SpringBoot基础-Mybatis常用标签

准备数据

创建数据库，创建表

create database note;
use note;
CREATE TABLE `teacher` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键',
  `t_name` varchar(255) DEFAULT NULL COMMENT '姓名',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `note`.`teacher`(`id`, `t_name`) VALUES (1, '姜文');
INSERT INTO `note`.`teacher`(`id`, `t_name`) VALUES (2, '罗翔');


CREATE TABLE `student` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键',
  `s_name` varchar(255) DEFAULT NULL COMMENT '姓名',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `note`.`student`(`id`, `s_name`) VALUES (1, '张三');
INSERT INTO `note`.`student`(`id`, `s_name`) VALUES (2, '李四');
INSERT INTO `note`.`student`(`id`, `s_name`) VALUES (3, '王五');

创建SpringBoot项目

创建项目,导入相关依赖

        
            org.springframework.boot
            spring-boot-starter-freemarker
        
        
            org.springframework.boot
            spring-boot-starter-jdbc
        
        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            com.alibaba
            fastjson
            1.2.72
        
        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.2
        
        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.4
        

        
            org.springframework.boot
            spring-boot-devtools
            runtime
            true
        
        
            mysql
            mysql-connector-java
            runtime
        
        
            org.projectlombok
            lombok
            true
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
            
                
                    org.junit.vintage
                    junit-vintage-engine
                
            
        
    

配置.yml文件

mybatis:
  mapper-locations: classpath:/mybatis/**/*.xml
  type-aliases-package: com.example.note.domain
  map-underscore-to-camel-case: true
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  typeAliasesPackage: com.example.note.domain 
  mapperLocations: classpath:mybatis/**/*.xml
  global-config:
    db-config:
      id-type: auto

server:
  port: 8080
spring:
  application:
    name: note
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    name: defaultDataSource
    password: '123456789'
    url: jdbc:mysql://localhost:3306/note?serverTimezone=UTC
    username: 'root'

编写内容

1.创建test包，创建Student,Teacher类

package com.example.note.test.domain;

import lombok.Data;

@Data
public class Student {
    private Long id;
    private String sName;
}

package com.example.note.test.domain;

import lombok.Data;

@Data
public class Teacher {
    private Long id;
    private String tName;
}

2.创建mapper接口(注意添加@Mapper注解)

package com.example.note.test.mapper;

import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface TestMapper {
}

3.创建业务service接口

package com.example.note.test.service;

public interface ITestService {
}

业务service类(注意添加@Service注解)

package com.example.note.test.service.impl;

import org.springframework.stereotype.Service;

@Service
public class TestServiceImpl extends ITestService {
}

4.创建控制层controller

package com.example.note.test.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("test")
public class TestController {
}

5.在resources目录下创建mybatis/test目录，创建TestMapper.xml文件

Mybatis编写 

1.查询：,写在标签中，，id是在命名空间中唯一的标识符。resultType期望从这条语句中返回结果的类全限定名或别名，我们写的Javabean类路径或Java包装类路径。resultMap对外部 标签 的命名引用。resultType 和 resultMap 之间只能同时使用一个。用法如下(编辑TestMapper.xml):

        

     
    
        select * from student
    

编写TestMapper

package com.example.note.test.mapper;

import com.example.note.test.domain.Student;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface TestMapper {
    public List getAllStudent();
}

编写ITestService

package com.example.note.test.service;

import com.example.note.test.domain.Student;

import java.util.List;

public interface ITestService {
    public List getAllStudent();
}

编写TestServiceImpl 

package com.example.note.test.service.impl;

import com.example.note.test.domain.Student;
import com.example.note.test.mapper.TestMapper;
import com.example.note.test.service.ITestService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class TestServiceImpl implements ITestService {
    @Autowired
    private TestMapper testMapper;

    public List getAllStudent(){
        return this.testMapper.getAllStudent();
    }
}

编写TestController 

package com.example.note.test.controller;

import com.example.note.test.domain.Student;
import com.example.note.test.service.impl.TestServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("test")
public class TestController {
    @Autowired
    private TestServiceImpl testService;


    @RequestMapping("getAllStudent")
    public List getAllStudent(){
        return this.testService.getAllStudent();
    }
}

前端访问:

 

2.条件查询:条件判断语句,满足test里面的条件，执行标签里面的语句。

    
        select * from student
        
        
            where id = #{id}
        
    

3.条件查询:满足test里面的条件，执行标签里面的语句。

    
        select * from student
        
        
            
                id = #{id}
            
            
                and s_name = #{name}
            
        

    

4.插入:写在标签中，id是命名空间唯一标识符；parameterType入参类型；keyProperty指定能够唯一识别对象的属性；keyColumn设置生成键值在表中的列名；MyBatis 使用 JDBC 的 getGeneratedKeys 方法来取出由数据库内部生成的主键。

    
        insert into student (s_name) values (#{student.name})
    

5.遍历语句item是循环中的一个对象；index索引变量；collection传入的对象集合的名称；open指定开头的字符串；separator指定的集合项迭代之间的分隔符；close指定的结尾的字符串。批量插入操作如下:

    
        insert into student (s_name) values
        
           ( #{item.sName} )
        
    

6.返回最后的自增id(相当于执行 select LAST_INSERT_ID()):

    
        insert into student (s_name) values (#{student.sName} )
    

7.修改:写在标签中，id是命名空间唯一标识符；parameterType入参类型；keyProperty指定能够唯一识别对象的属性；keyColumn设置生成键值在表中的列名； MyBatis 使用 JDBC 的 getGeneratedKeys 方法来取出由数据库内部生成的主键。

    
    
       update student set s_name=#{student.sName}  where id=#{student.id}
    

8.删除:写在标签中，id是命名空间唯一标识符；parameterType入参类型。

    
    
        delete from student where id=#{id}
    

9.结果映射:,id是在命名空间中唯一的标识符。type期望从这条语句中返回结果的类全限定名或别名（Javabean类路径）。用法如下:

    
        select * from student
    
    
        
        
    

10.关联:property映射到列结果的字段或属性；javaType一个 Java 类的完全限定名，或一个类型别名。用法如下(一对一，多对一查询):

修改数据库:

CREATE TABLE `student` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键',
  `s_name` varchar(255) DEFAULT NULL COMMENT '姓名',
  `t_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8mb4;

修改Student类:

package com.example.note.test.domain;

import lombok.Data;

@Data
public class Student {
    private Long id;
    private String sName;
    private Long tId;
    private Teacher teacher;
}

编辑xml

     
    
        select * from student left join teacher on student.t_id=teacher.id
    
    
        
        
        
        
            
            
        
    

查询结果:

 

11.集合:property映射到列结果的字段或属性；ofType一个 Java 类的完全限定名，或一个类型别名。用法如下(一对多查询): 

修改Student类:

package com.example.note.test.domain;

import lombok.Data;

@Data
public class Student {
    private Long id;
    private String sName;
}

修改Teacher类:

package com.example.note.test.domain;

import lombok.Data;

import java.util.List;

@Data
public class Teacher {
    private Long id;
    private String tName;
    private List students;
}

编辑xml

    
    
        select * from teacher left join student on student.t_id=teacher.id
    
    
        
        
        
            
            
        
    

查询结果:

 

 总结

上述就是我在平时学习和SpringBoot项目里面用到的比较多的mybatis标签及他们的简单用法。