自学springboot之整合mybatis

springboot整合mybatis

1. 新建一个项目，记得勾选web、sql相关java

2. 额外导入两个依赖mysql

   <!--mybatis-springboot-->
   <dependency>
       <groupId>org.mybatis.spring.boot</groupId>
       <artifactId>mybatis-spring-boot-starter</artifactId>
       <version>2.1.1</version>
   </dependency>
   <!--lombok-->
   <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
       <version>1.18.12</version>
       <scope>provided</scope>
   </dependency>

3. 配置数据源web

   spring.datasource.username=root
   spring.datasource.password=1227
   spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
   spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
   # 别名
   mybatis.type-aliases-package=com.ryan.pojo

4. 链接数据库spring

5. 编写pojo类sql

   package com.ryan.pojo;
   
   import lombok.AllArgsConstructor;
   import lombok.Data;
   import lombok.NoArgsConstructor;
   
   @Data
   @AllArgsConstructor
   @NoArgsConstructor
   public class User {
   
       private int id;
       private String username;
       private String gender;
       private String address;
   
   }

6. 编写mapper接口，并添加@Mapper注解数据库

   package com.ryan.mapper;
   
   import com.ryan.pojo.User;
   import org.apache.ibatis.annotations.*;
   import org.springframework.stereotype.Component;
   
   import java.util.List;
   //使用 @Mapper，最终 Mybatis 会有一个拦截器，会自动的把 @Mapper 注解的接口生成动态代理类。
   // 这点能够在 MapperRegistry 类中的源代码中查看。
   //@Mapper 注解针对的是一个一个的类，至关因而一个一个 Mapper.xml 文件。
   // 若是一个接口一个接口的使用 @Mapper，太麻烦了，因而 @MapperScan 就应用而生了。能够在application类中使用
   // @MapperScan 配置一个或多个包路径，自动的扫描这些包路径下的类，自动的为它们生成代理类。
   @Mapper//通常都是使用在接口上
   public interface UserMapper {
       @Select("select * from mybatis.user")
       List<User> queryUserList();
       @Select("select * from mybatis.user where id = #{id}")
       User queryUserById(@Param("id") int id);
       @Insert("insert into user(id,username,gender,address) values(#{id},#{username},#{gender},#{address})")
       int addUser(User user);
       @Delete("delete from mybatis.user where id = #{id}")
       int deleteUserById(@Param("id") int id);
       @Update("update mybatis.user set username=#{username},address=#{address} where id=#{id}")
       int updateUser(User user);
   }

7. 编写service层apache

   package com.ryan.serviece;
   
   import com.ryan.pojo.User;
   import org.apache.ibatis.annotations.*;
   
   import java.util.List;
   
   public interface UserService {
       List<User> queryUserList();
       User queryUserById(int id);
       int addUser(User user);
       int deleteUserById(int id);
       int updateUser(User user);
   }

   package com.ryan.serviece;
   
   import com.ryan.mapper.UserMapper;
   import com.ryan.pojo.User;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.stereotype.Service;
   
   import java.util.List;
   
   @Service
   public class UserServiceImpl implements UserService {
   
       @Autowired
       private UserMapper userMapper;//此处报错，程序自己没有问题，是idea的问题
   
       public void setUserMapper(UserMapper userMapper) {
           this.userMapper = userMapper;
       }
   
       @Override
       public List<User> queryUserList() {
           return userMapper.queryUserList();
       }
   
       @Override
       public User queryUserById(int id) {
           return userMapper.queryUserById(id);
       }
   
       @Override
       public int addUser(User user) {
           return userMapper.addUser(user);
       }
   
       @Override
       public int deleteUserById(int id) {
           return userMapper.deleteUserById(id);
       }
   
       @Override
       public int updateUser(User user) {
           return userMapper.updateUser(user);
       }
   }

8. 编写controller层springboot

   package com.ryan.controller;
   
   import com.ryan.pojo.User;
   import com.ryan.serviece.UserServiceImpl;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.PathVariable;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   import java.util.List;
   
   @RestController
   public class UserController {
   
       @Autowired
       private UserServiceImpl userService;
   
       @RequestMapping("/queryUserList")
       public List<User> queryUserList(){
           List<User> users = userService.queryUserList();
           return users;
       }
   
       @RequestMapping("/queryUserById/{id}")
       public User queryUserById(@PathVariable("id") int id){
           User user = userService.queryUserById(id);
           return user;
       }
   
       @RequestMapping("/addUser")
       public String addUser(User user){
           user.setId(11);
           user.setUsername("ryan222");
           user.setGender("男");
           user.setAddress("天河");
           userService.addUser(user);
           return "insert ok";
       }
   
       @RequestMapping("/deleteUserById/{id}")
       public String deleteUserById(@PathVariable("id") int id){
           userService.deleteUserById(id);
           return "delete ok";
       }
   
       @RequestMapping("/updateUser")
       public String updateUser(User user){
           user.setId(8);
           user.setUsername("ryan1111");
           user.setAddress("shanghai");
           userService.updateUser(user);
           return "update ok";
       }
   }

9. 测试：略mybatis

注意点：app

• 整和mybatis时，别忘了导入mybatis提供的启动器（依赖）
• 别忘了配置数据源，同时能够经过mybatis.配置相关mybatis
• 写mapper接口时别忘了加上注解@Mapper
• 写serviece层时自动装配可能会出现报错：Could not autowire. No beans of ‘UserMapper’ type found.，能够忽略，程序可正常运行，可能属于idea的bug

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