SpringBoot集成MyBatis或者MyBatis-plus的MVC的三层架构

mybatis的三层架构书写

mybatis-plus的三层架构书写

举个栗子 ​

mybatis-plus使用分页插件

mybatis-plus中集成了import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

下面举例一个条件查询

引入依赖

<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>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.6.2version>
        <relativePath/> 
    parent>
    <groupId>cc.soufflegroupId>
    <artifactId>mybatis_plus_caseartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>mybatis_plus_casename>
    <properties>
        <java.version>1.8java.version>
    properties>
    <dependencies>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        
        <dependency>
            <groupId>com.baomidougroupId>
            <artifactId>mybatis-plus-boot-starterartifactId>
            <version>3.4.2version>
        dependency>
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <scope>runtimescope>
        dependency>
        
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

    
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombokgroupId>
                            <artifactId>lombokartifactId>
                        exclude>
                    excludes>
                configuration>
            plugin>
        plugins>
    build>

project>

三层架构的实现

根据mybatis-plus自动生成的三层架构进行实现

进行数据库的指定

,在分页的操作中, 因为不同的数据库的拼接语句不一样所有需要指定数据库类型

@Configuration
public class MpConfig {
    /**
     * 配置MP 分页插件MybatisPlusInterceptor
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        //指定数据库类型, 这样配置之后, 会自动拼接limit这个关键字语句  ;  因为不同的数据看的拼接语句不一样所有需要指定数据库类型
        PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor(DbType.MYSQL);
        mybatisPlusInterceptor.addInnerInterceptor(paginationInnerInterceptor);


        return mybatisPlusInterceptor;
    }
}

测试操作

    //条件查询：根据姓名、性别、出生年月组合条件进行查询  select * from user where user_name like "%周%" and user_sex=0  and user_birthday  between ? and ?
    //思考：根据条件查询，那么查询的list对象是null还是元素为size=0
    @Test
    void selectByQueryWrapper() {
        //姓名
        String userName = "周";
        //性别
        Integer userSex = null;
        //出生年月最小值
        LocalDate userBirthDayMin = null;
        //出生年月最大值
        LocalDate userBirthDayMax = null;

        //根据以上4个变量来动态拼接SQL, 定义查询条件
        QueryWrapper<User> userQueryWrapper = new QueryWrapper<>();
        //这里的Right 表示的是 百分号% 位置, 右边就是指定为放在右边数据的右边, 即 周%
        userQueryWrapper.likeLeft(StringUtils.isNotBlank(userName),"user_name","周");
        userQueryWrapper.eq(userSex != null,"user_sex",0);
        userQueryWrapper.between(((userBirthDayMin !=null ) && (userBirthDayMax != null)),"user_birthday","2020-01-01","2010-11-05");
        // 第一个参数current: 表示需要第几页的数据, 第二个参数size,  表示一页多少个数据
        Page<User> userPage = new Page<>(1,4);
        Page<User> userPageData = userMapper.selectPage(userPage, userQueryWrapper);
        
        //数据需要进行单独的获取
        List<User> records = userPageData.getRecords();
        System.out.println(records);
        records.forEach(user -> System.out.println("user = " + user));


    }

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