设计模式相关

1、观察者模式

//被观察者
    public interface observer{
        public void update(String s);
    }
    
    //观察著
    public interface observable{
        
        public void registerObserver(observer o);
        public void notifyUpdate();
    }
    //微信公众号
    public static class Wechat implements observable{
        
        public observer observer;

        @Override
        public void registerObserver(observer o) {
            this.observer = o;
        }
              
        @Override
        public void notifyUpdate() {
            observer.update("有新的内容推送啦！");       
        }
        
    }
    //用户
    public static class User implements observer{

        @Override
        public void update(String s) {
            System.out.println(s);
            
        }
    }

      //测试代码
      Wechat wechat = new Wechat();
      User user = new User();
      wechat.registerObserver(user);
      wechat.notifyUpdate();

https://www.cnblogs.com/luohanguo/p/7825656.html

2、适配器模式、

//目标接口
public interface Target {
 
    //这是源类Adapteee没有的方法
    public void Request(); 
}
//源接口
public class Adaptee {
    
    public void SpecificRequest(){
    }
}
//适配器
class Adapter implements Target{  
    // 直接关联被适配类  
    private Adaptee adaptee;  
    
    // 可以通过构造函数传入具体需要适配的被适配类对象  
    public Adapter (Adaptee adaptee) {  
        this.adaptee = adaptee;  
    }  
    
    @Override
    public void Request() {  
        // 这里是使用委托的方式完成特殊功能  
        this.adaptee.SpecificRequest();  
    }  
}
//测试类
public class AdapterPattern {
    public static void main(String[] args){
        //需要先创建一个被适配类的对象作为参数  
        Target mAdapter = new Adapter(new Adaptee())；
        mAdapter.Request();
     
    }
}

https://www.jianshu.com/p/9d0575311214

3、代理模式

interface Subject{
    void request();
}

class RealSubject implements Subject{
    public void request(){
        System.out.println("request");
    }
}

class Proxy implements Subject{
    private Subject subject;
    public Proxy(){
    //编译时确定
        this.subject = new RealSubject() ;
    }
    public void request(){
    //访问控制
       if(){
          subject.request();
        }else{
          ....
        }       
    }
}
//测试类
public class ProxyDemo {
    public static void main(String args[]){    
        Proxy p = new Proxy();
        p.request();
    }
}

4、装饰者模式

//抽象构件角色

public interface Component {
    
    public void sampleOperation();
    
}
//具体构件角色

public class ConcreteComponent implements Component {

    @Override
    public void sampleOperation() {
        // 写相关的业务代码
    }
}
//装饰角色

public class Decorator implements Component{
    private Component component;
    
    public Decorator(Component component){
        this.component = component;
    }

    @Override
    public void sampleOperation() {
        // 委派给构件
        component.sampleOperation();
    }   
}
//具体装饰角色
public class ConcreteDecoratorA extends Decorator {

    public ConcreteDecoratorA(Component component) {
        super(component);
    }
    
    @Override
    public void sampleOperation() {
      // 写相关的业务代码
　　　super.sampleOperation();
     // 写相关的业务代码
    }
}

https://www.jianshu.com/p/d7f20ae63186

5代理模式、装饰者模式的区别

• 这两个设计模式看起来很像。对装饰器模式来说，装饰者（decorator）和被装饰者（decoratee）都实现同一个 接口。对代理模式来说，代理类（proxy class）和真实处理的类（real class）都实现同一个接口。
• 装饰器模式通常将原始对象作为一个参数传给装饰者的构造器，代理模式通常是在代理类中创建一个对象的实例。
• 代理模式主要是控制对某个特定对象访问，而装饰模式主要是为了给对象添加行为。
  https://blog.csdn.net/chenchaofuck1/article/details/51030524
  https://blog.csdn.net/lulei9876/article/details/39994825
  https://www.cnblogs.com/panxuejun/p/6127832.html

6、建造者模式（builder）

• 用于构建复杂对象

public class MyDialog {
    private String title;
    private String content;
    private String icon;

     static class MyBuilder {

        MyDialog dialog;

        public MyBuilder() {
            dialog = new MyDialog();
        }

        public MyBuilder setTile(String title) {
            dialog.title = title;
            return this;
        }

        public MyBuilder setContent(String content) {
            dialog.content = content;
            return this;
        }

        public MyBuilder setIcon(String icon) {
            dialog.icon = icon;
            return this;
        }

        public MyDialog create() {
            return dialog;
        }
    }

    @Override
    public String toString() {
        return "Dialog [title=" + title + ", content=" + content + ", icon=" + icon + "]";
    }

}

MyDialog.MyBuilder builder = new MyDialog.MyBuilder();
        MyDialog dialog = builder.setContent("内容").setTile("标题").setIcon("图标").create();
        System.out.println(dialog.toString());

https://www.jianshu.com/p/4dcc723b676e
https://blog.csdn.net/carson_ho/article/details/54910597

7、责任链模式

//抽象处理者
public abstract class Handler{
        //下一节点的处理者
        protected  Handler nextHandler;
        //满足条件则处理，不满足条件交给下一节点进行处理
        public abstract void handRequest(int i) ;
    }
    
    public class Handler1 extends Handler{
        @Override
        public void handRequest(int i) {
            if(i < 1) {
                System.out.println(i);
            }else {
                nextHandler.handRequest(i);
            }
            
        }
    }
    
    public class Handler2 extends Handler{
        @Override
        public void handRequest(int i) {
            if(i < 2) {
                System.out.println(i);
            }else {
                nextHandler.handRequest(i);
            }
            
        }
    }

         //测试代码
       Handler1 handler1 = new Handler1();
       Handler1 handler2 = new Handler2();
       handler1.nextHandler = handler2;
       handler1.handRequest(3);