springboot集成mybatis-plus

文章目录

• 一、配置
• • 1、maven依赖
  • 2、配置文件application.yaml
• 二、创建过程
• • 1.创建数据库与java实体类
  • 2.mapper或dao层
  • 3.mapper.xml文件
  • 4.service层
  • 5.controller层
• 三、设置时间自动填充
• • 1.实体类日期类型设置
  • 2.自定义元对象处理器
• 四、分页查询
• • 1.配置类中创建bean
  • 2.调用分页查询的方法
• 五、多对一映射、一对多映射
• • 1.数据库表设计
  • 2.多对一映射：association
  • 3.一对多映射：collection
• 六、代码生成器
• • 1.maven依赖
  • 2.代码编写

环境：
jdk 1.8
springboot: 2.5.14

一、配置

1、maven依赖

<dependencies> <dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.2</version></dependency></dependencies> <dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency> <dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>2.5.14</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement>

2、配置文件application.yaml

#数据源配置spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://1.13.152.218:3306/mp?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghaiusername: rootpassword: zhuang123#数据库名称project:database: mysql#mybatis-plus配置mybatis-plus:configuration:#sql日志打印log-impl: org.apache.ibatis.logging.stdout.StdOutImpl#开启驼峰命名匹配map-underscore-to-camel-case: true#mapper文件mapper-locations: classpath:mapper/${project.database}/**/*.xml,classpath:mapper/*.xml#数据库实体类的包全路径，方便在mapper.xml中不许使用实体类的全路径，写类名就行（不区分大小写）type-aliases-package: com.zhuang.mp.entityglobal-config:db-config:#逻辑删除logic-delete-value: 0logic-not-delete-value: 1logic-delete-field: deleted

二、创建过程

1.创建数据库与java实体类

新建user表：

java实体类：

package com.zhuang.mp.entity;import com.baomidou.mybatisplus.annotation.*;import com.fasterxml.jackson.annotation.JsonAlias;import com.fasterxml.jackson.annotation.JsonFormat;import lombok.Builder;import lombok.Data;import org.springframework.format.annotation.DateTimeFormat;import java.time.LocalDateTime;import java.util.Date;@Data@Builder@TableName(value = "user")public class User {@TableId(type = IdType.AUTO)private Long id;@JsonAlias("user_name")private String name;@JsonAlias("user_age")private Integer age;@JsonAlias("user_email")private String email = "862627527@qq.com";@TableField(value = "create_time", fill = FieldFill.INSERT)//后端传给前端的时间格式@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")//前端传给后端的时间格式@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")@JsonAlias("create_time")private Date createTime;@JsonAlias("update_time")@TableField(value = "update_time" ,fill = FieldFill.INSERT_UPDATE)private LocalDateTime updateTime;}

2.mapper或dao层

UserMapper接口：继承BaseMapper， T为实体类User，需要加上@Mapper注解，如果不加注解需要在启动类上加@MapperScan注解

package com.zhuang.mp.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import com.zhuang.mp.entity.User;import com.zhuang.mp.entity.UserVo;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Param;import java.util.List;@Mapperpublic interface UserMapper extends BaseMapper<User> {List<User> searchByAges(@Param("ages") List<Long> ages);List<UserVo> selectBynames(@Param("names") List<String> names);}

3.mapper.xml文件

一般放在类路径下：src/main/resources/mapper/
设置命名空间 namespace
namespace=“com.zhuang.mp.mapper.UserMapper”

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.zhuang.mp.mapper.UserMapper"><resultMap id="userResultMap" type="User"><id property="id" column="id"/><result property="name" column="name"/><result property="age" column="age"/><result property="email" column="email"/><result property="createTime" column="create_time"/><result property="updateTime" column="update_time"/></resultMap><select id="searchByAges" resultType="com.zhuang.mp.entity.User">select * from user where age in<foreach collection="ages" item="age" open="(" close=")" separator=",">#{age}</foreach></select><select id="selectBynames" resultType="UserVo">select namefrom user where<foreach collection="names" item="name" separator="or">name like "%"#{name}"%"</foreach></select></mapper>

4.service层

UserService接口：需要继承IService, T 为实体类User

package com.zhuang.mp.service;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.baomidou.mybatisplus.extension.service.IService;import com.zhuang.mp.entity.User;import com.zhuang.mp.entity.UserVo;import java.util.List;/** * @program: mp * @description: * @author: mrzhuang * @create: 2022-12-15 00:48 **/public interface UserService extends IService<User> {int addUser(User user);int updateUser(User user);Page<User> searchPage(Page<User> page);List<User> searchByAges(List<Long> ages);List<UserVo> selectBynames(List<String> names);}

