MyBatis配置(1)

1.先导入jar包

jar.PNG

项目分支图

1.PNG

2.创建实体类User对象

    public class User {
        private int a_id;
        private String a_name;
        private String a_pwd;
        
        public int getA_id() {
            return a_id;
        }
        public void setA_id(int a_id) {
            this.a_id = a_id;
        }
        public String getA_name() {
            return a_name;
        }
        public void setA_name(String a_name) {
            this.a_name = a_name;
        }
        public String getA_pwd() {
            return a_pwd;
        }
        public void setA_pwd(String a_pwd) {
            this.a_pwd = a_pwd;
        }
        public User() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    }
    

3.配置mybatis.cfg.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>

    <typeAliases>
        <typeAlias alias="user" type="com.senchen.entity.User" />
    </typeAliases>
    
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/test3" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <!-- 注册UsersMapper.xml文件， usersMapper.xml位于com.senchen.mapper这个包下，所以resource写成com/senchen/mapper/UserMapper.xml -->
        <mapper resource="com/senchen/mapper/UsersMapper.xml" />
    </mappers>
</configuration>

4.配置实体类的专属ORM文件(UsersMapper.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">
    <mapper namespace="com.senchen.mapper.UsersMapper">
    <select id="findById" parameterType="int" resultType="com.senchen.entity.User">
        select * from admin where a_id=#{id}
    </select>
    
    <select id="findAll" resultType="user"><!-- 也可以写成resultType="com.senchen.entity.User" -->
        select * from admin
    </select>
    
    <insert id="save" parameterType="user"><!--user 也可以写成com.senchen.entity.User    一个意思 -->
        insert into admin values(#{a_id},#{a_name},#{a_pwd})
    </insert>
    
</mapper>

5.测试类

    package com.senchen.test;

    import java.io.InputStream;
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import com.senchen.entity.User;
    
    public class Test {
    public static void main(String[] args) {
        
        //web项目classpath    reqeust.getSession().getServletContext().getRealPath("/")
        InputStream is = Test.class.getResourceAsStream("/mybatis.cfg.xml");
        
        //构建sqlSession的工厂
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
    
        //获取一个sqlSession
        SqlSession session = sessionFactory.openSession();
        
        //执行查询id值返回一个唯一user对象的sql路径
        User uu = session.selectOne("com.senchen.mapper.UsersMapper.findById",2);
        System.out.println("查询返回一个唯一user对象"+uu);
        
        //执行查询返回多个user对象集合  的sql路径
        List<User> ulist = session.selectList("com.senchen.mapper.UsersMapper.findAll");
            //System.out.println("---集合 " + (ulist!=null?ulist.size():-1));
        System.out.println("行查询返回多个user对象集合"+ulist);
        
        <!--插入数据 -->
        User u = new User();
        u.setA_id(4);
        u.setA_name("张三");
        u.setA_pwd("abc123");
        session.insert("com.senchen.mapper.UsersMapper.save",u);
        session.commit();
        
        }
    }

查询结果：

    查询返回一个唯一user对象com.senchen.entity.User@2cba5bdb
    查询返回多个user对象集合[com.senchen.entity.User@53343ed0, com.senchen.entity.User@b07f45d, com.senchen.entity.User@373c0b53]

0.PNG