SpringBoot 实战 (十三) | 整合 MyBatis (XML 版)

╰半橙微兮° 2022-03-15 05:36 218阅读 0赞

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## 前言 ##

如题，今天介绍 SpringBoot 与 Mybatis 的整合以及 Mybatis 的使用，之前介绍过了 SpringBoot 整合MyBatis 注解版的使用，上一篇介绍过 MyBatis 的理论，今天这篇就不介绍 MyBatis 的理论了，有兴趣的跳转阅读：[SpringBoot 实战 (十三) | 整合 MyBatis (注解版)][SpringBoot _ _ _ _ MyBatis]

## 准备工作 ##

*  SpringBoot 2.1.3
 *  IDEA
 *  JDK 8

## 创建表 ##

CREATE TABLE `student`  (
      `id` int(32) NOT NULL AUTO_INCREMENT,
      `student_id` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '学号',
      `name` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '姓名',
      `age` int(11) NULL DEFAULT NULL COMMENT '年龄',
      `city` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '所在城市',
      `dormitory` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '宿舍',
      `major` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '专业',
      PRIMARY KEY (`id`) USING BTREE
    )ENGINE=INNODB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8;

## 引入依赖 ##

<dependencies>
            
            <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>2.0.0</version>
            </dependency>
            
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>1.1.14</version>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.47</version>
                <scope>runtime</scope>
            </dependency>
            
            <dependency>
                <groupId>com.github.pagehelper</groupId>
                <artifactId>pagehelper-spring-boot-starter</artifactId>
                <version>1.2.5</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
                
                <plugin>
                    <groupId>org.mybatis.generator</groupId>
                    <artifactId>mybatis-generator-maven-plugin</artifactId>
                    <version>1.3.2</version>
                    <configuration>
                        <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                        <overwrite>true</overwrite>
                        <verbose>true</verbose>
                    </configuration>
                </plugin>
            </plugins>
        </build>

代码解释很详细了，但这里提一嘴，mybatis generator 插件用于自动生成代码，pagehelper 插件用于物理分页。

## 项目配置 ##

server:
      port: 8080
    
    spring:
        datasource:
            name: test
            url: jdbc:mysql://127.0.0.1:3306/test
            username: root
            password: 123456
            #druid相关配置
            type: com.alibaba.druid.pool.DruidDataSource
            driver-class-name: com.mysql.jdbc.Driver
            filters: stat
            maxActive: 20
            initialSize: 1
            maxWait: 60000
            minIdle: 1
            timeBetweenEvictionRunsMillis: 60000
            minEvictableIdleTimeMillis: 300000
            validationQuery: select 'x'
            testWhileIdle: true
            testOnBorrow: false
            testOnReturn: false
            poolPreparedStatements: true
            maxOpenPreparedStatements: 20
    
    ## 该配置节点为独立的节点，有很多同学容易将这个配置放在spring的节点下，导致配置无法被识别
    mybatis:
      mapper-locations: classpath:mapping/*.xml  #注意：一定要对应mapper映射xml文件的所在路径
      type-aliases-package: com.nasus.mybatisxml.model  # 注意：对应实体类的路径
    
    #pagehelper分页插件
    pagehelper:
        helperDialect: mysql
        reasonable: true
        supportMethodsArguments: true
        params: count=countSql

## mybatis generator 配置文件 ##

这里要注意，配置 pom.xml 中 generator 插件所对应的配置文件时，在 Pom.xml 加入这一句，说明 generator 插件所对应的配置文件所对应的配置文件路径。这里已经在 Pom 中配置了，请见上面的 Pom 配置。

${basedir}/src/main/resources/generator/generatorConfig.xml

generatorConfig.xml ：

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
    <generatorConfiguration>
        
        <classPathEntry location="D:\repository\mysql\mysql-connector-java\5.1.47\mysql-connector-java-5.1.47.jar"/>
        <context id="DB2Tables" targetRuntime="MyBatis3">
            <commentGenerator>
                <property name="suppressDate" value="true"/>
                
                <property name="suppressAllComments" value="true"/>
            </commentGenerator>
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://127.0.0.1/test" userId="root" password="123456">
            </jdbcConnection>
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false"/>
            </javaTypeResolver>
            
            <javaModelGenerator targetPackage="com.nasus.mybatisxml.model" targetProject="src/main/java">
                <property name="enableSubPackages" value="true"/>
                <property name="trimStrings" value="true"/>
            </javaModelGenerator>
            
            <sqlMapGenerator targetPackage="mapping" targetProject="src/main/resources">
                <property name="enableSubPackages" value="true"/>
            </sqlMapGenerator>
            
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.nasus.mybatisxml.mapper" targetProject="src/main/java">
                <property name="enableSubPackages" value="true"/>
            </javaClientGenerator>
            
            <table tableName="student" domainObjectName="Student" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
        </context>
    </generatorConfiguration>

代码注释很详细，不多说。

## 生成代码过程 ##

第一步：选择编辑配置

![添加配置][1240]

第二步：选择添加 Maven 配置

![选择 Maven][Maven]

第三步：添加命令 mybatis-generator:generate -e 点击确定

![添加命令][1240 1]