UsrServiceIpml实现类：需要继承ServiceImpl, M为接口UserMapper, T为实体类User，需要加上@Service注解

package com.zhuang.mp.service.impl;import com.baomidou.dynamic.datasource.annotation.DS;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;import com.zhuang.mp.entity.User;import com.zhuang.mp.entity.UserVo;import com.zhuang.mp.mapper.UserMapper;import com.zhuang.mp.service.UserService;import lombok.extern.slf4j.Slf4j;import org.springframework.stereotype.Service;import org.springframework.web.bind.annotation.RequestBody;import javax.annotation.Resource;import java.util.List;/** * @program: mp * @description: * @author: mrzhuang * @create: 2022-12-15 00:49 **/@DS("slave_1")@Service@Slf4jpublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {@Resourceprivate UserMapper userMapper;@Overridepublic int addUser(User user) {int insert = userMapper.insert(user);return insert;}@Overridepublic int updateUser(@RequestBody User user) {int update = userMapper.updateById(user);return update;}@Overridepublic Page<User> searchPage(Page<User> page) {Page<User> userPage = userMapper.selectPage(page, null);return userPage;}@Overridepublic List<User> searchByAges(List<Long> ages) {List<User> list = userMapper.searchByAges(ages);return list;}@Overridepublic List<UserVo> selectBynames(List<String> names) {return userMapper.selectBynames(names);}}

5.controller层

UserController类：

package com.zhuang.mp.controller;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.zhuang.mp.entity.User;import com.zhuang.mp.entity.UserVo;import com.zhuang.mp.enums.CodeEnum;import com.zhuang.mp.service.UserService;import com.zhuang.mp.vo.PageVo;import com.zhuang.mp.vo.ResponseVo;import io.swagger.annotations.Api;import io.swagger.annotations.ApiOperation;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.BeanUtils;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;import java.util.List;/** * @program: mp * @description: * @author: mrzhuang * @create: 2022-12-17 21:40 **/@Slf4j@Api(tags = "用户接口")@RestController@RequestMapping("/user")public class UserController {@ResourceUserService userService;@ApiOperation("用户增加")@RequestMapping("/add")public ResponseVo<User> addUser(@RequestBody User user){log.info("user: {}", user);int insert = userService.addUser(user);if (insert > 0){log.info("插入成功！");return new ResponseVo<>(CodeEnum.SUCESS.code, CodeEnum.SUCESS.message);}log.error("插入失败！");return new ResponseVo<>(CodeEnum.FAILUIRE.code, CodeEnum.FAILUIRE.message);}@RequestMapping("/update")public ResponseVo<User> updateUser(@RequestBody User user){log.info("user: {}", user);int update = userService.updateUser(user);if (update > 0){log.info("更新成功！");return new ResponseVo<>(CodeEnum.SUCESS.code, CodeEnum.SUCESS.message);}log.error("更新失败！");return new ResponseVo<>(CodeEnum.FAILUIRE.code, CodeEnum.FAILUIRE.message);}@PostMapping("/searchPage")public ResponseVo<PageVo<User>> searchPage(@RequestBody Page<User> page){Page<User> userPage = userService.searchPage(page);PageVo<User> userPageVo = new PageVo<>();BeanUtils.copyProperties(userPage, userPageVo);return new ResponseVo<>(userPageVo);}@PostMapping("/searchByAges")public ResponseVo<List<User>> searchByAges(@RequestBody List<Long> ages){List<User> list = userService.searchByAges(ages);return new ResponseVo<>(list);}@PostMapping("/searchByNames")public ResponseVo<List<UserVo>> searchByNames(@RequestBody List<String> names){List<UserVo> list = userService.selectBynames(names);return new ResponseVo<>(list);}}

三、设置时间自动填充

1.实体类日期类型设置

需要再实体类的日期属性上使用@TableField(fill = FieldFill.INSERT)
FiledFill为枚举类型

public enum FieldFill {/** * 默认不处理 */DEFAULT,/** * 插入时填充字段 */INSERT,/** * 更新时填充字段 */UPDATE,/** * 插入和更新时填充字段 */INSERT_UPDATE}

实体类：

@TableField(value = "create_time", fill = FieldFill.INSERT)//后端传给前端的时间格式@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")//前端传给后端的时间格式@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")@JsonAlias("create_time")private Date createTime;@JsonAlias("update_time")@TableField(value = "update_time" ,fill = FieldFill.INSERT_UPDATE)private LocalDateTime updateTime;

