What is dynamic proxies in Java?

Dynamic proxies in Java are a way to create proxy instances that implement specified interfaces at runtime. This feature is part of the Java Reflection API. Rather than creating a static proxy class for every interface, you can use a dynamic proxy to handle method invocations at runtime, making it easier to adapt to various use cases.

Dynamic proxies allow for the implementation of various design patterns, such as aspect-oriented programming, where behavior such as logging, transaction management, or security checks can be centralized.

To create a dynamic proxy, you can use the `Proxy` class along with an `InvocationHandler`. The `InvocationHandler` is responsible for handling method calls made on the proxy instance.

Example


        import java.lang.reflect.*; 
        
        interface HelloWorld {
            void sayHello();
        }
        
        class HelloWorldInvocationHandler implements InvocationHandler {
            private final HelloWorld helloWorld;
            
            public HelloWorldInvocationHandler(HelloWorld helloWorld) {
                this.helloWorld = helloWorld;
            }
        
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                System.out.println("Before method: " + method.getName());
                Object result = method.invoke(helloWorld, args);
                System.out.println("After method: " + method.getName());
                return result;
            }
        }
        
        public class DynamicProxyExample {
            public static void main(String[] args) {
                HelloWorld original = new HelloWorld() {
                    @Override
                    public void sayHello() {
                        System.out.println("Hello, World!");
                    }
                };
        
                HelloWorld proxy = (HelloWorld) Proxy.newProxyInstance(
                    HelloWorld.class.getClassLoader(),
                    new Class>[]{HelloWorld.class},
                    new HelloWorldInvocationHandler(original));
                
                proxy.sayHello();
            }
        }

What is dynamic proxies in Java?

Example

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What is dynamic proxies in Java?

Example

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