设计模式的应用

谁借莪１个温暖的怀抱￠ 2021-12-13 00:43 236阅读 0赞

/**
     *  单例 + 工厂 + 构造者 + 动态代理
     */
    public class HandelrFactory {
    
    
        /**
         * 接口或者接口的实现类
         */
        private final Class<? extends IHandler> clazz;
    
        private final Object[] params;
    
        /**
         * 调用此方法 会调用静态内部类 调用静态属性方法
         * @return
         */
        private static Builder newInstance(){
            return Instance.instance;
        }
    
        /**
         * 通过builder去调用方法 new对象
         * @return
         */
        public static Builder builder(){
            return newInstance();
        }
    
        private HandelrFactory(Class<? extends IHandler> clazz, Object ... params){
            this.params = params;
            this.clazz = clazz;
        }
    
        /**
         * 静态内部类
         */
        private static class Instance {
            public static final Builder instance = new Builder();
        }
    
        /**
         * 运行方法
         * @throws IllegalAccessException
         * @throws InstantiationException
         */
        public void bind() throws IllegalAccessException, InstantiationException {
            //实例化字节码
            IHandler myHandler = this.clazz.newInstance();
            //动态代理
            InvocationHandler invocationHandler = new MyInvocationHandler(myHandler);
            //代理对象  1. 用来指明生成代理对象使用哪个类装载器 2.Class<?>[] interfaces用来指明生成哪个对象的代理对象 3. 用来指明产生的这个代理对象要做什么事情
            IHandler result = (IHandler) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[]{IHandler.class}, invocationHandler);
            //代理对象执行方法
            result.executor(this.params);
        }
    
        static class Builder {
    
            private Class<? extends IHandler> clazz;
    
            private Object[] params;
    
            /**
             * set方法1
             * @param clazz
             * @return
             */
            public Builder setClazz(Class<? extends IHandler> clazz){
                this.clazz = clazz;
                return this;
            }
    
            /**
             * set方法2
             * @param params
             * @return
             */
            public Builder setParams(Object ... params){
                this.params = params;
                return this;
            }
    
            /**
             * 根据传入参数构建工厂
             * @return
             */
            public HandelrFactory build(){
                return new HandelrFactory(this.clazz, this.params);
            }
    
        }
    
        public static void main(String[] args) throws InstantiationException, IllegalAccessException {
            HandelrFactory
                    .builder()
                    .setClazz(MyHandlerImpl.class)
                    .setParams("12345")
                    .build()
                    .bind();
    
            System.out.println();
    
            HandelrFactory
                    .builder()
                    .setClazz(MyHandlerImpl.class)
                    .setParams("fdsfds")
                    .build()
                    .bind();
        }
    }

接口：

public interface IHandler {
    
        Object executor(Object... param);
    }

接口实现类：

public class MyHandlerImpl implements IHandler {
    
        @Override
        public Object executor(Object... param) {
            for(Object p: param){
                if (p instanceof String){
                    System.out.println("我是接口实现类，我在执行方法");
                   String paramValue = (String)p;
                    System.out.println("方法的参数是"+paramValue);
                }
            }
            return null;
        }
    }

动态代理类：

public class MyInvocationHandler implements InvocationHandler {
    
        //要增强的对象
        private Object target;
    
        public MyInvocationHandler(Object target) {
            this.target = target;
        }
    
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws InvocationTargetException, IllegalAccessException {
            System.out.println("代理对象进行方法增强");
            //某个方法 增强的目标 参数
            method.invoke(target, args);
            return null;
        }
    }