一、Mybatis与JDBC的区别

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public class Person {

    private Long pid;

    private String pname;

    public Long getPid() {

        return pid;

    }

    public void setPid(Long pid) {

        this.pid = pid;

    }

    public String getPname() {

        return pname;

    }

    public void setPname(String pname) {

        this.pname = pname;

    }

}

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package com.ys.dao;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

import javax.swing.DebugGraphics;

import com.ys.bean.Person;

public class CRUDDao {

    //MySQL数据库驱动

    public static String driverClass = "com.mysql.jdbc.Driver";

    //MySQL用户名

    public static String userName = "root";

    //MySQL密码

    public static String passWord = "root";

    //MySQL URL

    public static String url = "jdbc:mysql://localhost:3306/test";

    //定义数据库连接

    public static Connection conn = null;

    //定义声明数据库语句,使用 预编译声明 PreparedStatement提高数据库执行性能

    public static PreparedStatement ps = null;

    //定义返回结果集

    public static ResultSet rs = null;

    /**

     * 查询 person 表信息

     * @return：返回 person 的 list 集合

     */

    public static List<Person> readPerson(){

        List<Person> list = new ArrayList<>();

        try {

            //加载数据库驱动

            Class.forName(driverClass);

            //获取数据库连接

            conn = DriverManager.getConnection(url, userName, passWord);

            //定义 sql 语句,?表示占位符

            String sql = "select * from person where pname=?";

            //获取预编译处理的statement

            ps = conn.prepareStatement(sql);

            //设置sql语句中的参数，第一个为sql语句中的参数的?(从1开始)，第二个为设置的参数值

            ps.setString(1, "qzy");

            //向数据库发出 sql 语句查询，并返回结果集

            rs = ps.executeQuery();

            while (rs.next()) {

                Person p = new Person();

                p.setPid(rs.getLong(1));

                p.setPname(rs.getString(2));

                list.add(p);

            }

        } catch (Exception e) {

            e.printStackTrace();

        }finally{

            //关闭数据库连接

            if(rs!=null){

                try {

                    rs.close();

                } catch (SQLException e) {

                    e.printStackTrace();

                }

            }

            if(ps!=null){

                try {

                    ps.close();

                } catch (SQLException e) {

                    e.printStackTrace();

                }

            }

            if(conn!=null){

                try {

                    conn.close();

                } catch (SQLException e) {

                    e.printStackTrace();

                }

            }

        }

        return list;

    }

    public static void main(String[] args) {

        System.out.println(CRUDDao.readPerson());

    }

}