SpringBoot（五）：SpringBoot整合MyBatis

刺骨的言语ヽ痛彻心扉 2022-05-29 13:40 184阅读 0赞

> 怎么说了，写博客虽然是一件很费时间的事情，而且还是个菜鸟，但是如果写的东西能够帮助到别人，还是值得开心的。

回顾：

> 上篇写了JdbcTemplate，但是想到使用Mybatis，JPA的人估计不少，所以这篇写一下SpringBoot整合Mybatis，JPA的话以后有时间再弄，因为自己也没用过。

### 一、数据准备 ###

其实还是上篇的，以防有人是直接看这篇的，就还是贴出来吧。

CREATE TABLE `tb_user` ( `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID', `username` varchar(50) NOT NULL COMMENT '用户名', `age` int(11) NOT NULL COMMENT '年龄', `ctm` datetime NOT NULL COMMENT '创建时间', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

INSERT INTO `db_test`.`tb_user` (`username`, `age`, `ctm`) VALUES('张三', '18', NOW()) ;
    INSERT INTO `db_test`.`tb_user` (`username`, `age`, `ctm`) VALUES('李四', '20', NOW()) ;
    INSERT INTO `db_test`.`tb_user` (`username`, `age`, `ctm`) VALUES('王五', '19', NOW()) ;

### 二、引入依赖 ###

<dependency>
    			<groupId>org.mybatis.spring.boot</groupId>
    			<artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.0</version> 	        </dependency>
    
    		
    		<dependency>
    			<groupId>mysql</groupId>
    			<artifactId>mysql-connector-java</artifactId>
    		</dependency>

另外web依赖也需要，因为我们采用MVC模式。

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

### 三、数据库配置文件 ###

spring:
      datasource:
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://localhost:3306/db_user
        username: root
        password: root

### 四、代码 ###

最开始使用mybati比较麻烦，各种配置文件、实体类、dao层映射关联、还有一大推其它配置。当然mybatis也发现了这种弊端，初期开发了generator可以根据表结果自动生产实体类、配置文件和dao层代码，可以减轻一部分开发量；后期也进行了大量的优化可以使用注解了。

于是两种使用方式都介绍一下，一、无配置注解版 二、配置文件版

#### 1.无配置文件注解版 ####

加入配置文件

mybatis:
      type-aliases-package: cn.saytime.bean

![这里写图片描述][SouthEast]

实体类User.class

package cn.saytime.bean;
    
    import java.util.Date;
    
    /** * @ClassName cn.saytime.bean.User * @Description * @date 2017-07-04 22:47:28 */
    public class User {
    
    	private int id;
    	private String username;
    	private int age;
    	private Date ctm;
    
    	public User() {
    	}
    
    	public User(String username, int age) {
    		this.username = username;
    		this.age = age;
    		this.ctm = new Date();
    	}
    
    	// Getter、Setter
    }

UserMapper.class

package cn.saytime.mapper;
    
    import cn.saytime.bean.User;
    import org.apache.ibatis.annotations.Delete;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Param;
    import org.apache.ibatis.annotations.Select;
    import org.apache.ibatis.annotations.Update;
    
    import java.util.List;
    
    // @Mapper 这里可以使用@Mapper注解，但是每个mapper都加注解比较麻烦，所以统一配置@MapperScan在扫描路径在application类中
    public interface UserMapper {
    
    	@Select("SELECT * FROM tb_user WHERE id = #{id}")
    	User getUserById(Integer id);
    
    	@Select("SELECT * FROM tb_user")
    	public List<User> getUserList();
    
    	@Insert("insert into tb_user(username, age, ctm) values(#{username}, #{age}, now())")
    	public int add(User user);
    
    	@Update("UPDATE tb_user SET username = #{user.username} , age = #{user.age} WHERE id = #{id}")
    	public int update(@Param("id") Integer id, @Param("user") User user);
    
    	@Delete("DELETE from tb_user where id = #{id} ")
    	public int delete(Integer id);
    }

> Mybatis 注解使用 [http://www.mybatis.org/mybatis-3/zh/java-api.html][http_www.mybatis.org_mybatis-3_zh_java-api.html]

UserService.class

package cn.saytime.service;
    
    import cn.saytime.bean.User;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    /** * @ClassName cn.saytime.service.UserService * @Description */
    public interface UserService {
    
