MyBatis02知识点

深藏阁楼爱情的钟 2023-10-02 19:55 22阅读 0赞

![76d5a74af73a40a2b124a36ccfe4abeb.png][]

dao包

UserMapper接口

package com.itheima.dao;
    
    import com.itheima.pojo.User;
    import org.apache.ibatis.annotations.MapKey;
    import org.apache.ibatis.annotations.Param;
    
    import java.util.List;
    import java.util.Map;
    
    public interface UserMapper {
        /*
            需求1 : 查询id是1的用户信息
            定义接口方法 : User selectUserById(Integer id);
         */
        public abstract User selectUserById(Integer id);
    
        /*
            练习2 ：向数据库添加一行数据
            定义接口方法：void addUser(User user);
         */
        public abstract void addUser(User user);
    
        /*
            练习3 : 根据id修改用户数据
            定义接口方法 : void updateUser(User user);
         */
        public abstract void updateUser(User user);
    
        /*
            练习4 : 根据id删除用户数据
            定义接口方法 : void deleteById(Integer id);
         */
        public abstract void deleteById(Integer id);
    
        /*
            练习5 : 根据id查找用户
            定义接口方法 : User selectUserById2(Integer id);
         */
        public abstract User selectUserById2(Integer id);
    
    
        /*
            练习6 : 根据用户名和性别查询用户
            定义接口方法 : List<User> findUsersByUserNameAndSex(String name,String sex);
         */
        public abstract List<User> findUsersByUserNameAndSex(@Param("name") String name, @Param("sex") String sex);
    
        /*
            练习7 : 向数据库中增加一行数据,接口参数是复杂类型(POJO实体类)
            定义接口方法 : void saveUser(User user);
         */
        public abstract void saveUser(User user);
    
        /*
            练习8 : 根据用户名和性别查询用户信息，入参为Map集合，泛型都是String类型分别表示用户名和性别。
            定义接口方法 : queryByNameAndSex(Map map);
         */
        public abstract List<User> queryByNameAndSex(Map map);
    
    
        /*
            练习9 : 新增一条数据,查看自增主键回填效果
            定义接口方法 : void addUserAndGetId(User user);
        */
        public abstract void addUserAndGetId(User user);
    
    
        /*
           练习10 : 根据用户名和地址查找用户,演示sql注入的问题
           定义接口方法 : List<User> queryUserByNameAndAddress(@Param("name") String name , @Param("address") String address);
         */
        public abstract List<User> queryUserByNameAndAddress(@Param("name") String name, @Param("address") String address);
    
    
        /*
            练习11 : 根据输入的表名统计指定表下的总记录数;
            定义接口方法 : Integer countByTableName(@Param("tableName") String tableName);
         */
        public abstract Integer countByTableName(@Param("tableName") String tableName);
    
        /*
            练习12 : ${}获取配置文件中的值
            因为${key}可以获取外部配置文件中键所对应的值, 所以参数中的标识符( @Param(标识符) ) 不要和配置文件中的key相同
            定义接口方法 : List<User> queryByUserName(String username)
         */
        public abstract List<User> queryByUserName(@Param("username") String username);
    
        /*
            练习13 : 查询id是1的数据，将查询的结果封装到Map<String,Object>中
            定义接口方法 : Map<String,Object> findMapById(@Param("id") Integer id);
         */
        public abstract Map<String, Object> findMapById(@Param("id") Integer id);
    
    
        /*
            练习14 : 获取所有用户,其中key为id值,value为user对象
            @MapKey("id")
            Map<Integer,User> findAllToMap();
         */
        @MapKey("id")
        public abstract Map<Integer, User> findAllToMap();
    
        /*
            练习15 : 查询id是1的用户 , 需要注释核心配置文件中的经典驼峰命名映射
            定义接口方法 : User selectUserById3(@param("id")Integer id);
         */
        public abstract User selectUserById3(@Param("id") Integer id);
    }

pojo文件夹

User类

package com.itheima.pojo;
    
    import java.util.Date;
    
    public class User {
        private Integer id;
        private String userName;
        private Date birthday;
        private Character sex;
        private String address;
    
        public User() {
        }
    
        public User(Integer id, String userName, Date birthday, Character sex, String address) {
            this.id = id;
            this.userName = userName;
            this.birthday = birthday;
            this.sex = sex;
            this.address = address;
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUsername() {
            return userName;
        }
    
        public void setUsername(String userName) {
            this.userName = userName;
        }
    
        public Date getBirthday() {
            return birthday;
        }
    
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
    
        public Character getSex() {
            return sex;
        }
    
        public void setSex(Character sex) {
            this.sex = sex;
        }
    
        public String getAdd() {
            return address;
        }
    
        public void setAddress(String address) {
            this.address = address;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", username='" + userName + '\'' +
                    ", birthday=" + birthday +
                    ", sex=" + sex +
                    ", address='" + address + '\'' +
                    '}';
        }
    }

utils工具包

SessionFactoryUtils

package com.itheima.util;
    
    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;
    
    public class SessionFactoryUtils {
        // 私有构造方法,防止外界创建对象
        private SessionFactoryUtils() {
        }
    
