Mybatis -- Mybatis注解开发：基本开发

Posted 2021-12-07 CodeJiao

01：Mybatis – Mybatis注解开发：基本开发
02：Mybatis – MyBatis的注解实现复杂映射开发

说明：

我在mybatis核心配置文件配置了包别名。

    <!--    别名-->
    <typeAliases>
        <package name="com.tian.pojo"/>
    </typeAliases>

我用到的依赖

pom.xml

    <dependencies>
        <!--        mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>
        <!--        mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <!--        单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
        <!--        日志打印-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

1. Mybatis注解开发

---

1.1 示例：User表基本操作

Mapper接口:

UserMapper.java

package com.itheima.mapper;

import com.itheima.domain.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserMapper {

    @Insert("insert into user values(#{id},#{username},#{password},#{birthday})")
    public void save(User user);

    @Update("update user set username=#{username},password=#{password} where id=#{id}")
    public void update(User user);

    @Delete("delete from user where id=#{id}")
    public void delete(int id);

    @Select("select * from user where id=#{id}")
    public User findById(int id);

    @Select("select * from user")
    public List<User> findAll();
}

修改MyBatis的核心配置文件

我们使用了注解替代的映射文件，所以我们只需要加载使用了注解的Mapper接口即可。

测试代码：

MyBatisTest.java

package com.itheima.test;

import com.itheima.domain.User;
import com.itheima.mapper.UserMapper;
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.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisTest {

    private UserMapper mapper;
    SqlSession sqlSession;

    @Before // 在测试方法前执行
    public void before() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        sqlSession = sqlSessionFactory.openSession(true);
        mapper = sqlSession.getMapper(UserMapper.class);
    }


    @Test
    public void testSave() {
        User user = new User();
        user.setUsername("tom");
        user.setPassword("abc");
        mapper.save(user);
    }

    @Test
    public void testUpdate() {
        User user = new User();
        user.setId(18);
        user.setUsername("lucy");
        user.setPassword("123");
        mapper.update(user);
    }

    @Test
    public void testDelete() {
        mapper.delete(18);
    }

    @Test
    public void testFindById() {
        User user = mapper.findById(2);
        System.out.println(user);
    }

    @Test
    public void testFindAll() {
        List<User> all = mapper.findAll();
        for (User user : all) {
            System.out.println(user);
        }
    }

    @After // 在测试方法后执行
    public void closeResource() {
        sqlSession.close();
    }
}

---

---