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