2.自定义元对象处理器

实现 MetaObjectHandler接口

package com.zhuang.mp.handler;import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;import lombok.extern.slf4j.Slf4j;import org.apache.ibatis.reflection.MetaObject;import org.springframework.stereotype.Component;import java.time.LocalDateTime;import java.util.Date;@Slf4j@Componentpublic class MyMetaObjectHandler implements MetaObjectHandler {@Overridepublic void insertFill(MetaObject metaObject) {log.info("start insert fill ....");this.strictInsertFill(metaObject, "createTime", Date.class, new Date()); // 起始版本 3.3.0(推荐使用)this.strictInsertFill(metaObject, "updateTime", Date.class, new Date()); // 起始版本 3.3.0(推荐使用)//// 或者//this.strictInsertFill(metaObject, "createTime", () -> LocalDateTime.now(), LocalDateTime.class); // 起始版本 3.3.3(推荐)//// 或者// this.fillStrategy(metaObject, "createTime", LocalDateTime.now()); // 也可以使用(3.3.0 该方法有bug)}@Overridepublic void updateFill(MetaObject metaObject) {log.info("start update fill ....");this.strictUpdateFill(metaObject, "updateTime", LocalDateTime.class, LocalDateTime.now()); // 起始版本 3.3.0(推荐)//// 或者//this.strictUpdateFill(metaObject, "updateTime", () -> LocalDateTime.now(), LocalDateTime.class); // 起始版本 3.3.3(推荐)//// 或者//this.fillStrategy(metaObject, "updateTime", LocalDateTime.now()); // 也可以使用(3.3.0 该方法有bug)}}

四、分页查询

1.配置类中创建bean

ackage com.zhuang.mp.config;import com.baomidou.mybatisplus.annotation.DbType;import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;import org.mybatis.spring.annotation.MapperScan;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class MyBatisPlusConfig {//分页查询@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor(){MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();//添加分页插件interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));return interceptor;}}

2.调用分页查询的方法

@Resourceprivate UserMapper userMapper;Page<User> userPage = userMapper.selectPage(page, null);

五、多对一映射、一对多映射

举例： 一个老师有多名学生是一对多关系，而一个学生只能有一个老师是多对一关系

1.数据库表设计

设计studen和teacher表， 两个表中的字段命名需要不一样，否则在映射过程中会有问题。

1、student表

java实体类：包含老师属性

package com.zhuang.mp.entity;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableId;import com.fasterxml.jackson.annotation.JsonInclude;import io.swagger.annotations.ApiModel;import lombok.Data;import java.io.Serializable;/** * 
 ** 
 * * @author mrzhuang * @since 2022-12-21 */@ApiModel(value = "Student对象", description = "")@Data@JsonInclude(JsonInclude.Include.NON_NULL)public class Student implements Serializable {private static final long serialVersionUID = 1L;@TableId(type = IdType.AUTO)private Integer sid;@TableField(value = "s_name")private String studentName;private Integer tid;@TableField(exist = false)private Teacher teacher;}

2、teacher表：

java实体类：

package com.zhuang.mp.entity;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableId;import com.fasterxml.jackson.annotation.JsonIgnoreProperties;import com.fasterxml.jackson.annotation.JsonInclude;import io.swagger.annotations.ApiModel;import io.swagger.annotations.ApiModelProperty;import lombok.Data;import java.io.Serializable;import java.util.List;/** * 
 ** 
 * * @author mrzhuang * @since 2022-12-21 */@ApiModel(value = "Teacher对象", description = "教师")@Data@JsonIgnoreProperties(ignoreUnknown = true)@JsonInclude(value = JsonInclude.Include.NON_NULL)public class Teacher implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty("老师id")@TableId(value = "t_id", type = IdType.AUTO)private Integer tid;@ApiModelProperty("老师姓名")@TableField(value = "t_name")private String teacherName;@ApiModelProperty("学生集合")@TableField(exist = false)private List<Student> studentList;}

2.多对一映射：association

StudentMapper.xml配置

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.zhuang.mp.mapper.StudentMapper"><resultMap id="stuResultMap" type="Student"><id property="sid" column="s_id"/><result property="studentName" column="s_name"/><result property="tid" column="t_id"/><association property="teacher" javaType="teacher"><id property="tid" column="t_id"/><result property="teacherName" column="t_name"/></association></resultMap><select id="selectByMap" resultMap="stuResultMap">select * from student s left join teacher t on s.t_id = t.t_id</select></mapper>