第四步：运行该配置，生成代码

**特别注意！！！同一张表一定不要运行多次，因为 mapper 的映射文件中会生成多次的代码，导致报错，切记。如要运行多次，请把上次生成的 mapper 映射文件代码删除再运行。**

![运行该配置][1240 2]

第五步：检查生成结果

![生成的代码][1240 3]

## 遇到的问题 ##

请参照别人写好的遇到问题的解决方法，其中我就遇到**数据库时区不对**以及**只生成 Insert 方法**这两个问题。都是看以下这篇文章解决的：

[Mybatis Generator自动生成代码以及可能出现的问题][Mybatis Generator]

## 生成的代码 ##

1、实体类：Student.java

package com.nasus.mybatisxml.model;
    
    public class Student { 
    
        private Long id;
    
        private Integer age;
    
        private String city;
    
        private String dormitory;
    
        private String major;
    
        private String name;
    
        private Long studentId;
    
       // 省略 get 和 set 方法
    }

2、mapper 接口：StudentMapper.java

package com.nasus.mybatisxml.mapper;
    
    import com.nasus.mybatisxml.model.Student;
    import java.util.List;
    import org.apache.ibatis.annotations.Mapper;
    
    @Mapper
    public interface StudentMapper { 
        int deleteByPrimaryKey(Long id);
    
        int insert(Student record);
    
        int insertSelective(Student record);
    
        Student selectByPrimaryKey(Long id);
    
        // 我添加的方法，相应的要在映射文件中添加此方法
        List<Student> selectStudents();
    
        int updateByPrimaryKeySelective(Student record);
    
        int updateByPrimaryKey(Student record);
    }

3、映射文件：StudentMapper.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="com.nasus.mybatisxml.mapper.StudentMapper" >
      <resultMap id="BaseResultMap" type="com.nasus.mybatisxml.model.Student" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="age" property="age" jdbcType="INTEGER" />
        <result column="city" property="city" jdbcType="VARCHAR" />
        <result column="dormitory" property="dormitory" jdbcType="VARCHAR" />
        <result column="major" property="major" jdbcType="VARCHAR" />
        <result column="name" property="name" jdbcType="VARCHAR" />
        <result column="student_id" property="studentId" jdbcType="BIGINT" />
      </resultMap>
    
      <sql id="Base_Column_List" >
        id, age, city, dormitory, major, name, student_id
      </sql>
    
      <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long" >
        select 
        <include refid="Base_Column_List" />
        from student
        where id = #{id,jdbcType=BIGINT}
      </select>
    
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Long" >
        delete from student
        where id = #{id,jdbcType=BIGINT}
      </delete>
    
      <insert id="insert" parameterType="com.nasus.mybatisxml.model.Student" >
        insert into student (id, age, city, 
          dormitory, major, name, 
          student_id)
        values (#{id,jdbcType=BIGINT}, #{age,jdbcType=INTEGER}, #{city,jdbcType=VARCHAR}, 
          #{dormitory,jdbcType=VARCHAR}, #{major,jdbcType=VARCHAR}, #{name,jdbcType=VARCHAR}, 
          #{studentId,jdbcType=BIGINT})
      </insert>
    
      <insert id="insertSelective" parameterType="com.nasus.mybatisxml.model.Student" >
        insert into student
        <trim prefix="(" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            id,
          </if>
          <if test="age != null" >
            age,
          </if>
          <if test="city != null" >
            city,
          </if>
          <if test="dormitory != null" >
            dormitory,
          </if>
          <if test="major != null" >
            major,
          </if>
          <if test="name != null" >
            name,
          </if>
          <if test="studentId != null" >
            student_id,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides="," >
          <if test="id != null" >
            #{id,jdbcType=BIGINT},
          </if>
          <if test="age != null" >
            #{age,jdbcType=INTEGER},
          </if>
          <if test="city != null" >
            #{city,jdbcType=VARCHAR},
          </if>
          <if test="dormitory != null" >
            #{dormitory,jdbcType=VARCHAR},
          </if>
          <if test="major != null" >
            #{major,jdbcType=VARCHAR},
          </if>
          <if test="name != null" >
            #{name,jdbcType=VARCHAR},
          </if>
          <if test="studentId != null" >
            #{studentId,jdbcType=BIGINT},
          </if>
        </trim>
      </insert>
    
      <update id="updateByPrimaryKeySelective" parameterType="com.nasus.mybatisxml.model.Student" >
        update student
        <set >
          <if test="age != null" >
            age = #{age,jdbcType=INTEGER},
          </if>
          <if test="city != null" >
            city = #{city,jdbcType=VARCHAR},
          </if>
          <if test="dormitory != null" >
            dormitory = #{dormitory,jdbcType=VARCHAR},
          </if>
          <if test="major != null" >
            major = #{major,jdbcType=VARCHAR},
          </if>
          <if test="name != null" >
            name = #{name,jdbcType=VARCHAR},
          </if>
          <if test="studentId != null" >
            student_id = #{studentId,jdbcType=BIGINT},
          </if>
        </set>
        where id = #{id,jdbcType=BIGINT}
      </update>
    
