SpringBoot入门整合Mybatis

绝地灬酷狼 2022-03-20 12:09 285阅读 0赞

### 前言： ###

上一篇讲了[SpringBoot的基本搭建][SpringBoot]

今天来整合一下mybatis框架，依然是使用Eclipse和Maven

SpringBoot配置mybatis有两种方式，一种为注解方式，一种为传统的用xml文件来存sql语句，今天介绍的是第二种

在开始整合之前，可以参考之前写的一篇博客：[简单搭建Mybatis框架实例][Mybatis]

这篇博客没有使用Spring等其他框架，就是新建java application然后只搭建了mybatis

在不使用其他框架，单纯搭建mybatis框架时，项目结构是这样的：

![70][]

> 一个dao接口文件   UserDao.java  
> 一个pojo实体类      User.java  
> 一个映射配置文件  UserMapper.xml，专门配置sql语句的

PS：这三个文件是Mybatis的必备三要素，mybatis-Generator自动生成代码也是生成这三个文件，基本上是一张数据库表对应三个文件

还有两个文件：

> 一个全局配置文件SqlMapConfig.xml   
> 一个测试文件

测试文件是程序入口，任何整合了mybatis框架的程序都会有一个入口  
而SqlMapConfig.xml 则是配置数据源和映射配置文件 XXXMapper.xml文件的，在不同程序中可以有不同的配置方法

但是不管怎么样，我的粗浅理解是，只要是Mybatis框架，就基本上得有这五个文件，三要素+全局配置文件+程序入口

### 准备： ###

首先得准备好数据库和表：

数据库为firstdb，表名为Student\_t:

![20190213093858880.png][]

新增一条记录：

![20190213093932167.png][]

### 开始： ###

**1、创建SpringBoot项目，和上篇一样的步骤 **

不同的是在选择项目dependencies的页卡那里，除了勾选Web->Web之外

再勾选Sql->Mysql，和Sql->Mybatis, 因为使用的是mysql数据库

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70][]

先看下完成后的最终项目结构图：

![20190212205718229.png][]

pom.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.1.2.RELEASE</version>
    		<relativePath /> 
    	</parent>
    	<groupId>cn.kevin</groupId>
    	<artifactId>mybatisPro</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>demo</name>
    	<description>Demo project for Spring Boot01</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    	</properties>
    
    	<dependencies>
    		<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>2.0.0</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-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    		
    		<dependency>
    			<groupId>com.alibaba</groupId>
    			<artifactId>druid</artifactId>
    			<version>1.1.0</version>
    		</dependency>
    	</dependencies>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    </project>

druid连接池是需要手动加上的，其余的则是通过创建项目时添加的依赖项，springboot自动帮我们生成的，如mybatis这些依赖

接下来我们一步步构建

**2、 先创建三要素**

三要素我是通过mybatis-Generator自动生成的代码

如何使用Mybatis-Generator生成代码，参考[另一篇博文(点击跳转)][Link 1]，这里不再赘述

实体类：Student

package cn.kevin.entity;
    
    public class Student {
        private Integer id;
    
        private String StudentName;
    
        private String password;
    
        private Integer age;
    
        //geter  setter 省略....
    }

dao接口文件  StudentDao

package cn.kevin.Dao;
    
    import cn.kevin.entity.Student;
    
    public interface StudentDao {
        int deleteByPrimaryKey(Integer id);
    
        int insert(Student record);
    
        int insertSelective(Student record);
    
        Student selectByPrimaryKey(Integer id);
    
        int updateByPrimaryKeySelective(Student record);
    
        int updateByPrimaryKey(Student record);
    }

还有就是Sql配置文件 StudentMaaper.xml ，在src/main/resource目录下

<?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.kevin.Dao.StudentDao" >
        <resultMap id="BaseResultMap" type="cn.kevin.entity.Student" >
            <id column="id" property="id" jdbcType="INTEGER" />
            <result column="Student_name" property="StudentName" jdbcType="VARCHAR" />
            <result column="password" property="password" jdbcType="VARCHAR" />
            <result column="age" property="age" jdbcType="INTEGER" />
        </resultMap>
        <sql id="Base_Column_List" >
            id, Student_name, password, age
        </sql>
        <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
            select
            <include refid="Base_Column_List" />
            from Student_t
            where id = #{id,jdbcType=INTEGER}
        </select>
        <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
            delete from Student_t
            where id = #{id,jdbcType=INTEGER}
        </delete>
        <insert id="insert" parameterType="cn.kevin.entity.Student" >
            insert into Student_t (id, Student_name, password,
            age)
            values (#{id,jdbcType=INTEGER}, #{StudentName,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR},
            #{age,jdbcType=INTEGER})
        </insert>
        <insert id="insertSelective" parameterType="cn.kevin.entity.Student" >
            insert into Student_t
            <trim prefix="(" suffix=")" suffixOverrides="," >
                <if test="id != null" >
                    id,
                </if>
                <if test="StudentName != null" >
                    Student_name,
                </if>
                <if test="password != null" >
                    password,
                </if>
                <if test="age != null" >
                    age,
                </if>
            </trim>
            <trim prefix="values (" suffix=")" suffixOverrides="," >
                <if test="id != null" >
                    #{id,jdbcType=INTEGER},
                </if>
                <if test="StudentName != null" >
                    #{StudentName,jdbcType=VARCHAR},
                </if>
                <if test="password != null" >
                    #{password,jdbcType=VARCHAR},
                </if>
                <if test="age != null" >
                    #{age,jdbcType=INTEGER},
                </if>
            </trim>
        </insert>
        <update id="updateByPrimaryKeySelective" parameterType="cn.kevin.entity.Student" >
            update Student_t
            <set >
                <if test="StudentName != null" >
                    Student_name = #{StudentName,jdbcType=VARCHAR},
                </if>
                <if test="password != null" >
                    password = #{password,jdbcType=VARCHAR},
                </if>
                <if test="age != null" >
                    age = #{age,jdbcType=INTEGER},
                </if>
            </set>
            where id = #{id,jdbcType=INTEGER}
        </update>
        <update id="updateByPrimaryKey" parameterType="cn.kevin.entity.Student" >
            update Student_t
            set Student_name = #{StudentName,jdbcType=VARCHAR},
            password = #{password,jdbcType=VARCHAR},
            age = #{age,jdbcType=INTEGER}
            where id = #{id,jdbcType=INTEGER}
        </update>
    </mapper>

