mybatis实战：二、mybatis xml 方式的基本用法

r囧r小猫 2023-10-04 20:11 31阅读 0赞

注释都在代码里，最好复制了再看！

--------------------

### 1.创建表 ###

### 2.插入数据 ###

CREATE TABLE sys_user(
    id BIGINT NOT NULL AUTO_INCREMENT COMMENT '用户 ID',
    user_name VARCHAR(50) COMMENT '用户名',
    user_password VARCHAR(50) COMMENT '密码',
    user_email VARCHAR(50) COMMENT '邮箱',
    user_info TEXT COMMENT '简介',
    head_img BLOB COMMENT '头像',
    create_time DATETIME COMMENT '创建时间',
    PRIMARY KEY (id) 
    );
    ALTER TABLE sys_user COMMENT '用户表';
    
    CREATE TABLE sys_role(
    id BIGINT NOT NULL AUTO_INCREMENT COMMENT '角色 ID',
    role_name VARCHAR(50) COMMENT '角色名',
    enabled INT COMMENT '有效标志',
    create_by BIGINT COMMENT '创建人',
    create_time DATETIME COMMENT '创建时间',
    PRIMARY KEY (id) 
    );
    ALTER TABLE sys_role COMMENT '角色表';
    
    CREATE TABLE sys_prvilege(
    id BIGINT NOT NULL AUTO_INCREMENT COMMENT '权限  ID',
    privilege_name VARCHAR(50) COMMENT '权限名称',
    privilege_url VARCHAR (200) COMMENT '权限 URL',
    PRIMARY KEY (id) 
    );
    ALTER TABLE sys_prvilege COMMENT '权限表';
    
    CREATE TABLE sys_user_role( 
    user_id BIGINT COMMENT '用户 ID ',
    role_id BIGINT COMMENT '角色 ID'
    );
    ALTER TABLE sys_user_role COMMENT '用户角色关联表';
    
    CREATE TABLE sys_role_prvilege(
    role_id BIGINT COMMENT '角色ID',
    privilege_id BIGINT COMMENT 'ID' 
    );
    ALTER TABLE sys_role_prvilege COMMENT '角色权限关联表';
    
    INSERT INTO sys_user VALUES ('2','admin','123456','admin@mybatis.tk','管理员',NULL,'2016-04-01 17:00:58'); 
    INSERT INTO sys_user VALUES ('1001','test','123456','test@mybatis.tk','测试用户',NULL,'2016-04-01 17:00:58'); 
    INSERT INTO sys_role VALUES ('1','管理员','1','1','2016-04-01 17:02:14'); 
    INSERT INTO sys_role VALUES ('2','普通用户','1','1','2016-04-01 17:02:34');
    INSERT INTO sys_user_role VALUES ('1','1'); 
    INSERT INTO sys_user_role VALUES ('1','2');  
    INSERT INTO sys_user_role VALUES ('3','2'); 
    INSERT INTO sys_prvilege VALUES ('1','用户管理','/users'); 
    INSERT INTO sys_prvilege VALUES ('2','角色管理','/roles'); 
    INSERT INTO sys_prvilege VALUES ('3','系统日志','/logs'); 
    INSERT INTO sys_prvilege VALUES ('4','人员维护','/persons'); 
    INSERT INTO sys_prvilege VALUES ('5','单位维护','/companies'); 
    INSERT INTO sys_role_prvilege VALUES ('1','l'); 
    INSERT INTO sys_role_prvilege VALUES ('1','1001'); 
    INSERT INTO sys_role_prvilege VALUES ('1','2');  
    INSERT INTO sys_role_prvilege VALUES ('2','4'); 
    INSERT INTO sys_role_prvilege VALUES ('2','5');

### 3.创建实体类 ###

package tk.mybatis.simple.model;
    
    import java.util.Date;
    
    import lombok.Data;
    
    @Data
    public class SysUser {
        private Long id;
        private String userName;
        private String userPassword;
        private String userInfo;
        private byte[] headImg;
        private Date createTime;
        private String userEmail;
    }

> @Date可以省略get、set方法，要导入依赖、下载插件才可以使用
> 
>     <dependency>
>                 <groupId>org.projectlombok</groupId>
>                 <artifactId>lombok</artifactId>
>                 <version>1.18.24</version>
>             </dependency>
> 
> ![63a6014bfe9a46a59caf21d5a228cb06.png][]

package tk.mybatis.simple.model;
    
    import lombok.Data;
    
    @Data
    public class SysUserRole {
        private Long userId;
        private Long roleId;
    }

### 4.Mapper ###

创建一下文件

![c85dc6fb272a4c53a209a0ea7a5ea5b1.png][]

xml：

需要注意 是＜mapper ＞根标签 name space 属性。当 app 接口和 XM 文件关联的时候，命名空间口amespace 值就需要配置成接口的全限定名称，例如 UserMapper 接口对 应的 tk.mybat. simple.mapper.UserMapper内部就是通过这个值将接口和XML 关联起来的。

mybatis-config.xml

### 5.UserMapper.xml ###

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    
    
    
    <mapper namespace="tk.mybatis.simple.mapper.UserMapper">
        
        
        <resultMap id="userMap" type="tk.mybatis.simple.model.SysUser">
    
            <id property="id" column="id"/>
            <result property="userName" column="user_name"/>
            <result property="userPassword" column="user_password"/>
            <result property="userEmail" column="user_email"/>
            <result property="userInfo" column="user_info"/>
            <result property="headImg" column="head_img" jdbcType="BLOB"/>
            <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
    
