MyBatis入门

• 导入引用并设置构建目录

    <!--导入依赖-->
    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!--mybatis-->
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

• 创建Mybatis核心配置文件（mybatis-config.xml）

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--configuration核心配置文件-->
<configuration>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://192.168.137.100:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;allowPublicKeyRetrieval=true"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/kuang/dao/UserMapper.xml"/>
    </mappers>
</configuration>

• 创建Mybatis工具类（MybatisUtils.java）

package com.kuang.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

//sqlSessionFactory --> sqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static{
        try {
            //使用Mybatis第一步：获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    //既然有了 SqlSessionFactory，顾名思义，我们就可以从中获得 SqlSession 的实例了。
    // SqlSession 完全包含了面向数据库执行 SQL 命令所需的所有方法。
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

}

• 创建实体类

package com.kuang.pojo;

import lombok.Data;

@Data
public class User {
    private int id;
    private String name;
    private String pwd;

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name=name;
        this.pwd=pwd;

    }
}

• 创建UserMapper接口

package com.kuang.dao;

import com.kuang.pojo.User;
import org.apache.ibatis.annotations.Param;

import java.util.List;
import java.util.Map;

public interface UserMapper {

    //查询全部用户
    List<User> getUserList();

    //根据id查询用户
    User selectUserById(int id);

    //通过密码和名字查询用户
    User selectUserByNP(@Param("username") String username, @Param("pwd") String pwd);

    User selectUserByNP2(Map<String,Object> map);

    //添加一个用户
    int addUser(User user);

    //修改一个用户
    int updateUser(User user);

    //根据id删除用户
    int deleteUserById(int id);

    //根据姓名模糊查询
    List<User> selectUserLike(String value);

    //根据姓名模糊查询2
    List<User> selectUserLike2(String value);
}

• 创建UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.kuang.dao.UserMapper">

    <!--select查询语句-->
    <select id="getUserList" resultType="com.kuang.pojo.User">
       select * from user
   </select>

    <select id="selectUserById" resultType="com.kuang.pojo.User" parameterType="int">
        select * from user where id=#{id}
    </select>

    <select id="selectUserByNP" resultType="com.kuang.pojo.User">
        select * from user where name=#{username} and pwd=#{pwd}
    </select>

    <select id="selectUserByNP2" resultType="com.kuang.pojo.User" parameterType="map">
        select * from user where name = #{username} and pwd = #{pwd}
    </select>

    <insert id="addUser" parameterType="com.kuang.pojo.User">
        insert into user (id,name,pwd) values (#{id},#{name},#{pwd})
    </insert>

    <update id="updateUser" parameterType="com.kuang.pojo.User">
        update user set name=#{name},pwd=#{pwd} where id = #{id}
    </update>

    <delete id="deleteUserById" parameterType="int">
        delete from user where id = #{id}
    </delete>

    <select id="selectUserLike" resultType="com.kuang.pojo.User">
        select * from user where name like #{value}
    </select>

    <!--存在SQL注入漏洞-->
    <select id="selectUserLike2" resultType="com.kuang.pojo.User">
        select * from user where name like "%"#{value}"%"
    </select>
</mapper>