SpringBoot整合MyBatis-Plus

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前言

MyBatis-Plus 是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

我们的愿景是成为 MyBatis 最好的搭档，就像 魂斗罗 中的 1P、2P，基友搭配，效率翻倍。

image

特征

  • 无侵入：只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑
  • 损耗小：启动即会自动注入基本 CURD，性能基本无损耗，直接面向对象操作
  • 强大的 CRUD 操作：内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求
  • 支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错
  • 支持主键自动生成：支持多达 4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题
  • 支持 ActiveRecord 模式：支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可进行强大的 CRUD 操作
  • 支持自定义全局通用操作：支持全局通用方法注入（ Write once, use anywhere ）
  • 内置代码生成器：采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用
  • 内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于普通 List 查询
  • 分页插件支持多种数据库：支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer 等多种数据库
  • 内置性能分析插件：可输出 SQL 语句以及其执行时间，建议开发测试时启用该功能，能快速揪出慢查询
  • 内置全局拦截插件：提供全表 delete 、 update 操作智能分析阻断，也可自定义拦截规则，预防误操作

架构图

image

数据准备

本例子用的是MySQL，下面是建表语句

CREATE TABLE `user` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(128) NOT NULL DEFAULT '',
  `created_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB;

Maven 依赖

<properties>
	<mysql.version>5.1.49</mysql.version>
	<druid.version>1.1.21</druid.version>
	<mybatisplus.version>3.5.8</mybatisplus.version>
</properties>
<dependencies>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter</artifactId>
	</dependency>

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql.version}</version>
    </dependency>

    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>${druid.version}</version>
	</dependency>

	<dependency>
		<groupId>com.baomidou</groupId>
		<artifactId>mybatis-plus-spring-boot3-starter</artifactId>
		<version>${mybatisplus.version}</version>
	</dependency>
	<dependency>
		<groupId>com.baomidou</groupId>
		<artifactId>mybatis-plus</artifactId>
		<version>${mybatisplus.version}</version>
	</dependency>

</dependencies>

配置 application.properties

spring.application.name=mybatis-plus-demo
server.port=8081

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/demo?useUnicode=true&characterEncoding=UTF-8&useSSL=false&autoReconnect=true&failOverReadOnly=false
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

定义实体

package com.zxy.demo.mybatisplus.domain.entity;

import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Date;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

@TableName("user")
public class UserEntity {
    // 配置自增ID， 在create接口返回id
    @TableId(type=IdType.AUTO)
    private Long id;
    private Date createdAt;
    private String name;

    @TableField(exist = false)
    private String ignoreColumn = "ignoreColumn";

    public ZonedDateTime getCreatedDateTime() {
        return ZonedDateTime.ofInstant(this.createdAt.toInstant(), ZoneId.systemDefault());
    }

    // get set
}

定义 mapper

UserMapper.java

package com.zxy.demo.mybatisplus.domain.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.zxy.demo.mybatisplus.domain.entity.UserEntity;

// 继承BaseMapper，默认就有了基础的CRUD
public interface UserMapper extends BaseMapper<UserEntity> {
    // 自定义 SQL
    UserEntity findByName(String name);
}

user_mapper.xml

无需配置mybatis.mapper-locations=classpath*:mapper/**/*.xml， mapper文件夹放在classpath下即可，也即resources下。

<?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="com.zxy.demo.mybatisplus.domain.mapper.UserMapper">

    <select id="findByName" resultType="com.zxy.demo.mybatisplus.domain.entity.UserEntity">
        SELECT * FROM user WHERE name LIKE #{name} LIMIT 1
    </select>

</mapper>

MybatisPlusConfig.java

配置mapper的扫描，配置分页插件

package com.zxy.demo.mybatisplus;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;

@Configuration
@MapperScan("com.zxy.demo.mybatisplus.domain.mapper")
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        // 如果配置多个插件, 切记分页最后添加
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL)); 
        // 如果有多数据源可以不配具体类型, 否则都建议配上具体的 DbType
        return interceptor;
    }

