本文介绍了java中两种动态代理的实现方法,Spring的动态代理也是基于这两种方法的。直接附上源码:
1、JDK实现
使用JDK实现动态代理必须使用接口
- 接口Work.java
public interface Work {
public void work();
}
- 实现类WorkImpl.java
public class WorkImpl implements Work {@Override
public void work() {
System.out.println("我在工作");
}}
- 一个添加日志的代理类LogHandler.java,这里用到了log4j。
public class LogHandler<T> implements InvocationHandler{public T target;
private static Logger logger = Logger.getLogger(LogHandler.class);
public LogHandler(T target){
this.target = target;
}@SuppressWarnings("unchecked")
public T getInstance(){
return (T) Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
}@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
logger.warn("start");
Object result = method.invoke(target, args);
logger.warn("end");
return result;
}}
- 最后测试类Test.java
public class Test {
public static void main(String[] args) {
Work w = new WorkImpl();
w.work();
Work logWork = new LogHandler<Work>(w).getInstance();
logWork.work();
}
}
2、CGLIB实现
CGLIB实现动态代理是对JDK动态代理的一种补充,可以不实现接口就能动态代理。
首先需要引入CGLIB的相关jar包(cglib-nodep-2.2.2.jar)
- 业务相关类WorkImpl.java
public class WorkImpl {public void work() {
System.out.println("我在工作");
}}
- CGLIB动态代理类LogHandler.java,同样是添加日志信息
public class LogHandler<T> implements MethodInterceptor{public T target;
private static Logger logger = Logger.getLogger(LogHandler.class);
public LogHandler(T target){
this.target = target;
}@SuppressWarnings("unchecked")
public T getInstance(){
//使用CGLIB生成子类,并委托代理对象代理
return (T) Enhancer.create(target.getClass(), this);
}@Override
public Object intercept(Object obj, Method method, Object[] args,
MethodProxy proxy) throws Throwable {
logger.warn("start!");
Object result=proxy.invokeSuper(obj, args);
logger.warn("end!");
return result;
}}
- 测试类Test.java
public class Test {
public static void main(String[] args) {
WorkImpl w = new WorkImpl();
w.work();
WorkImpl logWork = new LogHandler<WorkImpl>(w).getInstance();
logWork.work();
}
}
Java中两种动态代理的实现