      <update id="updateByPrimaryKey" parameterType="com.nasus.mybatisxml.model.Student" >
        update student
        set age = #{age,jdbcType=INTEGER},
          city = #{city,jdbcType=VARCHAR},
          dormitory = #{dormitory,jdbcType=VARCHAR},
          major = #{major,jdbcType=VARCHAR},
          name = #{name,jdbcType=VARCHAR},
          student_id = #{studentId,jdbcType=BIGINT}
        where id = #{id,jdbcType=BIGINT}
      </update>
    
      
      <select id="selectStudents" resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List" />
        from student
      </select>
    </mapper>

## serviec 层 ##

1、接口：

public interface StudentService { 
    
        int addStudent(Student student);
    
        Student findStudentById(Long id);
    
        PageInfo<Student> findAllStudent(int pageNum, int pageSize);
    
    }

2、实现类

@Service
    public class StudentServiceImpl implements StudentService{ 
    
        //会报错，不影响
        @Resource
        private StudentMapper studentMapper;
    
        /** * 添加学生信息 * @param student * @return */
        @Override
        public int addStudent(Student student) { 
            return studentMapper.insert(student);
        }
    
        /** * 根据 id 查询学生信息 * @param id * @return */
        @Override
        public Student findStudentById(Long id) { 
            return studentMapper.selectByPrimaryKey(id);
        }
    
        /** * 查询所有学生信息并分页 * @param pageNum * @param pageSize * @return */
        @Override
        public PageInfo<Student> findAllStudent(int pageNum, int pageSize) { 
            //将参数传给这个方法就可以实现物理分页了，非常简单。
            PageHelper.startPage(pageNum, pageSize);
            List<Student> studentList = studentMapper.selectStudents();
            PageInfo result = new PageInfo(studentList);
            return result;
        }
    }

## controller 层 ##

@RestController
    @RequestMapping("/student")
    public class StudentController { 
    
        @Autowired
        private StudentService studentService;
    
        @GetMapping("/{id}")
        public Student findStidentById(@PathVariable("id") Long id){ 
            return studentService.findStudentById(id);
        }
    
        @PostMapping("/add")
        public int insertStudent(@RequestBody Student student){ 
            return studentService.addStudent(student);
        }
    
        @GetMapping("/list")
        public PageInfo<Student> findStudentList(@RequestParam(name = "pageNum", required = false, defaultValue = "1") int pageNum,
                @RequestParam(name = "pageSize", required = false, defaultValue = "10") int pageSize){ 
            return studentService.findAllStudent(pageNum,pageSize);
        }
    }

## 启动类 ##

@SpringBootApplication
    @MapperScan("com.nasus.mybatisxml.mapper") // 扫描 mapper 接口，必须加上
    public class MybatisxmlApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(MybatisxmlApplication.class, args);
        }
    }

提一嘴，@MapperScan(“com.nasus.mybatisxml.mappe”) 这个注解非常的关键，这个对应了项目中 mapper(dao) 所对应的包路径，必须加上，否则会导致异常。

## Postman 测试 ##

1、插入方法：

![插入方法结果][1240 4]

2、根据 id 查询方法：

![根据 id 查询结果][id]

3、分页查询方法：

![分页查询结果][1240 5]

## 源码下载 ##

[https://github.com/turoDog/Demo/tree/master/springboot\_mybatisxml\_demo][https_github.com_turoDog_Demo_tree_master_springboot_mybatisxml_demo]

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## 后语 ##

如果本文对你哪怕有一丁点帮助，请帮忙点好看。你的好看是我坚持写作的动力。

另外，关注之后在发送 **1024** 可领取免费学习资料。资料内容详情请看这篇旧文：[Python、C++、Java、Linux、Go、前端、算法资料分享][Python_C_Java_Linux_Go]

![一个优秀的废人][1240 6]

[SpringBoot _ _ _ _ MyBatis]: https://www.jianshu.com/p/6050a6614af2
[1240]: /images/20220315/889c1640e58047adba76348475143e52.png
[Maven]: /images/20220315/fa4d833ce05c47c09f92322308ccb460.png
[1240 1]: /images/20220315/d41336b0c32340239687f97acf3a673a.png
[1240 2]: /images/20220315/9ac885309c0246f3be99f6ee8843f027.png
[1240 3]: /images/20220315/e6e94c02c8934e1b9a0df221b2642ae3.png
[Mybatis Generator]: https://blog.csdn.net/exalgentle/article/details/80844294
[1240 4]: /images/20220315/a190d9419b864ec4985de84fe5e9136f.png
[id]: /images/20220315/e1743380333a47c488169c77c7576aa6.png
[1240 5]: /images/20220315/9b88c3c3f67f41c7bfec8a3aa8f6fdaf.png
[https_github.com_turoDog_Demo_tree_master_springboot_mybatisxml_demo]: https://github.com/turoDog/Demo/tree/master/springboot_mybatisxml_demo
[Python_C_Java_Linux_Go]: https://www.jianshu.com/p/ed43dc8aa11e
[1240 6]: /images/20220315/bea0e894652e42649ed576b362d1924b.png