Mybatis实现增删改查

下面是详细讲解MyBatis实现增删改查的完整攻略:

1.添加MyBatis配置文件

在项目下创建mybatis-config.xml配置文件，其中包含对mybatis初始化相关配置信息，如数据源、别名、 mapper扫描等。

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTDConfig3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-config.dtd">
<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://localhost:3306/mybatis_test?useUnicode=true&amp;characterEncoding=UTF8" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/example/mapper/DeptMapper.xml"/>
    </mappers>
</configuration>

2.添加映射文件

在resources文件夹下创建com/example/mapper/DeptMapper.xml文件，其中定义了具体的CRUD操作(例如:增删改查等)，如下示例所示:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.mapper.DeptMapper">

    <!-- 根据id查询部门 -->
    <select id="getDeptById" parameterType="long" resultType="com.example.entity.Dept">
        select * from dept where id=#{id}
    </select>

    <!-- 新增部门 -->
    <insert id="addDept" parameterType="com.example.entity.Dept">
        insert into dept(name,address) values(#{name},#{address})
    </insert>

    <!-- 更新部门 -->
    <update id="updateDept" parameterType="com.example.entity.Dept">
        update dept set name=#{name},address=#{address} where id=#{id}
    </update>

    <!-- 删除部门 -->
    <delete id="deleteDeptById" parameterType="long">
        delete from dept where id=#{id}
    </delete>

</mapper>

3.添加实体类

public class Dept {
    private Long id;
    private String name;
    private String address;
    //getter and setter method
}

4.添加Mapper接口

public interface DeptMapper {
    // 根据id查询部门
    Dept getDeptById(Long id);

    // 新增部门
    int addDept(Dept dept);

    // 更新部门
    int updateDept(Dept dept);

    // 删除部门
    int deleteDeptById(Long id);
}

5. MyBatis映射接口和SQL语句的绑定

在applicationContext.xml文件中，配置mybatis的MapperScannerConfigurer，例如:

<!-- 扫描Mapper接口 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.example.mapper"/>
</bean>

6. 测试

//获取Spring上下文
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
//获取Mapper
DeptMapper deptMapper = applicationContext.getBean(DeptMapper.class);

//查询
Dept dept = deptMapper.getDeptById(1L);
System.out.println(dept);

//新增
Dept dept1 = new Dept();
dept1.setName("test-1");
dept1.setAddress("address-1");
int addDept = deptMapper.addDept(dept1);
System.out.println(addDept);

//更新
dept.setAddress("updated-address");
int updateDept = deptMapper.updateDept(dept);
System.out.println(updateDept);

//删除
int deleteDept = deptMapper.deleteDeptById(1L);
System.out.println(deleteDept);