    	User getUserById(Integer id);
    
    	public List<User> getUserList();
    
    	public int add(User user);
    
    	public int update(Integer id, User user);
    
    	public int delete(Integer id);
    }

UserServiceimpl.class

package cn.saytime.service.impl;
    
    import cn.saytime.bean.User;
    import cn.saytime.mapper.UserMapper;
    import cn.saytime.service.UserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    /** * @ClassName cn.saytime.service.impl.UserServiceImpl * @Description */
    @Service public class UserServiceImpl implements UserService {
    
    	@Autowired private UserMapper userMapper;
    
    	@Override public User getUserById(Integer id) {
    		return userMapper.getUserById(id);
    	}
    
    	@Override public List<User> getUserList() {
    		return userMapper.getUserList();
    	}
    
    	@Override public int add(User user) {
    		return userMapper.add(user);
    	}
    
    	@Override public int update(Integer id, User user) {
    		return userMapper.update(id, user);
    	}
    
    	@Override public int delete(Integer id) {
    		return userMapper.delete(id);
    	}
    }

JsonResult.class 通用json返回类

package cn.saytime.bean;
    
    public class JsonResult {
    
    	private String status = null;
    
    	private Object result = null;
    
    	public JsonResult status(String status) {
    		this.status = status;
    		return this;
    	}
    
    	// Getter Setter
    }

UserController.class（Restful风格）

package cn.saytime.web;
    
    import cn.saytime.bean.JsonResult;
    import cn.saytime.bean.User;
    import cn.saytime.service.UserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.List;
    
    /** * @ClassName cn.saytime.web.UserController * @Description * @date 2017-07-04 22:46:14 */
    @RestController
    public class UserController {
    
    	@Autowired
    	private UserService userService;
    
    	/** * 根据ID查询用户 * @param id * @return */
    	@RequestMapping(value = "user/{id}", method = RequestMethod.GET)
    	public ResponseEntity<JsonResult> getUserById (@PathVariable(value = "id") Integer id){
    		JsonResult r = new JsonResult();
    		try {
    			User user = userService.getUserById(id);
    			r.setResult(user);
    			r.setStatus("ok");
    		} catch (Exception e) {
    			r.setResult(e.getClass().getName() + ":" + e.getMessage());
    			r.setStatus("error");
    			e.printStackTrace();
    		}
    		return ResponseEntity.ok(r);
    	}
    
    	/** * 查询用户列表 * @return */
    	@RequestMapping(value = "users", method = RequestMethod.GET)
    	public ResponseEntity<JsonResult> getUserList (){
    		JsonResult r = new JsonResult();
    		try {
    			List<User> users = userService.getUserList();
    			r.setResult(users);
    			r.setStatus("ok");
    		} catch (Exception e) {
    			r.setResult(e.getClass().getName() + ":" + e.getMessage());
    			r.setStatus("error");
    			e.printStackTrace();
    		}
    		return ResponseEntity.ok(r);
    	}
    
    	/** * 添加用户 * @param user * @return */
    	@RequestMapping(value = "user", method = RequestMethod.POST)
    	public ResponseEntity<JsonResult> add (@RequestBody User user){
    		JsonResult r = new JsonResult();
    		try {
    			int orderId = userService.add(user);
    			if (orderId < 0) {
    				r.setResult(orderId);
    				r.setStatus("fail");
    			} else {
    				r.setResult(orderId);
    				r.setStatus("ok");
    			}
    		} catch (Exception e) {
    			r.setResult(e.getClass().getName() + ":" + e.getMessage());
    			r.setStatus("error");
    
    			e.printStackTrace();
    		}
    		return ResponseEntity.ok(r);
    	}
    
    	/** * 根据id删除用户 * @param id * @return */
    	@RequestMapping(value = "user/{id}", method = RequestMethod.DELETE)
    	public ResponseEntity<JsonResult> delete (@PathVariable(value = "id") Integer id){
    		JsonResult r = new JsonResult();
    		try {
    			int ret = userService.delete(id);
    			if (ret < 0) {
    				r.setResult(ret);
    				r.setStatus("fail");
    			} else {
    				r.setResult(ret);
    				r.setStatus("ok");
    			}
    		} catch (Exception e) {
    			r.setResult(e.getClass().getName() + ":" + e.getMessage());
    			r.setStatus("error");
    
    			e.printStackTrace();
    		}
    		return ResponseEntity.ok(r);
    	}
    
    	/** * 根据id修改用户信息 * @param user * @return */
    	@RequestMapping(value = "user/{id}", method = RequestMethod.PUT)
    	public ResponseEntity<JsonResult> update (@PathVariable("id") Integer id, @RequestBody User user){
    		JsonResult r = new JsonResult();
    		try {
    			int ret = userService.update(id, user);
    			if (ret < 0) {
    				r.setResult(ret);
    				r.setStatus("fail");
    			} else {
    				r.setResult(ret);
    				r.setStatus("ok");
    			}
    		} catch (Exception e) {
    			r.setResult(e.getClass().getName() + ":" + e.getMessage());
    			r.setStatus("error");
    
    			e.printStackTrace();
    		}
    		return ResponseEntity.ok(r);
    	}
    
    }

Application.java

package cn.saytime;
    
