package com.jdbc.tools;

import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.handlers.BeanHandler;

import org.apache.commons.dbutils.handlers.BeanListHandler;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import java.sql.SQLException;

import java.util.List;

public abstract class BasicDAOImpl2 <T> {

    //type代表T的实际类型

    private Class<T> type;

    private QueryRunner qr=new QueryRunner();

    //在创建子类对象时，一定会调用父类构造器，默认调用父类无参构造

    public  BasicDAOImpl2(){

        //this是正在new的对象

        //clazz就是正在new对象的那个子类的类型的Class对象

        Class<? extends BasicDAOImpl2> clazz = this.getClass();

        Type t=clazz.getGenericSuperclass();

        ParameterizedType pt=(ParameterizedType) t;

        Type[] types=pt.getActualTypeArguments();

        type= (Class) types[0];

    }

    public int update(String sql, Object...args) throws SQLException {

        return qr.update(JDBCToolsV3.getConnection(),sql,args);

    }

    public  T getBean(String sql, Object...args) throws SQLException {

        return  qr.query(JDBCToolsV3.getConnection(),sql,new BeanHandler<>(type),args);

    }

    public List<T> getBeanList(String sql, Object... args) throws SQLException {

        return  qr.query(JDBCToolsV3.getConnection(),sql,new BeanListHandler<>(type),args);

    }

}