StudentMapper类：

package com.zhuang.mp.mapper;import com.zhuang.mp.entity.Student;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import java.util.List;/** * 
 *Mapper 接口 * 
 * * @author mrzhuang * @since 2022-12-21 */public interface StudentMapper extends BaseMapper<Student> { /** * 查询所有学生 * @return / */List<Student> selectByMap();}

StudentController:

package com.zhuang.mp.controller;import com.zhuang.mp.entity.Student;import com.zhuang.mp.service.IStudentService;import com.zhuang.mp.vo.ResponseVo;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;import java.util.List;/** * 
 *前端控制器 * 
 * * @author mrzhuang * @since 2022-12-21 */@RestController@RequestMapping("/mp/student")public class StudentController {@ResourceIStudentService studentService;@GetMapping("/selectByMap")public ResponseVo<List<Student>> selsectByMap(){/** * 查询所有学生 */List<Student> students = studentService.selectByMap();return new ResponseVo<>(students);}}

结果：

3.一对多映射：collection

TeacherMapper.xml

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.zhuang.mp.mapper.TeacherMapper"><resultMap id="techResultMap" type="teacher"><id property="tid" column="t_id"/><result property="teacherName" column="t_name"/><collection property="studentList" ofType="student"><id property="sid" column="s_id"/><result property="studentName" column="s_name"/><result property="tid" column="t_id"/></collection></resultMap><select id="selectByMap" resultMap="techResultMap">select * from teacher t right join student s on s.t_id = t.t_id</select></mapper>

TeacherMapper类：

package com.zhuang.mp.mapper;import com.zhuang.mp.entity.Teacher;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import java.util.List;/** * 
 *Mapper 接口 * 
 * * @author mrzhuang * @since 2022-12-21 */public interface TeacherMapper extends BaseMapper<Teacher> {/** * 查询全部老师 * @return */List<Teacher> selectByMap();}

TeacherController:

package com.zhuang.mp.controller;import com.zhuang.mp.entity.Teacher;import com.zhuang.mp.service.ITeacherService;import com.zhuang.mp.vo.ResponseVo;import io.swagger.annotations.Api;import io.swagger.annotations.ApiOperation;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;import java.util.List;/** * 
 *前端控制器 * 
 * * @author mrzhuang * @since 2022-12-21 */@Api(tags = "教师接口")@RestController@RequestMapping("/mp/teacher")public class TeacherController {@ResourceITeacherService teacherService;@ApiOperation("获得全部的老师")@GetMapping("searchAll")public ResponseVo<List<Teacher>> searchAll(){List<Teacher> teachers = teacherService.searchAll();return new ResponseVo<>(teachers);}@ApiOperation("一对一多映射")@GetMapping("/selectByMap")public ResponseVo<List<Teacher>> selectByMap(){List<Teacher> teachers = teacherService.selectByMap();return new ResponseVo<>(teachers);}}

结果：

六、代码生成器

1.maven依赖

<dependency><groupId>org.freemarker</groupId><artifactId>freemarker</artifactId><version>2.3.28</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId></dependency>

2.代码编写

package com.zhuang.generator;import com.baomidou.mybatisplus.generator.FastAutoGenerator;import com.baomidou.mybatisplus.generator.config.OutputFile;import com.baomidou.mybatisplus.generator.engine.FreemarkerTemplateEngine;import java.util.Collections;/** * @program: mp * @description: 逆向代码生成器 * @author: mrzhuang * @create: 2022-12-17 20:56 **/public class CodeGenerator {public static void main(String[] args) {String url = "jdbc:mysql://1.13.152.218:3306/mp" />;String username = "root";String password = "zhuang123";String author = "mrzhuang";String outputDir = "/Users/mrzhuang/Downloads/mp/generator";String parent = "com.zhuang";String moduleName = "mp";String xmlPath = "/Users/mrzhuang/Downloads/mp/generator";//String tablename = "user";FastAutoGenerator.create(url, username, password).globalConfig(builder -> {builder.author(author) // 设置作者.enableSwagger() // 开启 swagger 模式.fileOverride() // 覆盖已生成文件.outputDir(outputDir); // 指定输出目录}).packageConfig(builder -> {builder.parent(parent) // 设置父包名.moduleName(moduleName) // 设置父包模块名.pathInfo(Collections.singletonMap(OutputFile.xml, xmlPath)); // 设置mapperXml生成路径}).strategyConfig(builder -> {builder.addInclude("teacher").addInclude("student"); // 设置需要生成的表名//.addTablePrefix("t_", "c_"); // 设置过滤表前缀}).templateEngine(new FreemarkerTemplateEngine()) // 使用Freemarker引擎模板，默认的是Velocity引擎模板.execute();}}