InvocationHandler 接口位于 java.lang.reflect 反射包，搭配使用可以实现比较丰富的动态功能增减。
直接上代码：
一：必须有准备实现动态代理的Interface功能接口
/*** 准备实现动态代理的接口** @author gbx*/public interface RunMethodInterface {void runA();void runB();}
二：接口的实现类
/*** 接口的实现类** @author gbx*/public class RunMethod implements RunMethodInterface {@Overridepublic void runA() {System.out.println("RunMethod runA...");}@Overridepublic void runB() {System.out.println("RunMethod runB...");}}
三：InvocationHandler 接口的自定义实现，主要在这里实现自定义的功能
import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.UndeclaredThrowableException;/*** 动态代理测试** @author gbx*/public class GbxInvocationHandler implements InvocationHandler {/*** 构造方法引入转化的对象*/private Object object;/*** InvocationHandler的实现类需要提供一个构造器，用来接收目标对象* 否则接口中的method是无法执行的，因为没有对象就没有办法执行对象的方法** @param object 要实现代理的对象*/public GbxInvocationHandler(Object object) {this.object = object;}/*** Processes a method invocation on a proxy instance and returns* the result. This method will be invoked on an invocation handler* when a method is invoked on a proxy instance that it is* associated with.** @param proxy the proxy instance that the method was invoked on* @param method the {@code Method} instance corresponding to*the interface method invoked on the proxy instance. The declaring*class of the {@code Method} object will be the interface that*the method was declared in, which may be a superinterface of the*proxy interface that the proxy class inherits the method through.* @param args an array of objects containing the values of the*arguments passed in the method invocation on the proxy instance,*or {@code null} if interface method takes no arguments.*Arguments of primitive types are wrapped in instances of the*appropriate primitive wrapper class, such as*{@code java.lang.Integer} or {@code java.lang.Boolean}.* @return the value to return from the method invocation on the* proxy instance. If the declared return type of the interface* method is a primitive type, then the value returned by* this method must be an instance of the corresponding primitive* wrapper class; otherwise, it must be a type assignable to the* declared return type. If the value returned by this method is* {@code null} and the interface method's return type is* primitive, then a {@code NullPointerException} will be* thrown by the method invocation on the proxy instance. If the* value returned by this method is otherwise not compatible with* the interface method's declared return type as described above,* a {@code ClassCastException} will be thrown by the method* invocation on the proxy instance.* @throws Throwable the exception to throw from the method* invocation on the proxy instance. The exception's type must be* assignable either to any of the exception types declared in the* {@code throws} clause of the interface method or to the* unchecked exception types {@code java.lang.RuntimeException}* or {@code java.lang.Error}. If a checked exception is* thrown by this method that is not assignable to any of the* exception types declared in the {@code throws} clause of* the interface method, then an* {@link UndeclaredThrowableException* } containing the* exception that was thrown by this method will be thrown by the* method invocation on the proxy instance.* @see UndeclaredThrowableException*/@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {Object invoke = null;try {//执行目标方法前执行的任意逻辑System.out.println("GbxInvocationHandler 方法前执行的自定义逻辑...");//实现代理的对象方法执行invoke = method.invoke(object, args);//执行目标方法后执行的任意逻辑System.out.println("GbxInvocationHandler 方法后执行的自定义逻辑...");} catch (Exception e) {System.out.println("GbxInvocationHandler 方法执行异常:" + e.getMessage());e.printStackTrace();}return invoke;}}
四：调用方式
import java.lang.reflect.InvocationHandler;import java.lang.reflect.Proxy;/*** 测试动态代理** @author gbx*/public class TestA {public static void main(String[] args) {RunMethodInterface runMethod = new RunMethod();runMethod.runA();runMethod.runB();System.out.println("============================分割线============================");//开始构建自定义代理InvocationHandler gbxInvocationHandler = new GbxInvocationHandler(runMethod);//成功创建目标对象的代理RunMethodInterface proxyRunMethod = (RunMethodInterface) Proxy.newProxyInstance(gbxInvocationHandler.getClass().getClassLoader(), runMethod.getClass().getInterfaces(), gbxInvocationHandler);//用代理对象调用相关方法，则执行目标方法和自定义代理中的相关逻辑proxyRunMethod.runA();System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");proxyRunMethod.runB();}}
五：查看程序执行结果
RunMethod runA...RunMethod runB...============================分割线============================GbxInvocationHandler 方法前执行的自定义逻辑...RunMethod runA...GbxInvocationHandler 方法后执行的自定义逻辑...>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>GbxInvocationHandler 方法前执行的自定义逻辑...RunMethod runB...GbxInvocationHandler 方法后执行的自定义逻辑...
Over！
发布前，看到扯淡的官方提示，说质量低，不会获得推荐。好吧，能看到此博文的皆是有缘之人！
