微信公众号：一个优秀的废人如有问题或建议，请后台留言，我会尽力解决你的问题。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 2.1.3IDEAJDK 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>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile> <overwrite>true</overwrite> <verbose>true</verbose> </configuration> </plugin> </plugins> </build>代码解释很详细了，但这里提一嘴，mybatis generator 插件用于自动生成代码，pagehelper 插件用于物理分页。项目配置server: port: 8080spring: datasource: name: test url: jdbc:mysql://127.0.0.1:3306/test username: root password: 123456 #druid相关配置 type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.jdbc.Driver filters: stat maxActive: 20 initialSize: 1 maxWait: 60000 minIdle: 1 timeBetweenEvictionRunsMillis: 60000 minEvictableIdleTimeMillis: 300000 validationQuery: select ‘x’ testWhileIdle: true testOnBorrow: false testOnReturn: false poolPreparedStatements: true maxOpenPreparedStatements: 20## 该配置节点为独立的节点，有很多同学容易将这个配置放在spring的节点下，导致配置无法被识别mybatis: mapper-locations: classpath:mapping/*.xml #注意：一定要对应mapper映射xml文件的所在路径 type-aliases-package: com.nasus.mybatisxml.model # 注意：对应实体类的路径#pagehelper分页插件pagehelper: helperDialect: mysql reasonable: true supportMethodsArguments: true params: count=countSqlmybatis generator 配置文件这里要注意，配置 pom.xml 中 generator 插件所对应的配置文件时，在 Pom.xml 加入这一句，说明 generator 插件所对应的配置文件所对应的配置文件路径。这里已经在 Pom 中配置了，请见上面的 Pom 配置。${basedir}/src/main/resources/generator/generatorConfig.xmlgeneratorConfig.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.javapackage 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.javapackage com.nasus.mybatisxml.mapper;import com.nasus.mybatisxml.model.Student;import java.util.List;import org.apache.ibatis.annotations.Mapper;@Mapperpublic 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@Servicepublic 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…帮忙点个 star 可好？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
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