MyBatis 是一款优良的长久层框架,它反对定制化 SQL、存储过程以及高级映射。MyBatis 防止了简直所有的 JDBC 代码和手动设置参数以及获取后果集。MyBatis 能够应用简略的 XML 或注解来配置和映射原生信息,将接口和 Java 的 POJOs(Plain Ordinary Java Object,一般的 Java对象)映射成数据库中的记录。

通过注解实现数据操作

第一步:引入mysql依赖和mybatis依赖

<dependency>    <groupId>mysql</groupId>    <artifactId>mysql-connector-java</artifactId></dependency><dependency>    <groupId>org.mybatis.spring.boot</groupId>    <artifactId>mybatis-spring-boot-starter</artifactId>    <version>LATEST</version></dependency>

第二步:新建学生表及对应的实体类

CREATE TABLE `student` (   `student_id` int(30) NOT NULL AUTO_INCREMENT,   `age` int(1) DEFAULT NULL COMMENT '年龄',   `name` varchar(45) DEFAULT NULL COMMENT '姓名',   `sex` int(1) DEFAULT NULL COMMENT '性别:1:男,2:女,0:未知',   `create_time` datetime DEFAULT NULL COMMENT '创立工夫',   `status` int(1) DEFAULT NULL COMMENT '状态:1:失常,-1:删除',   PRIMARY KEY (`student_id`) ) ENGINE=InnoDB AUTO_INCREMENT=617354 DEFAULT CHARSET=utf8mb4 CHECKSUM=1 DELAY_KEY_WRITE=1 ROW_FORMAT=DYNAMIC COMMENT='学生表'
@Data@NoArgsConstructor@AllArgsConstructorpublic class Student implements Serializable {    private static final long serialVersionUID = 6712540741269055064L;    private Integer studentId;    private Integer age;    private String name;    private Integer sex;    private Date createTime;    private Integer status;}

第三步:配置数据库连贯信息

spring:  datasource:    driver-class-name: com.mysql.cj.jdbc.Driver    url: jdbc:mysql://localhost:3306/simple_fast    username: root    password: root

增删改查

@Mapperpublic interface StudentMapper {    @Select("select * from student where student_id = #{studentId}")    Student findById(@Param("studentId") Integer studentId);    @Insert("insert into student(age,name) values(#{age},#{name})")    int addStudent(@Param("name") String name,@Param("age") Integer age);    @Update("update student set name = #{name} where student_id = #{studentId}")    int updateStudent(@Param("studentId") Integer studentId,@Param("name") String name);    @Delete("delete from student where student_id = #{studentId}")    int deleteStudent(@Param("studentId") Integer studentId);}

下面演示的传参形式是通过单个参数传递的,如果想通过Map或实体类传参数,就不须要应用@Param来绑定参数了,将map中的key或者实体类中的属性与sql中的参数值对应上就能够了

通过XML配置实现数据操作

@Mapper和@MapperScan

@Mapper加在数据层接口上,将其注册到ioc容器上,@MapperScan加在启动类上,须要指定扫描的数据层接口包。如下:

@Mapperpublic interface StudentMapper {}
@SpringBootApplication@MapperScan("com.javatrip.mybatis.mapper")public class MybatisApplication {    public static void main(String[] args) {        SpringApplication.run(MybatisApplication.class, args);    }}

两个注解的作用一样,在开发中为了不便,通常咱们会应用@MapperScan。

指定mapper.xml的地位

mybatis:  mapper-locations: classpath:mybatis/*.xml

开启数据实体映射驼峰命名

mybatis:  configuration:    map-underscore-to-camel-case: true

编写xml和与之对应的mapper接口

<?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.javatrip.mybatis.mapper.StudentXMapper">    <select id="findById" resultType="com.javatrip.mybatis.entity.Student">        select * from student where student_id = #{studentId}    </select>    <insert id="addStudent" parameterType="com.javatrip.mybatis.entity.Student">        insert into student(name,age) values(#{name},#{age})    </insert>        <update id="updateStudent" parameterType="com.javatrip.mybatis.entity.Student">        update student set name = #{name} where  student_id = #{studentId}    </update>    <delete id="deleteStudent" parameterType="Integer">        delete from student where student_id = #{studentId}    </delete></mapper>
@Mapperpublic interface StudentXMapper {    Student findById(@Param("studentId") Integer studentId);    int addStudent(Student student);    int updateStudent(@Param("studentId") Integer studentId,@Param("name") String name);    int deleteStudent(@Param("studentId") Integer studentId);}

编写测试类

@SpringBootTestclass MybatisApplicationTests {    @Autowired    StudentMapper mapper;    @Autowired    StudentXMapper xMapper;    @Test    void testMapper() {        Student student = mapper.findById(10);        mapper.addStudent("Java旅途",19);        mapper.deleteStudent(31);        mapper.updateStudent(10,"Java旅途");    }    @Test    void contextLoads() {                Student student = xMapper.findById(10);        Student studentDo = new Student();        studentDo.setAge(18);        studentDo.setName("Java旅途呀");        xMapper.addStudent(studentDo);        xMapper.deleteStudent(32);        xMapper.updateStudent(31,"Java旅途");    }}

这里有几个须要留神的点:mapper标签中namespace属性对应的是mapper接口;select标签的id对应mapper接口中的办法名字;select标签的resultType对应查问的实体类,应用全门路。

此是spring-boot-route系列的第八篇文章,这个系列的文章都比较简单,次要目标就是为了帮忙首次接触Spring Boot 的同学有一个零碎的意识。本文已收录至我的github,欢送各位小伙伴star

github:https://github.com/binzh303/s...

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