”万丈高楼平地起“——如何从“建筑师”角度打造【装饰者设计模式】

/**
 * 定义【抽象构建角色】：GatewayComponent
 * GatewayComponent:相当与建筑师设计好高楼的建造目标
 */
public abstract class GatewayComponent {

    /**
     * 定义共同行为的方法标准
     */
    public abstract void service();

}

/**
 * 【网关获取基本参数】，BasicComponentGateway【被装饰的类】
 * BasicComponentGateway：相当于建房子的【地基】
 */
public class BasicComponentGateway extends GatewayComponent {
    public void service() {
        System.out.println("第一步>>> 网关中获取基本的操作实现...");
    }
}

/**
 * 抽象装饰者：AbstractDecorator，定义【被装饰者】与【具体装饰者】共同行为
 * AbstractDecorator：相当于工人怎么去建好每一层楼
 */
public class AbstractDecorator extends GatewayComponent {

    public GatewayComponent gatewayComponent;

    public AbstractDecorator(GatewayComponent gatewayComponent){
        this.gatewayComponent = gatewayComponent;
    }
    public void service() {
        if(gatewayComponent!=null){
            gatewayComponent.service();
        }
    }
}

/**
 * 网关新增日志收集LogDecorator，【装饰者】
 * LogDecorator：相当于地基之上搭建第一层
 */
public class LogDecorator extends AbstractDecorator {
    public LogDecorator(GatewayComponent gatewayComponent) {
        super(gatewayComponent);
    }
    @Override
    public void service() {
        super.service();
        System.out.println("第二步>>> 网关中新增日志收集..");
    }
}

/**
 * 网关新增API接口限流具体操作【装饰者】
 * ApiLimitDecorator：相当于在第第一层楼上建造第二层
 */
public class ApiLimitDecorator extends AbstractDecorator {
    public ApiLimitDecorator(GatewayComponent gatewayComponent) {
        super(gatewayComponent);
    }
    @Override
    public void service() {
        super.service();
        System.out.println("第三步>>> 网关中新增API接口的限流...");

    }
}

public class FactoryGateway {

    public static GatewayComponent getGatewayComponent() {
        //第二层->第一层->地基
        return new ApiLimitDecorator(new LogDecorator(new BasicComponentGateway()));
    }

    public static void main(String[] args) {
        GatewayComponent gatewayComponent = FactoryGateway.getGatewayComponent();
        //地基->第一层->第二层
        gatewayComponent.service();
    }
}