Java躲不过设计模式的坑之代理模式详解

public interface IHandlerService {

    
    void handle();

    
    String print(String content);

    
    void setPrefix(String prefix);
}


@Service
public class HandlerServiceImpl implements IHandlerService {

    
    private String prefix = "default";

    @Override
    public void handle() {
        System.out.println("=======自定义实现类" + prefix + "======");
    }

    @Override
    public String print(String content) {
        System.out.println(prefix + " 实现类输出 -》" + content);
        return prefix + "success";
    }

    @Override
    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }
}

public class MultiDynamicProxy implements InvocationHandler {

    
    private static Map<String, IHandlerService> map = new HashMap<>();
    public static String key = "default";

    private void addElements(String key) {
        if (map.containsKey(key)) return;
        IHandlerService handlerService = new HandlerServiceImpl();
        handlerService.setPrefix(key);
        map.put(key, handlerService);
    }

    public static IHandlerService newInstance(IHandlerService handlerService) {
        MultiDynamicProxy handlerProxy = new MultiDynamicProxy(handlerService);
        // 抽象逻辑接口
        Class<IHandlerService> handlerServiceClass = IHandlerService.class;

        
        return (IHandlerService) Proxy.newProxyInstance(handlerServiceClass.getClassLoader(),
                new Class[]{handlerServiceClass}, handlerProxy);
    }

    public MultiDynamicProxy(IHandlerService handlerService) {
        map.put(key, handlerService);
    }
    
    
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("=====代理类执行====" + proxy.getClass().getSimpleName());
        Object invoke = method.invoke(getElement(), args);
        return invoke;
    }

    private IHandlerService getElement() {
        if (null == map.get(key)) {
            addElements(key);
        }
        return map.get(key);
    }

public static void main(String[] args) {
        IHandlerService handlerService = MultiDynamicProxy.newInstance(new HandlerServiceImpl());
        String s = handlerService.print("客户A");
        System.out.printf("执行结果 => " + s);
    }
    // 输出结果 
    // =====代理类执行====$Proxy0
    // default 实现类输出 -》客户A
    // 执行结果 => defaultsuccess