}

Controller 使用

package com.zxy.demo.mybatisplus.api;

import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Scope;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.server.ResponseStatusException;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.zxy.demo.mybatisplus.domain.entity.UserEntity;
import com.zxy.demo.mybatisplus.domain.mapper.UserMapper;
import com.zxy.demo.mybatisplus.domain.service.UserService;
import com.zxy.demo.mybatisplus.dto.User;

@Controller
@Scope(ConfigurableBeanFactory.SCOPE_SINGLETON)
public class UserController {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private UserService userService;

    private UserEntity toUserEntity(User u) {
        if (null == u) {
            return null;
        }
        UserEntity userEntity = new UserEntity();
        userEntity.setId(u.id);
        userEntity.setName(u.name);
        return userEntity;
    }

    private User toUser(UserEntity userEntity) {
        if (null == userEntity) {
            return null;
        }
        User user = new User();
        user.id = userEntity.getId();
        user.name = userEntity.getName();

        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        user.createdAt = formatter.format(userEntity.getCreatedDateTime());

        return user;
    }

    @ResponseBody
    @RequestMapping(value = "/users")
    public Map users(@RequestParam long page, @RequestParam long pageSize) {
        System.out.println("users page:" + page + ", pageSize:" + pageSize);
        QueryWrapper<UserEntity> wrapper = new QueryWrapper();
        IPage<UserEntity> ret = userMapper.selectPage(new Page(page, pageSize), wrapper);
        Map m = new HashMap();
        var users = ret.getRecords().stream().map(this::toUser).collect(Collectors.toList());
        m.put("list", users);
        m.put("current 当前页", ret.getCurrent());
        m.put("pageSize 每页显示条数", ret.getSize());
        m.put("pages 总页数", ret.getPages());
        m.put("total 总条数", ret.getTotal());
        return m;
    }

    @ResponseBody
    @RequestMapping(value = "/users/{id}")
    public User getUser(@PathVariable("id") long uid) {
        var user = userMapper.selectById(uid);
        if (user == null) {
            throw new ResponseStatusException(HttpStatus.NOT_FOUND);
        }

        return toUser(user);
    }

    @ResponseBody
    @RequestMapping(value = "/users/findByName/{name}")
    public User findByName(@PathVariable("name") String name) {
        var user = userMapper.findByName(name);
        return toUser(user);
    }

    @ResponseBody
    @PostMapping(value = "/users")
    public User creatUser(@RequestBody User u) {
        UserEntity userEntity = toUserEntity(u);

        long id = userService.createUser(userEntity);
        u.id = id;

        return u;
    }

}


package com.zxy.demo.mybatisplus.domain.service.impl;

import java.util.Date;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.zxy.demo.mybatisplus.domain.entity.UserEntity;
import com.zxy.demo.mybatisplus.domain.mapper.UserMapper;
import com.zxy.demo.mybatisplus.domain.service.UserService;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public long createUser(UserEntity userEntity) {
        userEntity.setCreatedAt(new Date());
        userMapper.insert(userEntity);

        return userEntity.getId();
    }

}

问题列表

userMapper 获取不到

 Invalid bean definition with name 'userMapper' defined in file [.../userMapper.class]: Invalid value type for attribute 'factoryBeanObjectType': java.lang.String

github.com/baomidou/my…

两种解决方式，调整mybatis-spring版本或spring-boot的包

<mybatisplus.version>3.5.8</mybatisplus.version>
<mybatis.version>3.0.3</mybatis.version>

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>${mybatisplus.version}</version>
    <exclusions>
        <exclusion>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>${mybatis.version}</version>
</dependency>

<mybatisplus.version>3.5.8</mybatisplus.version>

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
    <version>${mybatisplus.version}</version>
</dependency>

mapper 自定义SQL

无需配置mybatis.mapper-locations=classpath*:mapper/**/*.xml， mapper文件夹放在classpath下即可，也即resources下。

资料

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