MyBatis-Getting Started-Quick Start Program

The use of the MyBatis framework this time is based on the SpringBoot framework. Create a SpringBBot project in IDEA and select the corresponding dependencies according to your needs.

quick start

• Requirement: Use MyBatis to query all user data
• step:
  • Preparations (create Spring Boot project, database user table, entity class User)
    • Entity class objects are used to encapsulate results from data
  • Refer to the relevant dependencies of MyBatis, configure MyBatis (configure the database information to establish a connection: database driver, URL of the database connection (including information such as the address of the database, port number and database name), database user name and password)
    • Configure the mybatis instance as follows:
      • 
    • In the SpringBoot project, the configuration information is stored in the application.properties file
    • Reference related dependencies:
    • When you choose to use the Maven mode when creating a SpingBoot project, the dependency information is saved in the pom.xml file

      • <?xml version="1.0" encoding="UTF-8"?>
        <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>3.1.2</version>
                <relativePath/> <!-- lookup parent from repository -->
            </parent>
        
            <!-- Generated by https://start.springboot.io -->
            <!-- 优质的 spring/boot/data/security/cloud 框架中文文档尽在 => https://springdoc.cn -->
        
            <groupId>com.example</groupId>
            <artifactId>springboot-mybatis</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <name>springboot-mybatis</name>
            <description>springboot-mybatis</description>
            <properties>
                <java.version>20</java.version>
            </properties>
        
            <dependencies>
                <!--        mybatis的起步依赖-->
                <dependency>
                    <groupId>org.mybatis.spring.boot</groupId>
                    <artifactId>mybatis-spring-boot-starter</artifactId>
                    <version>3.0.2</version>
                </dependency>
                <!--mysql的驱动包-->
                <dependency>
                    <groupId>com.mysql</groupId>
                    <artifactId>mysql-connector-j</artifactId>
                    <scope>runtime</scope>
                </dependency>
                <!--        springboot项目单元测试的依赖-->
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-test</artifactId>
                    <scope>test</scope>
                </dependency>
                <dependency>
                    <groupId>org.mybatis.spring.boot</groupId>
                    <artifactId>mybatis-spring-boot-starter-test</artifactId>
                    <version>3.0.2</version>
                    <scope>test</scope>
                </dependency>
            </dependencies>
        
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-maven-plugin</artifactId>
                    </plugin>
                </plugins>
            </build>
        
        </project>
        

  • Write SQL statement (annotation\XML)
    • The persistence layer in MyBatis generally contains the name of Mapper, which is the same as the Dao layer in the three-tier architecture. Specific examples:

      • package com.example.mapper;
        
        import com.example.pojo.User;
        import org.apache.ibatis.annotations.Mapper;
        import org.apache.ibatis.annotations.Select;
        
        import java.util.List;
        
        @Mapper// 在运行时，会自动生成该接口的实现类对象（代理对象），并且SpringBoot框架会将该对象交给IOC容器管理,称为IOC容器中的bean了，可以通过依赖注入的方式进行嗲用
        public interface UserMapper {
            @Select("select * from user")
            public List<User> list();
        }