**三、创建Controller  -- StudentController.java**

package cn.kevin.controller;
    
    import javax.annotation.Resource;
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import cn.kevin.entity.Student;
    import cn.kevin.service.StudentService;
    
    @RestController
    @EnableAutoConfiguration
    public class StudentController {
    
    	@Resource
    	private StudentService studentService;
    	
    	@RequestMapping("/showStudent")
    	public Student showStudent(HttpServletRequest request, Model model) {
    		
    		int StudentId = Integer.parseInt(request.getParameter("id"));
    		Student student = this.studentService.getStudentById(StudentId);
    		return student;
    	}
    }

拦截/showStudent，并且读取参数id,  然后调用service层，根据id查询数据库

**四、创建Service层**

创建接口 StudentService.java

package cn.kevin.service;
    import cn.kevin.entity.Student;
    
    public interface StudentService {
    
        public Student getStudentById(int StudentId);
    
        boolean addStudent(Student record);
    }

创建service实现类----StudentServiceImpl

package cn.kevin.service;
    
    import org.springframework.stereotype.Service;
    import cn.kevin.Dao.StudentDao;
    import cn.kevin.entity.Student;
    import javax.annotation.Resource;
    
    @Service
    public class StudentServiceImpl implements  StudentService {
    
    	@Resource
    	private StudentDao studentDao;
    
    	public Student getStudentById(int StudentId) {
    		return studentDao.selectByPrimaryKey(StudentId);
    	}
    
    	public boolean addStudent(Student record) {
    		boolean result = false;
    		try {
    			studentDao.insertSelective(record);
    			result = true;
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		return result;
    	}
    }

**五.全局配置文件 application.yml**

OK，现在mybatis三要素，service层，controller层都有了，还差什么？

还差一个全局配置文件，一般是配置数据源和映射配置文件的，在大多数地方都默认叫SqlMapConfig.xml

但在SpringBoot中，在本文中，我们新建一个application.yml

#默认使用配置
    spring:
      profiles:
        active: dev
    
    #mapperLocations指的路径是src/main/resources
    mybatis:
      typeAliasesPackage: com.kevin.entity
      mapperLocations: classpath:*.xml
    
    
    ---
    
    #开发配置
    spring:
      profiles: dev
    
      datasource:
        url: jdbc:mysql://localhost:3306/firstdb?characterEncoding=utf-8&serverTimezone=UTC
        username: root
        password: 123456
        driver-class-name: com.mysql.cj.jdbc.Driver
        # 使用druid
        type: com.alibaba.druid.pool.DruidDataSource

application.yml主要配置了数据源dataSource,和数据库连接池Druid ,指定mybatis映射文件的地址(mybatisLocation),既XXXMapper.xml的路径，springboot会扫描改路径下的xml

**六、在程序入口加入mappersacn**

好了，程序入口就是cn.kevin.DemoApplication.java里面的main函数，这个文件是系统默认创建的，我们需要为其添加mappersacn，让其扫描Dao层接口

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

我们启动试一下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70 1][]

### 遇到的问题： ###

1.Loading class \`com.mysql.jdbc.Driver'. This is deprecated. The new driver class is \`com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

提示我们com.mysql.jdbc.Driver已经不使用了，要使用最新的com.mysql.cj.jdbc.Driver

所以修改yml文件: com.mysql.jdbc.Driver 改成  com.mysql.cj.jdbc.Driver 即可

2.java.sql.SQLException: The server time zone value '?D1ú±ê×?ê±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.  
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~\[mysql-connector-java-8.0.13.jar:8.0.13\]

所以修改yml文件:  url: jdbc:mysql://localhost:3306/firstdb  后面加上 ?characterEncoding=utf-8&serverTimezone=UTC

[SpringBoot]: https://blog.csdn.net/wcc27857285/article/details/86999702
[Mybatis]: https://blog.csdn.net/wcc27857285/article/details/82315638
[70]: /images/20220320/5d83fabd60784126899412a26d047115.png
[20190213093858880.png]: /images/20220320/8a59825d2c1f44a38400bac44e1628b3.png
[20190213093932167.png]: /images/20220320/8eb204ee5af246548d05e50956d5dc21.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70]: /images/20220320/490a4c97a97e4b40ad423a41adb34622.png
[20190212205718229.png]: /images/20220320/a7c76617bcff4b7a98d796ac61e6af43.png
[Link 1]: https://blog.csdn.net/wcc27857285/article/details/87259371
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYzI3ODU3Mjg1_size_16_color_FFFFFF_t_70 1]: /images/20220320/6c31680e8817416bbc8fc6fdf5766009.png