0 Mybatis的简单介绍
MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。2013年11月迁移到Github。
iBATIS一词来源于“internet”和“abatis”的组合，是一个基于Java的持久层框架。iBATIS提供的持久层框架包括SQL Maps和Data Access Objects（DAOs）
MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 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,普通的 Java对象)映射成数据库中的记录。
思想：ORM:Object Relational Mapping
Mybatis基本框架：
1 环境搭建
新建Spring Boot项目，引入依赖
pom.xml
<!--mysql--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.47</version> </dependency> <!--mybatis--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.2</version> </dependency> <!--Druid数据源--> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.9</version> </dependency> <!--测试--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency>
DB-sql
CREATE TABLE `student` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) DEFAULT NULL, `age` int(11) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=utf8;
项目结构
2 整合方式一：注解版
2.1 配置
server: port: 8081 spring: datasource: # 配置数据库 username: root password: 12345 driver-class-name: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/test #数据库名 type: com.alibaba.druid.pool.DruidDataSource
2.2 编码
/** * 注解版 */ @Mapper @Repository public interface JavaStudentMapper { /** * 添加一个学生 * * @param student * @return */ @Insert("insert into student(name, age) " + "values (#{name}, #{age})") public int saveStudent(Student student); /** * 根据ID查看一名学生 * * @param id * @return */ @Select("select * " + "from student " + "where id = #{id}") public Student findStudentById(Integer id); /** * 查询全部学生 * * @return */ @Select("select * " + "from student") @Results({ @Result(property = "id", column = "id"), @Result(property = "name", column = "name"), @Result(property = "age", column = "age") }) public List<Student> findAllStudent(); /** * 根据ID删除一个 * * @param id * @return */ @Delete("delete " + "from student " + "where id = #{id}") public int removeStudentById(Integer id); /** * 根据ID修改 * * @param student * @return */ @Update("update set name=#{name},age=#{age} " + "where id=#{id}") public int updateStudentById(Student student); }
2.3 测试
@Autowired private JavaStudentMapper studentMapper; @Test void testJavaMapperInsert() { Student student = new Student("张三", 22); System.out.println(studentMapper.saveStudent(student)); } @Test void testJavaMapperFind() { System.out.println(studentMapper.findStudentById(2)); } @Test void testJavaMapperFindAll() { System.out.println(studentMapper.findAllStudent()); } @Test void testJavaMapperUpdate() { Student student = new Student(2, "张三", 22); System.out.println(studentMapper.updateStudentById(student)); } @Test void testJavaMapperDelete() { System.out.println(studentMapper.removeStudentById(2)); }
3 整合方式二：XML版
3.1 配置
server: port: 8081 spring: application: name: hospitalManager #项目名 datasource: # 配置数据库 username: root password: 12345 driver-class-name: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/test #数据库名 type: com.alibaba.druid.pool.DruidDataSource mybatis: mapper-locations: classpath:mapper/*Mapper.xml #扫描resources下的mapper文件夹下的xml文件 type-aliases-package: org.ymx.sp_mybatis.pojo #实体类所在包，定义别名
主启动类：
@SpringBootApplication @MapperScan("org.ymx.sp_mybatis.xmlMapper") //扫描的mapper public class SpMybatisApplication { public static void main(String[] args) { SpringApplication.run(SpMybatisApplication.class, args); } }
3.2 编码
/** * xml版 */ @Mapper @Repository public interface XmlStudentMapper { /** * 添加一个学生 * * @param student * @return */ public int saveStudent(Student student); /** * 根据ID查看一名学生 * * @param id * @return */ public Student findStudentById(Integer id); /** * 查询全部学生 * * @return */ public List<Student> findAllStudent(); /** * 根据ID删除一个 * * @param id * @return */ public int removeStudentById(Integer id); /** * 根据ID修改 * * @param student * @return */ public int updateStudentById(Student student); }
xml文件（StudentMapper.xml）
<?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="org.ymx.sp_mybatis.dao.xmlMapper.XmlStudentMapper"> <!-- 添加学生--> <insert id="saveStudent" parameterType="org.ymx.sp_mybatis.pojo.Student" useGeneratedKeys="true" keyProperty="id"> insert into student(name, age) values (#{name}, #{age}) </insert> <!--查看学生根据ID--> <select id="findStudentById" parameterType="integer" resultType="org.ymx.sp_mybatis.pojo.Student"> select * from student where id = #{id} </select> <!--查看全部学生--> <select id="findAllStudent" resultMap="studentResult"> select * from student </select> <!--删除学生根据ID--> <delete id="removeStudentById" parameterType="integer"> delete from student where id = #{id} </delete> <!--修改学生根据ID--> <update id="updateStudentById" parameterType="org.ymx.sp_mybatis.pojo.Student"> update student set name=#{name}, age=#{age} where id = #{id} </update> <!--查询结果集--> <resultMap id="studentResult" type="org.ymx.sp_mybatis.pojo.Student"> <result column="id" javaType="INTEGER" jdbcType="INTEGER" property="id"/> <result column="name" javaType="STRING" jdbcType="VARCHAR" property="name"/> <result column="age" javaType="INTEGER" jdbcType="INTEGER" property="age"/> </resultMap> </mapper>
3.3 测试
@Autowired private XmlStudentMapper studentMapper; @Test void testJavaMapperInsert() { Student student = new Student("张三", 22); System.out.println(studentMapper.saveStudent(student)); } @Test void testJavaMapperFind() { System.out.println(studentMapper.findStudentById(2)); } @Test void testJavaMapperFindAll() { System.out.println(studentMapper.findAllStudent()); } @Test void testJavaMapperUpdate() { Student student = new Student(2, "张三", 22); System.out.println(studentMapper.updateStudentById(student)); } @Test void testJavaMapperDelete() { System.out.println(studentMapper.removeStudentById(2)); }
4 总结
基本步骤：
注意事项：
（1）相比注解方式，更推荐使用xml方式，因为注解方式将SQL语句嵌套到Java代码中，一旦需要修改则需要重新编译项目，而xml方式则不需要重新编译项目
（2）xml方式需要在主启动函数或配置类中配置接口的扫描路径
