思路

BaseAction

package com.itheima.web.action.base;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
/**
 * 表現層通用實現
 * @author Administrator
 *
 * @param <T>
 */
public class BaseAction<T> extends ActionSupport implements ModelDriven<T> {

    private T model;
    //model相當于new User
    //actualTypeArguments[0];相當于獲得User.class
    
    
    public BaseAction() {
        ParameterizedType genericSuperclass = (ParameterizedType)this.getClass().getGenericSuperclass();
        //獲得BaseAction上聲明的泛型數組
        Type[] actualTypeArguments = genericSuperclass.getActualTypeArguments();
        Class<T> entityClass=(Class<T>) actualTypeArguments[0];
        
        try {
            //通過反射創建實例對象
            model=entityClass.newInstance();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
    public T getModel() {
        return model;
    }

}