    
    
    
    
    
    
    
    
    
    
    
        </resultMap>
    
        <select id="selectById" resultMap="userMap">
    
            select * from sys_user where id = #{id}
    
        </select>
    
        <select id="selectAll1" resultType="tk.mybatis.simple.model.SysUser" >
        select id,
        user_name userName,
        user_password userPassword,
        user_email userEmail,
        user_info userInfo ,
        head img headImg,
        create_time createTime
        from sys_user
    </select>
    
    
        <select id= "selectAll2" resultType="tk.mybatis.simple.model.SysUser" >
        select id, user_name , user_password, user_email , user_info, head_img, create_time from sys_user
    </select>
    </mapper>

### 6.BaseMapperTest ###

### 7.CountryMapperTest ###

package tk.mybatis.simple.mapper;
    
    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 org.junit.Assert;
    import org.junit.BeforeClass;
    import org.junit.Test;
    import tk.mybatis.simple.model.Country;
    import tk.mybatis.simple.model.SysUser;
    
    import java.io.IOException;
    import java.io.Reader;
    import java.util.List;
    
    public class CountryMapperTest extends BaseMapperTest {
        private static SqlSessionFactory sqlSessionFactory;
    
    //    @BeforeClass
    //    public static void init() {
    //        try {
                通过 Resources 工具类将 ti -config.xm 配置文件读入 Reader
    //            Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
                再通过 SqlSessionFactoryBuilder 建造类使用 Reader 创建 SqlSessionFactory工厂对象。
                在创建 SqlSessionFactory 对象的过程中
                首先解 mybatis-config.xml 配置文件，读取配置文件中的 mappers 配置后会读取全部的 Mapper xml 进行具体方法的解析，
                在这些解析完成后， SqlSessionFactory 就包含了所有的属性配置和执行 SQL 的信息。
    //            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
                使用时通过 SqlSessionFactory 工厂对象获取 splSession
    //            reader.close();
    //        } catch (IOException ignore) {
    //            ignore.printStackTrace();
    //        }
    //    }
    //
    //    private void printCountryList(List<Country> countryList) {
    //        for (Country country : countryList) {
    //            System.out.printf("%-4d%4s%4s\n", country.getId(), country.getCountryname(), country.getCountrycode());
    //        }
    //    }
    
        @Test
        public void testSelectByid() {
            SqlSession sqlSession = getSqlSession();
            try {
                UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
                SysUser user = userMapper.selectById((long) 1);
                Assert.assertNotNull(user);
                Assert.assertEquals("admin", user.getUserName());
            } finally {
                sqlSession.close();
            }
        }
    
        @Test
        public void testSelectAll() {
            SqlSession sqlSession = getSqlSession();
            try {
                UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
                List<SysUser> userList = userMapper.selectAll();
                Assert.assertNotNull(userList);
                Assert.assertTrue(userList.size() > 0);
            } finally {
                sqlSession.close();
            }
        }
    }

### 8.运行结果 ###

![88b85e9dd677412a88da04f4a8357918.png][]

### 9.总结 ###

（1）mapper接口存放在java下的mapper包里，mapper.xml存放在资源包下面！

![7abb54fe11704d47b30cd48bd7b3d0c6.png][]

namespace的值是对应的mapper接口的全限定名称

![9c4109472cc4461e910c2aaf89d0681f.png][]

（2）实体类用驼峰命名法，sql 里的映射

> 1.用别名法映射
> 
> ![550810197e4547bc95c9aebd32965b7b.png][]
> 
> 2.自动映射
> 
> 配置：
> 
> ![76cf5269ae2f45958d9f0df7d7d728f8.png][]
> 
> 3.使用 resultMap
> 
> ![279b2a14fa9a4f56bf8cb156169d462a.png][]

[63a6014bfe9a46a59caf21d5a228cb06.png]: https://img-blog.csdnimg.cn/63a6014bfe9a46a59caf21d5a228cb06.png
[c85dc6fb272a4c53a209a0ea7a5ea5b1.png]: https://img-blog.csdnimg.cn/c85dc6fb272a4c53a209a0ea7a5ea5b1.png
[88b85e9dd677412a88da04f4a8357918.png]: https://img-blog.csdnimg.cn/88b85e9dd677412a88da04f4a8357918.png
[7abb54fe11704d47b30cd48bd7b3d0c6.png]: https://img-blog.csdnimg.cn/7abb54fe11704d47b30cd48bd7b3d0c6.png
[9c4109472cc4461e910c2aaf89d0681f.png]: https://img-blog.csdnimg.cn/9c4109472cc4461e910c2aaf89d0681f.png
[550810197e4547bc95c9aebd32965b7b.png]: https://img-blog.csdnimg.cn/550810197e4547bc95c9aebd32965b7b.png
[76cf5269ae2f45958d9f0df7d7d728f8.png]: https://img-blog.csdnimg.cn/76cf5269ae2f45958d9f0df7d7d728f8.png
[279b2a14fa9a4f56bf8cb156169d462a.png]: https://img-blog.csdnimg.cn/279b2a14fa9a4f56bf8cb156169d462a.png