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准备工具:IDEA jdk1.8 Navicat for MySQL Postman
一、新建Project
选择依赖:mybatis Web Mysql JDBC
项目结构
pom依赖:
<?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 https://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>2.1.7.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.beilin</groupId> <artifactId>SpringBoot-Mybatis</artifactId> <version>0.0.1-SNAPSHOT</version> <name>SpringBoot-Mybatis</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <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> <!--导入mybatis依赖--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.0</version> </dependency> <!--导入mysql依赖--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.47</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> </plugins> </build> </project> pom.xml
二、创建user表
三、项目配置
1 .在com.beilin下创建controller包、mapper包,entity包;在resources文件夹下创建mapping文件夹(用来存放mapper映射的xml文件)
2.添加properties配置文件:application.properties
#配置mybatis #配置xml映射路径 mybatis.mapper-locations=classpath:mapping/*.xml #配置实体类别名 mybatis.type-aliases-package=com.beilin.entity #开启驼峰命名法 mybatis.configuration.map-underscore-to-camel-case=true #配置Mysql连接 spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC spring.datasource.username=root spring.datasource.password=123456 spring.datasource.driver-class-name=com.mysql.jdbc.Driver
3.在Springboot启动类添加@MapperScan注解
package com.beilin; import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @MapperScan(value = "com.beilin.mapper") @SpringBootApplication public class SpringbootApplication { public static void main(String[] args) { SpringApplication.run(SpringbootApplication.class, args); } } SpringbootApplication
四、代码实现
1.实体类User
package com.beilin.entity; public class User { /** * name:学生实体 */ //主键id private int id; //姓名 private String name; //年龄 private int age; // Get和 Set方法 public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } } User.java
2.数据操作层UserMapper
package com.beilin.mapper; import com.beilin.entity.User; import java.util.List; public interface UserMapper { //插入 public void insert(User user); //根据id删除 public void delete(Integer id); //根据user的id修改 public void update(User user); //根据id查询 public User getById(Integer id); //查询全部 public List<User> list(); } UserMapper.java
3.UserMapper映射文件
<?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.beilin.mapper.UserMapper"> <!-- 插入一个user --> <insert id="insert" parameterType="user"> insert into user(name,age) values(#{name},#{age}) </insert> <!-- 根据id删除学生 --> <delete id="delete" parameterType="int"> delete from user where id=#{id} </delete> <!-- 根据id修改学生信息 --> <update id="update" parameterType="user"> update user set name=#{name},age=#{age} where id=#{id} </update> <!-- 根据id查询 --> <select id="getById" parameterType="int" resultType="user"> select * from user where id=#{id} </select> <!-- 查询所有 --> <select id="list" parameterType="int" resultType="user"> select * from user </select> </mapper> UserMapper.xml
4.控制层UserController
package com.beilin.controller; import com.beilin.entity.User; import com.beilin.mapper.UserMapper; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; import java.util.List; @RestController public class UserController { @Autowired private UserMapper userMapper; //插入user @RequestMapping("/user") public void insert( User user) { userMapper.insert(user); } //根据id删除 @RequestMapping("/user1/{id}") public void delete(@PathVariable("id") Integer id) { userMapper.delete(id); } //修改 @RequestMapping("/user2/{id}") public void update(User user,@PathVariable("id") Integer id) { userMapper.update(user); } //根据id查询学生 @RequestMapping("/user3/{id}") public User getById(@PathVariable("id") Integer id) { User user = userMapper.getById(id); return user; } //查询全部 @RequestMapping("/users") public List<User> list(){ List<User> users = userMapper.list(); return users; } } UserController.java
测试使用PostMan或者直接在浏览器测试
过程中所遇到的问题:
报错:org.apache.ibatis.binding.BindingException: Invalid bound statement (not found)
解释:就是说,你的Mapper接口,被SpringBoot注入后,却无法正常的使用mapper.xml的sql;
首先检查下自己的代码是否错误,sql语句是否正确,在此基础上对照下面的解决方法。
这里的可能发生的情况有如下几种:
接口已经被扫描到,但是代理对象没有找到,即使尝试注入,也是注入一个错误的对象(可能就是null)接口已经被扫描到,代理对象找到了,也注入到接口上了,但是调用某个具体方法时,却无法使用(可能别的方法是正常的)
二者报错的结果是一样的,这里就提供几种排查方法:
1.mapper接口和mapper.xml是否在同一个包(package)下?名字是否一样(仅后缀不同)?
比如,接口名是UserMapper.java;对应的xml就应该是UserMapper.xml
2.mapper.xml的命名空间(namespace)是否跟mapper接口的包名一致?
比如,你接口的包名是com.beilin.mapper
,接口名是UserMapper.java
,那么你的mapper.xml的namespace应该是com.beilin.mapper.UserMapper
3.接口的方法名,与xml中的一条sql标签的id一致
比如,接口的方法List<User> GetById();那么,对应的xml里面一定有一条是
<selectid="GetById"parameterType="int" resultType="user">****</select>
4.如果接口中的返回值List集合(不知道其他集合也是),那么xml里面的配置,尽量用resultMap(保证resultMap配置正确),不要用resultType
5.最后,在编译后,到接口所在目录看一看,很有可能是没有生产对应的xml文件,因为maven默认是不编译的,因此,你需要在你的pom.xml的<build></build
>里面,加这么一段:
<resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> resources
总结
以上所述是小编给大家介绍的SpringBoot整合Mybatis实现CRUD,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对亿速云网站的支持!
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