persistenceobjectmethodinterceptor.java

软件设计课做的一个类似Hibernate的O/R Mapping的框架

package cn.edu.nju.software.sd.torm.impl;

import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
import cn.edu.nju.software.sd.torm.exception.IllegalOperationException;

/**
 * The PersistenceObjectMethodInterceptor class is used to 
 * encapsulate a object. This is for the purpose of method
 * interception.
 * 
 * @author Yinfei XU
 *
 */
public class PersistenceObjectMethodInterceptor implements MethodInterceptor {
	private Set<Object> deletedObjects;

	private Method interceptedMethod;

	private Class clazz;

	/**
	 * @param c
	 * @param interceptedMethod
	 */
	public PersistenceObjectMethodInterceptor(Class c, Method interceptedMethod) {
		super();
		deletedObjects = new HashSet<Object>();
		this.clazz = c;
		this.interceptedMethod = interceptedMethod;
	}

	/**
	 * @return
	 */
	public Object getEnhancedObject() {
		Enhancer enhancer = new Enhancer();
		enhancer.setSuperclass(clazz);
		enhancer.setCallback(this);
		return enhancer.create();
	}

	/* (non-Javadoc)
	 * @see net.sf.cglib.proxy.MethodInterceptor#intercept(java.lang.Object, java.lang.reflect.Method, java.lang.Object[], net.sf.cglib.proxy.MethodProxy)
	 */
	public Object intercept(Object o, Method m, Object[] args, MethodProxy proxy)
			throws Throwable {
		Iterator itr = deletedObjects.iterator();
		while(itr.hasNext()){
			if(itr.next() == o ){
				throw new IllegalOperationException("The call to method is not allowed: " + m.getName());
			}
		}

		if (m.equals(interceptedMethod)) {
			throw new IllegalOperationException(
					"The call to method is not allowed: " + m.getName());
		} else {
			return proxy.invokeSuper(o, args);
		}
	}

	/**
	 * @param obj
	 */
	public void addDeletedObject(Object obj) {
		this.deletedObjects.add(obj);
	}
}