【Springboot入门Ⅴ.Ⅱ】Mybatis使用(使用maven jar 项目)

本文链接：https://blog.youkuaiyun.com/qq_40790042/article/details/98114240

使用maven-jar项目讲解

pom.xml加入依赖

<dependencies>
  
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</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>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.11</version>
    <scope>test</scope>
  </dependency>

  <dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.1.1</version>
  </dependency>

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

配置数据源文件

spring.datasource.url=jdbc:mysql://localhost:3306/soft_test?serverTimezone=Asia/Shanghai&useUnicode=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=admin
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

1.(注解配置mybatis)创建一个mapper

建议使用注解,sql语句有两种写法,当字段名字和参数名字不一样或者前后顺序不一样时则需要使用@Param注解指定参数,以下两种均可使用 [更正]

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;

public interface UserMapper {

    @Insert("insert into tester(username,password) values (#{0},#{1})")
    int save(String username,String password);

/*@Insert("insert into tester(username,password) values (#{username},#{password})")
    int save(@Param("username") String username,@Param("password") String password);*/
}

Service

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public void register(String username, String password) {
        userMapper.save(username,password);
    }

}

Controller

@Controller   //如果要访问freemarker模板就不需要写@RestController
@RequestMapping("user")   //设置访问路径
public class UserController {

    @Autowired
    UserServiceImpl service;

    @RequestMapping("register")
    @ResponseBody
    public String register(){
        service.register("gll","456");
        return "success";
    }

}

App

新增两个注解,@MapperScan用于扫描Mapper类,@EnableAutoConfiguration用于自动配置类

2.使用xml配置mybatis

Xml编写

位置可以放在mapper接口位置

<?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="stu.gll.mapper.UserMapper" >

    <insert id="save">
        insert into user (username,password) VALUES(#{0},#{1})
    </insert>
    <select id="findByUsername" resultType="stu.gll.model.User" parameterType="string">
        select * from t_user where username = #{username,jdbcType=VARCHAR}
    </select>
</mapper>

使用xml时,我们mapper接口就不需要使用注解

public interface UserMapper {

    //@Insert("insert into tester(username,password) values (#{0},#{1})")
    int save(String username,String password);

    User findByUsername(String username);

    /*@Insert("insert into tester(username,password) values (#{username},#{password})")
    int save(@Param("username") String username,@Param("password") String password);*/
}

Service添加方法

Controller

Pom.xml导入新配置

注意这里需要在pom.xml中添加下面代码

<build>
  <resources>
    <resource>
      <directory>src/main/java</directory>
      <includes>
        <include>**/*.xml</include>
      </includes>
    </resource>
  </resources>
</build>

没有加入上面配置会出错[org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): stu.gll.mapper.UserMapper.findByUsername],前面我们设置异常处理类,把那个类的方法注释了才能看到该错误