字节数组：" + Arrays.toString(buffer));
        return 3;
    }
}