分类： Mybatis

一、添加mybatis和数据库驱动依赖

        <!--添加mybatis依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.3.0</version>
        </dependency>
        <!--添加mysql驱动依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>

二、在pom.xml指定mapper路径保护到classpath中去。

       <!--  resouce插件  -->
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                     <include>**/*.*</include>
                </includes>
            </resource>
        </resources>

三、创建实体类

public class User {

    private Integer id;
    private String type;
    private String name;
    private String description;


    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", type='" + type + '\'' +
                ", name='" + name + '\'' +
                ", description='" + description + '\'' +
                '}';
    }
}

四、创建Dao接口，并定义业务方法。

import com.jishuge.app01.model.User;
import org.apache.ibatis.annotations.Mapper;

import javax.websocket.server.PathParam;


/**
 * @Mapper：告诉Mybatis这是dao接口，创建该接口的代理对象。
 */
@Mapper
public interface UserDao {

    User selectById(@PathParam("id") Integer id);

}

五、在mapper中创建对应的xml文件，写sql语句

<?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">

<!--指定是那个Dao文件接口。-->
<mapper namespace="com.jishuge.app01.dao.UserDao">
    <!--id应该是方法名称，这样可以保持唯一性-->
    <!--    #{id}  就是传入的方法参数  -->
    <select id="selectById" resultType="com.jishuge.app01.model.User">
        select * from user where id= #{id};
    </select>
</mapper>

六、创建Service层对象，创建Service接口和实现类，调用Dao对象方法。

//创建Service接口
public interface UserService {

    public User queryUser(Integer id);

}



//实现Service接口
/**
 * 一定要加入这个@service,声明为业务层对象。
 */
@Service
public class UserServiceImpl implements UserService {

    /**
     * 自动注入
     */
    @Autowired
    private UserDao userDao;

    @Override
    public User queryUser(Integer id) {
        return userDao.selectById(id);
    }
}

七、创建controller对象访问Service

@Controller
public class BootController {

    @Autowired
    private UserService userService;

    @RequestMapping("/user/info")
    @ResponseBody
    public String getUserInfo(Integer id) {
        User user = userService.queryUser(id);
        return user.toString();
    }

}

八、在application.yml文件配置数据库链接信息。

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=PRC
    password: root
    username: root
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #日志配置，输出到控制台
  mapper-locations: classpath:mapper/*.xml #指定mapper文件地址