Decorator模式及其他相似的模式

 Decorator模式

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 用户留言板处理的接口
*/
public interface MessageBoardHandler {
    /**
	* @author javahongxi 用户可以利用函数留言
	*/
	public String filter(String msg);
}

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 用户留言板的具体实现
*/
public class MessageBoard implements MessageBoardHandler {

	public String filter(String msg) {
		return "留言板上的内容：" + msg;
	}
}

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 装饰角色
*/
public class MessageBoardDecorator implements MessageBoardHandler {

	private MessageBoardHandler handler;
	 public MessageBoardDecorator(MessageBoardHandler handler) {
	     super();
	     this.handler = handler;
	   }
	 public String filter(String msg) {
		 return handler.filter(msg);
	   }
}

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 具体装饰角色，增加过滤掉HTML标签的功能
*/
public class HtmlFilter extends MessageBoardDecorator {

	public HtmlFilter(MessageBoardHandler handler) {
		super(handler);
	}
	public String filter(String content) {
	    String temp = super.filter(content);
	    temp += "^^过滤掉HTML标签!^^";
	    return temp;
	   }
}

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 具体装饰角色，增加过滤掉政治敏感字眼的功能
*/
public class SensitiveFilter extends MessageBoardDecorator {

	public SensitiveFilter(MessageBoardHandler handler) {
	    super(handler);
	}
	public String filter(String content) {
		String temp = super.filter(content);
	    temp += "^^过滤掉政治敏感的字眼!^^";
	    return temp;
	}
}

package com.whatsmars.tomcat.design.decorator;

/**
* @author javahongxi 客户端测试
*/
public class Test {

	public static void main(String[] args) {
		MessageBoardHandler mb = new MessageBoard();
		String content = mb.filter("一定要学好装饰模式！");
		System.out.println(content);
	      
		mb = new HtmlFilter(new SensitiveFilter(new MessageBoard()));
		content = mb.filter("一定要学好装饰模式！");
		System.out.println(content);
	}
}

console:
留言板上的内容：一定要学好装饰模式！
留言板上的内容：一定要学好装饰模式！^^过滤掉政治敏感的字眼!^^^^过滤掉HTML标签!^^

 

 Adapter模式

package com.whatsmars.tomcat.design.adapter;

/**
 * Created by shenhongxi on 16/4/14.
 */
public class Adaptee {

    public void specificRequest() {
        System.out.println("specific request");
    }
}

package com.whatsmars.tomcat.design.adapter;

/**
 * Created by shenhongxi on 16/4/14.
 */
public interface Target {

    public void request();
}

package com.whatsmars.tomcat.design.adapter;

/**
 * Created by shenhongxi on 16/4/14.
 */
public class Adapter implements Target {

    Adaptee adaptee;

    public void request() {
        adaptee.specificRequest();
    }
}

package com.whatsmars.tomcat.design.adapter;

/**
 * Created by shenhongxi on 16/4/14.
 */
public class Adapter2 extends Adaptee implements Target {
    // 对于我们不必要实现的方法可在Adaptee中作空实现
    public void request() {
        super.specificRequest();
    }
}

  Facade模式

  -- 见一个简单的Servlet容器

 

  个人认为上述三种模式可以统称Wrapper模式，熟练之后我们不必在意它们究竟属于何种设计模式，当然类的命名最好按具体的模式来。