package org.jrest4guice.dao;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.concurrent.RejectedExecutionException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jrest4guice.dao.actions.Action;
import org.jrest4guice.dao.actions.ActionContext;
import org.jrest4guice.dao.actions.ActionRegister;
import com.google.inject.Inject;
import com.google.inject.Singleton;
/**
* DAO 动态代理类<br>
* 由该对象负责 DAO 接口的代理实例的创建，并由该对象负责拦截 DAO 接口的方法的执行，将执行操作转交为特定的<code>Action</code>类执行。
* @author <a href="mailto:gzyangfan@gmail.com">gzYangfan</a>
*/
@Singleton
public class DynamicProxy implements InvocationHandler {
private final static Log log = LogFactory.getLog(DynamicProxy.class);
@Inject
private ActionRegister register;
/**
* 创建指定 DAO 接口的代理实现类
* @param <T> DAO接口类型
* @param daoClazz DAO接口的 class
* @return
*/
@SuppressWarnings("unchecked")
public <T> T createDao(Class<T> daoClazz) {
return (T) Proxy.newProxyInstance(daoClazz.getClassLoader(), new Class[] { daoClazz }, this);
}
@SuppressWarnings("unchecked")
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Action action = getAction(method);
if (action == null) {
String msg = "无法获取" + proxy.getClass() + "." + method.getName() + "方法声明的Action实例。";
log.error(msg);
throw new RejectedExecutionException(msg);
} else {
ActionContext context = action.getContext();
context.setAction(action);
return context.execute(method, args);
}
}
@SuppressWarnings("unchecked")
private Action getAction(Method method) {
Annotation[] annotations = method.getAnnotations();
for (Annotation annotation : annotations) {
Class<? extends Annotation> clazz = annotation.annotationType();
if (register.isActionAnnotation(clazz)) {
Action action = register.createAction(annotation);
action.setAnnotation(annotation);
return action;
}
}
return null;
}
}