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    @MapperScan("cn.saytime.mapper")
    public class SpringbootMybaitsApplication { 
    
    	public static void main(String[] args) {
    		SpringApplication.run(SpringbootMybaitsApplication.class, args);
    	}
    }

使用PostMan通过测试。

#### 2.配置文件版 ####

加入配置文件

mybatis:
      mapper-locations: classpath:mybatis/mapper/*.xml
      config-location: classpath:mybatis/mybatis-config.xml

项目目录结构：

![这里写图片描述][SouthEast 1]

> 代码部分，相比于上面那种方式，改变的只有配置文件以及下面几个部分。

UserMapper.class

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <typeAliases>
        </typeAliases>
    </configuration>

userMapper.xml

<?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="cn.saytime.mapper.UserMapper" >
        <resultMap id="BaseResultMap" type="cn.saytime.bean.User" >
            <id column="id" property="id" jdbcType="INTEGER" />
            <result column="username" property="username" jdbcType="VARCHAR" />
            <result column="age" property="age" jdbcType="INTEGER" />
            <result column="ctm" property="ctm" jdbcType="TIMESTAMP"/>
        </resultMap>
    
        <sql id="Base_Column_List" >
            id, username, age, ctm
        </sql>
    
        <select id="getUserList" resultMap="BaseResultMap" >
            SELECT
            <include refid="Base_Column_List" />
            FROM tb_user
        </select>
    
        <select id="getUserById" parameterType="java.lang.Integer" resultMap="BaseResultMap" >
            SELECT
            <include refid="Base_Column_List" />
            FROM tb_user
            WHERE id = #{id}
        </select>
    
        <insert id="add" parameterType="cn.saytime.bean.User" >
            INSERT INTO
            tb_user
            (username,age,ctm)
            VALUES
            (#{username}, #{age}, now())
        </insert>
    
        <update id="update" parameterType="java.util.Map" >
            UPDATE
            tb_user
            SET
            username = #{user.username},age = #{user.age}
            WHERE
            id = #{id}
        </update>
    
        <delete id="delete" parameterType="java.lang.Integer" >
            DELETE FROM
            tb_user
            WHERE
            id = #{id}
        </delete>
    </mapper>

上面这种方式也使用PostMan通过测试。

### 五、简要说明 ###

不知道大家有没有注意到一点，就是引入Springboot-mybatis依赖的时候，并不是spring官方的starter，往常的springboot集成的依赖，比如web，redis等，groupId以及artifactId的地址如下：

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

而这里是mybatis为spring提供的starter依赖，所以依赖地址是：

<dependency>
    			<groupId>org.mybatis.spring.boot</groupId>
    			<artifactId>mybatis-spring-boot-starter</artifactId>
    			<version>1.3.0</version>
    		</dependency>

> 而且值得注意的是，这里必须要指定版本号，往常我们使用springboot之所以不需要指定版本号，是因为我们引入的Maven Parent 中指定了SpringBoot的依赖，SpringBoot官方依赖Pom文件中已经指定了它自己集成的第三方依赖的版本号，对于Mybatis，Spring官方并没有提供自己的starter，所以必须跟正常的maven依赖一样，要加版本号。

SpringBoot自己集成的starter依赖，可以查看 [http://docs.spring.io/spring-boot/docs/1.5.4.RELEASE/reference/htmlsingle/\#using-boot-starter][http_docs.spring.io_spring-boot_docs_1.5.4.RELEASE_reference_htmlsingle_using-boot-starter]

[SouthEast]: /images/20220529/267827e384344e01a4cfe9e88aca277a.png
[http_www.mybatis.org_mybatis-3_zh_java-api.html]: http://www.mybatis.org/mybatis-3/zh/java-api.html
[SouthEast 1]: /images/20220529/b6e8b45557464d2f80ba07915d9e1591.png
[http_docs.spring.io_spring-boot_docs_1.5.4.RELEASE_reference_htmlsingle_using-boot-starter]: http://docs.spring.io/spring-boot/docs/1.5.4.RELEASE/reference/htmlsingle/#using-boot-starter