SpringBoot+MyBatis搭建JavaWeb工程

冷不防 2022-05-20 08:16 176阅读 0赞

### 一、场景 ###

搭建Javaweb项目的框架有很多，但是例如SpringMVC搭建都比较繁琐(各种XML)，所以该篇博客笔者将记录SpringBoot+Mybatis的整合搭建Java web工程  
关于SpringBoot的优点以及介绍，该篇博客叙述的比较清楚  
[SpringBoot是什么?有什么优点？][SpringBoot]

--------------------

### 二、场景分析 ###

##### 1.开发环境 #####

*  JDK：1.9
 *  SpringBoot：2.0
 *  Mybatis：3.2.x
 *  MySQL：5.5
 *  操作系统：windows
 *  IDE：IntelliJ IDEA 2018.1.5 x64

##### 2.项目目录 #####

![这里写图片描述][70]

##### 3、数据表 #####

+-------+-------------+------+-----+---------+-------+
    | Field | Type        | Null | Key | Default | Extra |
    +-------+-------------+------+-----+---------+-------+
    | id    | int(11)     | NO   | PRI | NULL    |       |
    | name  | varchar(32) | YES  |     | NULL    |       |
    +-------+-------------+------+-----+---------+-------+

--------------------

### 三、实现方案 ###

##### 1、构建启动类(DemoApplication) #####

> 一般IDEA会自动生成，但是必须知道的是：启动类的位置及其重要，因为它的位置决定了它能否扫描到相应的controller、service等，启动类会扫描它所在的当前包及其子包

@SpringBootApplication
    public class DemoApplication {
        public static void main(String[] args) {
            SpringApplication.run(DemoApplication.class, args);
        }
    }

##### 2、pom.xml中添加相应的依赖 #####

*  web依赖
 *  mybatis依赖
 *  mysql依赖
    
        
        <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>1.3.2</version>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

##### 3、配置application #####

#路径
    server.servlet.context-path=/demo
    
    #数据库配置信息
    spring.datasource.driver-class-name =com.mysql.jdbc.Driver
    spring.datasource.url = jdbc:mysql://localhost/springbootdemo?useUnicode=true&characterEncoding=utf8
    spring.datasource.username =root
    spring.datasource.password =1111
    
    #mybatis配置信息
    mybatis.typeAliasesPackage=com.example.demo.domain.User
    mybatis.mapperLocations=classpath:/mappers/UserMapper.xml 
    
    #项目编码配置信息
    spring.freemarker.template-loader-path=classpath:/templates/
    spring.freemarker.cache=false
    spring.freemarker.charset=UTF-8
    spring.freemarker.check-template-location=true
    spring.freemarker.content-type=text/html
    spring.freemarker.expose-request-attributes=true
    spring.freemarker.expose-session-attributes=true
    spring.freemarker.request-context-attribute=request
    spring.freemarker.suffix=.demo

--------------------

##### 4、构建实体类User #####

public class User {
        private Integer id; //用户id
        private String name;//用户姓名
    
        //省略构造器
        //省略setter和getter
        //省略toString
    }

--------------------

##### 5、构建UserMapper(与UserMapper.xml进行映射，Mapper可以理解为dao层) #####

@Mapper
    public interface UserMapper {
        User GetUserMessage(Integer id);
    }

##### 6、构建UserMapper.xml(mapper的映射文件) #####

<?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">
    
        <sql id="id_name">
            id,name
        </sql>
        <select id="GetUserMessage" parameterType="int" resultType="com.example.demo.domain.User">
        select
            <include refid="id_name"></include>
        from user where id = #{id}
        </select>
    
    </mapper>

##### 7、构建service层的接口及其实现类(相关业务逻辑，这里是查询) #####

> IUserService

public interface IUserService {
       public User FindUser(Integer id);
    }

> UserServiceImpl

@ComponentScan({"com.example.demo.mapper"})
    @Service
    public class UserServiceImpl implements IUserService {
        //装配UserMapper这个Bean
        @Resource
        private UserMapper userMapper;
    
        @Override
        public User FindUser(Integer id) {
            return userMapper.GetUserMessage(id);
        }
    }

##### 8、构建UserController(请求处理控制器) #####

> 这里采用@RestController注解，直接返回JSON给页面

@RestController
    @ComponentScan({"com.example.demo.service"})
    @MapperScan({"com.example.demo.mapper"})
    public class UserController {
        @Resource
        private IUserService userService;
    
        @GetMapping("/finduser")
        public User findUser(@RequestParam(value = "id") Integer id){
            return userService.FindUser(id);
        }
    }

![这里写图片描述][70 1]

###### 注意点 ######

如果将控制器中的@RestController改成@Controller，页面将无法显示，并且页面显示错误信息，因为@Controller都知道在SpringMVC中返回的是视图(返回值为页面名称)，所以如果想返回JSON就得用@RestController

![这里写图片描述][70 2]

--------------------

ok，这样一个SpringBoot+Mybatis项目就搭建成功了

[工程下载][Link 1]

[SpringBoot]: https://www.cnblogs.com/antime/p/8118825.html
[70]: /images/20220520/7507fd555b14422a95b25bd34e42ad18.png
[70 1]: /images/20220520/8d6b9b9ca1074250bc5ef8884a130ba3.png
[70 2]: /images/20220520/5d647e28e83348c09e0417cc3bea32ab.png
[Link 1]: https://download.csdn.net/download/w_linux/10542807