/* ==================================================================   
 * Created [2009-4-27 下午11:32:55] by Jon.King 
 * ==================================================================  
 * TSS 
 * ================================================================== 
 * mailTo:jinpujun@hotmail.com
 * Copyright (c) Jon.King, 2009-2012 
 * ================================================================== 
*/

package com.jinhe.tss.core.cachepool.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;

import org.apache.log4j.Logger;

import com.jinhe.tss.core.exception.BusinessException;


/** 
 * <p> BaseInvocationHandler.java </p> 
 * InvocationHandler基类
 * 
 * @author Jon.King 2007-1-5
 */

public abstract class BaseInvocationHandler implements InvocationHandler{
    protected Logger log = Logger.getLogger(this.getClass());
    
    private Object target;  //拦截的对象
    private String[] invokeMethods; //需要拦截的方法，为空则拦截任何方法
   
    /**
     * @param target  拦截的对象
     * @param invokeMethods  需要拦截的方法
     */
    public BaseInvocationHandler(Object target, String[] invokeMethods){
        this.invokeMethods = invokeMethods;
        this.target = target;
    }
    
    public BaseInvocationHandler(Object target){
        this.target = target;
    }
    
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //如果没有指定拦截的方法列表，则拦截接口中所有方法。
        boolean invoke = (invokeMethods == null 
                || (invokeMethods.length > 0 && Arrays.asList(invokeMethods).contains(method.getName())));
        Object returnVal;
        Object beforeReturnVal = null;
        try {
            if(invoke){
                //执行拦截前操作
                beforeReturnVal = (Long) before(target, method, args);
            }
            // 执行方法，并获取返回值
            returnVal = method.invoke(target, args);
            return returnVal;
        } catch (InvocationTargetException e) {
            throw e.getTargetException();
        } catch (Exception e) {
            throw new BusinessException("unexpected invocation exception: " + e.getMessage());
        } finally {
            if(invoke) {
                //执行拦截后操作
                after(target, method, args, beforeReturnVal);
            }
        }
    }

    /**
     * 定义方法执行前的操作
     * @param target
     * @param method
     * @param args
     * @return
     */
    protected abstract Object before(Object target, Method method, Object[] args);
    /**
     * 定义方法执行后的操作
     * @param target
     * @param method
     * @param args
     * @param beforeReturnVal
     */
    protected abstract void after(Object target, Method method, Object[] args, Object beforeReturnVal);
}