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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)
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>
<!– jdbc 连接驱动 –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!– web 启动类 –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!– mybatis 依赖 –>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
<!– druid 数据库连接池 –>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.14</version>
</dependency>
<!– Mysql 连接类 –>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
<scope>runtime</scope>
</dependency>
<!– 分页插件 –>
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.5</version>
</dependency>
<!– test 依赖 –>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!– springboot maven 插件 –>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<!– mybatis generator 自动生成代码插件 –>
<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>
<!– 数据库驱动: 选择你的本地硬盘上面的数据库驱动包 –>
<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”/>
<!– 是否去除自动生成的注释 true：是：false: 否 –>
<property name=”suppressAllComments” value=”true”/>
</commentGenerator>
<!– 数据库链接 URL，用户名、密码 –>
<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>
<!– 生成模型的包名和位置 –>
<javaModelGenerator targetPackage=”com.nasus.mybatisxml.model” targetProject=”src/main/java”>
<property name=”enableSubPackages” value=”true”/>
<property name=”trimStrings” value=”true”/>
</javaModelGenerator>
<!– 生成映射文件的包名和位置 –>
<sqlMapGenerator targetPackage=”mapping” targetProject=”src/main/resources”>
<property name=”enableSubPackages” value=”true”/>
</sqlMapGenerator>
<!– 生成 DAO 的包名和位置 –>
<javaClientGenerator type=”XMLMAPPER” targetPackage=”com.nasus.mybatisxml.mapper” targetProject=”src/main/java”>
<property name=”enableSubPackages” value=”true”/>
</javaClientGenerator>
<!– 要生成的表 tableName 是数据库中的表名或视图名 domainObjectName 是实体类名 –>
<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
第二步：选择添加 Maven 配置
第三步：添加命令 mybatis-generator:generate -e 点击确定
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。
第五步：检查生成结果
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
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>
<!– 我添加的方法 –>
<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：
2、根据 id 查询方法：
3、分页查询方法：
源码下载
https://github.com/turoDog/De…
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