springboot + mybatisPlus 入门实例

上一篇 / 下一篇  2020-08-18 10:12:51

  使用mybatisPlus的优势
  集成mybatisplus后,简单的CRUD就不用写了,如果没有特别的sql,就可以不用mapper的xml文件。
  项目搭建前提条件
  1、IDEA,并且已安装lombok插件
  2、mysql数据库,本实例采用mysql8.0版本,与mysql5.x版本有些不一样,如果使用mysql5.x,只需要修改相应的配置即可。
  1. 导入相关依赖
  如果项目中有mybatis依赖可以直接删除了,mybatisPlus里包含了mybatis的依赖
  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <!-- mybatisPlus -->
  <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus-boot-starter</artifactId>
      <version>3.3.2</version>
  </dependency>
  <!-- mysql 5.x驱动 -->
  <!--<dependency>
           <groupId>mysql</groupId>
           <artifactId>mysql-connector-java</artifactId>
           <version>5.1.39</version>
  </dependency>-->
  <!-- mysql8.0 驱动 -->
  <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.20</version>
  </dependency>
  <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.21</version>
  </dependency>
  <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
  </dependency>
  2. yml 配置
  server:
    port: 8080
    servlet:
      context-path: /
    tomcat:
      uri-encoding: UTF-8
  spring:
    datasource:
      # mysql5.x 配置,高版本需要加useSSL=false
      #url: jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
      # mysql8.0 需要加&useSSL=false&serverTimezone=UTC
      url: jdbc:mysql://localhost:3306/test?zeroDateTimeBehavior=convertToNull&characterEncoding=utf8&useSSL=false&serverTimezone=UTC
      username: root
      password: 123456
      # mysql8.0 驱动
      driver-class-name: com.mysql.cj.jdbc.Driver
      # mysql5.x 驱动
      #driver-class-name: com.mysql.jdbc.Driver
      debug: false
      #Druid#
      name: test
      type: com.alibaba.druid.pool.DruidDataSource
      filters: stat
      maxActive: 20
      initialSize: 1
      maxWait: 60000
      minIdle: 1
      timeBetweenEvictionRunsMillis: 60000
      minEvictableIdleTimeMillis: 300000
      validationQuery: select 'x'
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      poolPreparedStatements: true
      maxOpenPreparedStatements: 20
  #-----------------------------------------------------
  # pom.xml引用 mybatis-plus包,需要这样配置
  #mybatis:
  #  type-aliases-package: com.example.demo.model
  #  mapper-locations: classpath:mybatis/mappers/*.xml
  #  configuration:
  #    map-underscore-to-camel-case: true
  #-----------------------------------------------------
  #-----------------------------------------------------
  # pom.xml引用 mybatis-plus-boot-starter包,需要这样配置
  mybatis-plus:
    type-aliases-package: com.example.demo.model
    mapper-locations: classpath:mybatis/mappers/*.xml
    configuration:
      map-underscore-to-camel-case: true
  #-----------------------------------------------------
  3. 代码
  User类
  @TableId(type = IdType.AUTO) 表示我们使用自增主键
  import com.baomidou.mybatisplus.annotation.IdType;
  import com.baomidou.mybatisplus.annotation.TableField;
  import com.baomidou.mybatisplus.annotation.TableId;
  import com.baomidou.mybatisplus.annotation.TableName;
  import lombok.Data;
  import lombok.ToString;
  import java.util.Date;
  @Data
  @ToString
  @TableName("user_demo")
  public class User {
      @TableId(type = IdType.AUTO)
      private Integer id;
      @TableField("name")
      private String name;
      @TableField("password")
      private String password;
      @TableField("age")
      private Integer age;
      @TableField("email")
      private String email;
      /**
       * 注意:此处如果不加 @TableField注解,mybatisPlus会默认将createTime映射成 create_time字段
       * 由于数据库字段为createTime,所以需要指定
       */
      @TableField("createTime")
      private Date createTime;
  }
  mapper类
  继承BaseMapper就可以,会把一些crud的操作帮我们自动生成注入。
  import com.baomidou.mybatisplus.core.mapper.BaseMapper;
  import com.example.demo.model.User;
  public interface UserMapper extends BaseMapper<User> {
      public User findUserByName(String name);
  }
  Controller类
  import com.example.demo.mapper.UserMapper;
  import com.example.demo.model.User;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.web.bind.annotation.GetMapping;
  import org.springframework.web.bind.annotation.PathVariable;
  import org.springframework.web.bind.annotation.RequestMapping;
  import org.springframework.web.bind.annotation.RestController;
  @RestController
  @RequestMapping("/user")
  public class UserController {
      @Autowired
      private UserMapper userMapper;
      /**
       * 根据ID查找
       * @param id
       * @return
       */
      @GetMapping("/get/{id}")
      public String getUserById(@PathVariable String id){
          User user = userMapper.selectById(id);
          return "hello " + user.getName();
      }
      /**
       * 根据name查找
       * @param name
       * @return
       */
      @GetMapping("/name/{name}")
      public String getUserByName(@PathVariable String name){
          User user = userMapper.findUserByName(name);
          return "getUserByName " + user.getName();
      }
  }
  UserMapper.xml
  <?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.example.demo.mapper.UserMapper">
      <resultMap id="userResultMap" type="com.example.demo.model.User" >
          <id column="id" property="id"  />
          <result column="name" property="name" />
          <result column="password" property="password"  />
          <result column="age" property="age"  />
          <result column="email" property="email"  />
          <result column="createTime" property="createTime"  />
      </resultMap>
      <select id="findUserByName" resultMap="userResultMap">
          SELECT
          id,
          name,
          password,
          age,
          email,
          createTime
          FROM user_demo
          where name = #{name}
      </select>
  </mapper>
  实例运行效果
  浏览器输入:http://localhost:8080/user/name/aaa

TAG: 软件开发 java Java

 

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  • 建立时间: 2020-08-11
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