SpringBoot集成MyBatis查询数据库

红太狼 2023-05-29 02:28 79阅读 0赞

### 代码已上传，[GitHub地址][GitHub] ###

准备数据库：  
![在这里插入图片描述][20191101145146949.png]

1.  配置maven仓库

<dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-jdbc</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.0</version>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
                <scope>provided</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
            
            <dependency>
                <groupId>com.google.code.gson</groupId>
                <artifactId>gson</artifactId>
                <version>2.8.5</version>
            </dependency>

1.  application.properties中添加mybatis映射文件配置  
    `这一步是配置xml文件的位置，如果不配置，找不到xml映射文件`

#配置mybatis #指定sql映射文件位置 claspath:resources文件夹
    mybatis.mapper-locations=classpath:mapper/*.xml

1.  添加映射对象dao

public class User { 
        private int id;
        private String head_pic;
        private String user_name;
        private String account;
        private String pw;
        @Override
        public String toString() { 
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("account",account);
            jsonObject.put("pw",pw);
            return jsonObject.toString();
        }
        //getters...
        //setters...
    }

1.  添加关联映射对象的java类  
    `@Repository可以换成@Mapper`

@Repository//映射mapper文件，替代@mapper
    public interface UserMapper { 
        User Sel(int id);
    }

1.  添加数据service

@Service//service标识
    public class UserService { 
        @Autowired//自动初始化对象
        UserMapper userMapper;
        public User Sel(int id){ 
            return userMapper.Sel(id);
        }
    }

1.  添加控制器controller

`注意写法，get请求参数不需要配置，如果配置成/getUser/{id}这种形式，浏览器会报错`

> Whitelabel Error Page  
> This application has no explicit mapping for /error, so you are seeing this as a fallback.  
> Fri Nov 01 14:56:52 CST 2019  
> There was an unexpected error (type=Not Found, status=404).  
> No message available

@RestController//controller标识
    @RequestMapping("/abc")//请求路径
    public class UserController{ 
        @Autowired//自动初始化对象
        UserService userService;
        @GetMapping("/getUser")//请求路径
        public String getUser(int id){ 
            System.out.print("id = "+id);
            return userService.Sel(id).toString();
        }
    }

1.  浏览器显示查询结果  
    输入网址：http://localhost:8888/abc/getUser?id=1  
    显示结果：![在这里插入图片描述][20191101145129732.png]

[GitHub]: https://github.com/yangshuaionline/YsService
[20191101145146949.png]: https://img-blog.csdnimg.cn/20191101145146949.png
[20191101145129732.png]: https://img-blog.csdnimg.cn/20191101145129732.png