cglib動態代理和JDK動態代理

maven依賴

cglib動態代理需要jar包支持，CGLib采用了非常底層的字節碼技術。

<!-- https://mvnrepository.com/artifact/cglib/cglib --> <dependency><groupId>cglib</groupId><artifactId>cglib</artifactId><version>3.3.0</version> </dependency>

cglib和JDK動態代理

CGLib采用了非常底層的字節碼技術，其原理是通過字節碼技術為一個類創建子類，并在子類中采用方法攔截的技術攔截所有父類方法的調用，順勢織入橫切邏輯。而JDK動態代理用的是反射，代理的是接口。

cglib示例

被代理類

public class Host {public void rank(){System.out.println("房東租房");} }

代理類

import net.sf.cglib.proxy.Enhancer; import net.sf.cglib.proxy.MethodInterceptor; import net.sf.cglib.proxy.MethodProxy;import java.lang.reflect.Method;public class CGproxy implements MethodInterceptor {private Object target;public void setTarget(Object target) {this.target = target;}public Object getProxy(Class targetClass){if (targetClass == null) return null;Enhancer enhancer = new Enhancer();//設置代理父類enhancer.setSuperclass(targetClass);//設置代理回調方法enhancer.setCallback(this);return enhancer.create();}public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {System.out.println("前置增強");Object result = method.invoke(target,objects);System.out.println("后置增強");return result;} }

測試

public class Demo {public static void main(String[] args) {Host host = new Host();CGproxy cGproxy = new CGproxy();cGproxy.setTarget(host);Host proxy = (Host) cGproxy.getProxy(host.getClass());proxy.rank();} }

JDK動態代理

被代理接口

public interface Rank {public void rank(); }

被代理類

public class Host implements Rank{public void rank() {System.out.println("房東租房");} }

代理類

public class Proxyrank implements InvocationHandler {private Object target;public void setTarget(Object target) {this.target = target;}public Object getProxy(){if (target == null) return null;return Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(),this);}@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {System.out.println(proxy.getClass());System.out.println("前置增強");Object result = method.invoke(target,args);System.out.println("后置增強");return result;} }

測試

public class Demo {public static void main(String[] args) {Rank rank = new Host();Proxyrank proxyrank = new Proxyrank();proxyrank.setTarget(rank);Rank rank1 = (Rank) proxyrank.getProxy();rank1.rank();} }

總結

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