Use JDKDyProxy to simulate AOP implementation

Packagetest; importjava. lang. reflect. *; *** CreatedwithIntelliJIDEA. * User: e513569* Date: 12313 * Time: 4: 39PM * TochangethistemplateuseFile | Settings | FileTemplates. * interfaceSomeInterface {publicStringsomeMethod (

Package test; import java. lang. reflect. *;/*** Created with IntelliJ IDEA. * User: e5131_* Date: 12/3/13 * Time: PM * To change this template use File | Settings | File Templates. */interface SomeInterface {public String someMethod (

package test;import java.lang.reflect.*;/** * Created with IntelliJ IDEA. * User: e513480 * Date: 12/3/13 * Time: 4:39 PM * To change this template use File | Settings | File Templates. */interface SomeInterface {    public String someMethod(String val);}class SomeBean implements SomeInterface {    @Override    public String someMethod(String val) {        System.out.println("some method invoked, val=" + val);        if ("throw1".equalsIgnoreCase(val)) {            throw new IllegalArgumentException("This is a Exception");        } else if ("throw2".equalsIgnoreCase(val)) {            throw new IllegalStateException("This is a Exception");        }        return val;    }}class InvocationHandlerAdapter implements InvocationHandler {    private Object proxyedObject;    private Advice advice;    @Override    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {        Object ret = null;        try {            advice.doBeforeInvoke(proxyedObject, method, args);            ret = method.invoke(proxyedObject, args);            advice.doAfterSuccessInvoke(proxyedObject, method, args);        } catch (InvocationTargetException e) {            advice.doAfterThrows(proxyedObject, method, args, e.getCause());        } finally {            advice.doAfterInvoke(proxyedObject, method, args);        }        return ret;    }    public Object getProxyedObject() {        return proxyedObject;    }    public void setProxyedObject(Object proxyedObject) {        this.proxyedObject = proxyedObject;    }    public Advice getAdvice() {        return advice;    }    public void setAdvice(Advice advice) {        this.advice = advice;    }}interface Advice {    void doBeforeInvoke(Object proxyedObject, Method method, Object[] args);    void doAfterSuccessInvoke(Object proxyedObject, Method method, Object[] args);    void doAfterInvoke(Object proxyedObject, Method method, Object[] args);    void doAfterThrows(Object proxyedObject, Method method, Object[] args, Throwable e) throws Throwable;}public class ProxyTest {    private static  T createProxy(String beanName, Advice advice) {        T proxy = null;        try {            InvocationHandlerAdapter handler = new InvocationHandlerAdapter();            handler.setAdvice(advice);            Class toBeProxedClass = Class.forName(beanName);            handler.setProxyedObject(toBeProxedClass.newInstance());            proxy = (T) Proxy.newProxyInstance(toBeProxedClass.getClassLoader(), toBeProxedClass.getInterfaces(), handler);        } catch (Exception e) {            throw new IllegalArgumentException("Failed to create proxy.", e);        }        return proxy;    }    public static void main(String[] args) {        try {            String beanName = "test.SomeBean";            Advice advice = new Advice() {                @Override                public void doBeforeInvoke(Object proxyedObject, Method method, Object[] args) {                    System.out.println("doBeforeInvoke");                }                @Override                public void doAfterSuccessInvoke(Object proxyedObject, Method method, Object[] args) {                    System.out.println("doAfterSuccessInvoke");                }                @Override                public void doAfterInvoke(Object proxyedObject, Method method, Object[] args) {                    System.out.println("doAfterInvoke");                }                @Override                public void doAfterThrows(Object proxyedObject, Method method, Object[] args, Throwable e) throws Throwable {                    System.out.println("doAfterThrows, the exception is " + e);                    if (e instanceof IllegalStateException) {                        //throw2                        throw e;                    }                }            };            SomeInterface proxy = createProxy(beanName, advice);            System.out.println("------------begin---------------------");            String val = proxy.someMethod("hello");            System.out.println("returned val=" + val);            System.out.println("------------end---------------------");            System.out.println("------------begin---------------------");            val = proxy.someMethod("throw1");            System.out.println("returned val=" + val);            System.out.println("------------end---------------------");            System.out.println("------------begin---------------------");            try {                val = proxy.someMethod("throw2");                System.out.println("should not get to here");            } catch (IllegalStateException e) {                System.out.println("should get to here");            }            System.out.println("returned val=" + val);            System.out.println("------------end---------------------");        } catch (Exception e) {            e.printStackTrace();        }    }}

Original article address: Use JDK DyProxy to simulate AOP implementation. Thank you for sharing it with the original author.