        // 定义成成员变量,整个类去使用
        private static SqlSessionFactory sessionFactory;
    
        /*
            1 在静态代码块中创建会话工厂对象
         */
        static {
            // 1 获取会话工厂创建类对象
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            // 2 加载mybatis核心配置文件,获取会话工厂对象
            // SqlSessionFactory sessionFactory = builder.build(MybatisTest.class.getClassLoader().getResourceAsStream("mybatis-config.xml"));
            try {
                sessionFactory = builder.build(Resources.getResourceAsStream("mybatis-config.xml"));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        /*
            2 编写静态方法得到会话对象，设置自动提交事务
         */
        public static SqlSession getSqlSession() {
            // 获取会话对象 , 设置自动提交事务
            SqlSession sqlSession = sessionFactory.openSession(true);
            return sqlSession;
        }
    
        /*
            3 编写静态方法得到会话对象，方法接收调用者传递的布尔类型，决定是否自动提交事务
         */
        public static SqlSession getSqlSession(boolean isAutoCommit) {
            // 获取会话对象 , 设置自动提交事务
            SqlSession sqlSession = sessionFactory.openSession(isAutoCommit);
            return sqlSession;
        }
    
        /*
            4 编写静态方法接收会话对象，手动提交事务并且关闭会话
         */
        public static void closeSession(SqlSession sqlSession) {
            if (sqlSession != null) {
                // 手动提交事务
                sqlSession.commit();
                // 关闭会话对象
                sqlSession.close();
            }
        }
    
        /*
            5 编写静态方法接收会话对象，回滚事务并且关闭会话
         */
        public static void rollBack(SqlSession sqlSession) {
            if (sqlSession != null) {
                // 回滚事务
                sqlSession.rollback();
                // 关闭会话对象
                sqlSession.close();
            }
        }
    }

UserMapper.xml映射文件

<?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">
    
    
    <mapper namespace="com.itheima.dao.UserMapper">
        
        <select id="selectUserById" parameterType="int" resultType="user">
            select *
            from user
            where id = #{id}
        </select>
    
        
        <insert id="addUser">
            insert into user
            values (null, #{userName}, #{birthday}, #{sex}, #{address})
        </insert>
    
        
        <update id="updateUser">
            update user
            set user_name = #{userName},
                sex       = #{sex}
            where id = #{id}
        </update>
    
        
        <delete id="deleteById">
            delete
            from user
            where id = #{id}
        </delete>
    
        
        <select id="selectUserById2" resultType="user">
            select *
            from user
            where id = #{id}
        </select>
    
        
        <select id="findUsersByUserNameAndSex" resultType="user">
            select *
            from user
            where user_name = #{name}
              and sex = #{sex}
        </select>
    
        
        <insert id="saveUser">
            insert into user
            values (null, #{userName}, #{birthday}, #{sex}, #{add})
        </insert>
    
        
        <select id="queryByNameAndSex" resultType="user">
            select *
            from user
            where user_name = #{userName}
              and sex = #{gender}
        </select>
    
        
        <insert id="addUserAndGetId" useGeneratedKeys="true" keyColumn="id" keyProperty="id">
            insert into user
            values (null, #{userName}, #{birthday}, #{sex}, #{address})
        </insert>
    
        
        <select id="queryUserByNameAndAddress" resultType="user">
            select *
            from user
            where user_name = #{name}
              and address = #{address}
        </select>
    
        
        <select id="countByTableName" resultType="int">
            select count(id)
            from ${tableName}
        </select>
    
        
        <select id="queryByUserName" resultType="user">
            select *
            from user
            where user_name = '${username}'
        </select>
    
        
        <select id="findMapById" resultType="map">
            select *
            from user
            where id = #{id}
        </select>
    
    
        
        <select id="findAllToMap" resultType="map">
            select *
            from user
        </select>
    
        
        <resultMap id="selectUserById3ResultMap" type="User" autoMapping="true">
            <id column="id" property="id"/>
            <result column="user_name" property="userName"/>
        </resultMap>
        <select id="selectUserById3" resultMap="selectUserById3ResultMap">
            select *
            from user
            where id = #{id}
        </select>
    </mapper>

mybatis-config.xml核心配置文件

<?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>
    
        
        <properties resource="db.properties"/>
    
        
        <settings>
            <setting name="mapUnderscoreToCamelCase" value="false"/>
        </settings>
    
        
        <typeAliases>
            <package name="com.itheima.pojo"/>
        </typeAliases>
    
        
        <environments default="development">
            
            <environment id="development">
                
                <transactionManager type="JDBC"/>
                
                <dataSource type="POOLED">
                    
                    <property name="driver" value="${jdbc.driver}"/>
                    
                    <property name="url" value="${jdbc.url}"/>
                    
                    <property name="username" value="${jdbc.username}"/>
                    
                    <property name="password" value="${jdbc.password}"/>
                </dataSource>
            </environment>
        </environments>
    
    
        
        <mappers>
            
    
             <package name="com.itheima.dao"/>
        </mappers>
    </configuration>

[76d5a74af73a40a2b124a36ccfe4abeb.png]: https://img-blog.csdnimg.cn/76d5a74af73a40a2b124a36ccfe4abeb.png