Spring+mybaits配置遇到的问题

2021年，八月，在学习springboot+mybatis的时候遇到了一些问题：

1、spring启动错误

刚开始，在配置springboot＋mybaits的时候，根据网络上的博客，配置application.yml，配置UserMapper等文件

application.yml

spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/t_blog?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghaiusername: rootpassword: 123456
mybatis:type-aliases-package: com.mybatislearn.mockingjay.entitymapper-locations: classpath:mapper/*.xml
server:port: 8080

UserMapper.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.mybatislearn.mockingjay.mapper.UserMapper"><resultMap id="UserMap" type="com.mybatislearn.mockingjay.entity.User" ><id column="id" property="id" /><result column="avatar" property="avatar" /><result column="createTime" property="createTime" /><result column="email" property="email"  /><result column="nickname" property="nickname"  /><result column="password" property="password"  /><result column="type" property="type"  /><result column="updateTime" property="updateTime"  /><result column="username" property="username"  /></resultMap><!--  根据用户名查询用户--><select id="loadUserByUsername" resultMap="UserMap">select * from t_user where username=#{username}</select>
</mapper>

配置一个mapper接口

UserMapper.java

package com.mybatislearn.mockingjay.mapper;
import com.mybatislearn.mockingjay.entity.User;public interface UserMapper {User loadUserByUsername(String username);}

同时项目内也是MVC结构的：

service

UserService.java

package com.mybatislearn.mockingjay.service;
import com.mybatislearn.mockingjay.entity.User;public interface UserService {User queryUserByname(String name);
}

UserServiceImpl.java

package com.mybatislearn.mockingjay.service;import com.mybatislearn.mockingjay.entity.User;
import com.mybatislearn.mockingjay.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class UserServiceImpl implements  UserService{@Autowiredprivate UserMapper userMapper;@Overridepublic User queryUserByname(String name) {User user = userMapper.loadUserByUsername(name);return user;}
}

Controller

package com.mybatislearn.mockingjay.controller;import com.mybatislearn.mockingjay.entity.User;
import com.mybatislearn.mockingjay.mapper.UserMapper;
import com.mybatislearn.mockingjay.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class UserController {@Autowiredprivate UserService userService;@GetMapping("/getuser")public User GetUser(String name) {System.out.println(name);User user = userService.queryUserByname(name);return user;}
}

最后是一个User实体

User.java

package com.mybatislearn.mockingjay.entity;
import lombok.Data;
import lombok.ToString;
import java.time.LocalDateTime;@Data
@ToString
public class User {private Long id;private String avatar;private LocalDateTime createTime;private String email;private String nickname;private String password;private Integer type;private LocalDateTime updateTime;private String username;}

最后是pom文件，这里只取maven依赖

<dependencies><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>1.3.2</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>5.3.8</version></dependency>
</dependencies>

在配置完成后出现了springboot启动失败的问题：

打印的日志

APPLICATION FAILED TO STARTDescription:An attempt was made to call a method that does not exist. The attempt was made from the following location:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.createHandlerMethod(AbstractHandlerMethodMapping.java:341)The following method did not exist:'void org.springframework.web.method.HandlerMethod.<init>(java.lang.String, org.springframework.beans.factory.BeanFactory, org.springframework.context.MessageSource, java.lang.reflect.Method)'The method's class, org.springframework.web.method.HandlerMethod, is available from the following locations:```
jar:file:/C:/Users/xzh11/.m2/repository/org/springframework/spring-web/5.3.8/spring-web-5.3.8.jar!/org/springframework/web/method/HandlerMethod.class
```The class hierarchy was loaded from the following locations:```
org.springframework.web.method.HandlerMethod: file:/C:/Users/xzh11/.m2/repository/org/springframework/spring-web/5.3.8/spring-web-5.3.8.jar
```Action:Correct the classpath of your application so that it contains a single, compatible version of org.springframework.web.method.HandlerMethodProcess finished with exit code 0

在查阅资料后，我觉得是我使用的spring版本的问题，项目内我使用的是2.5.4snapshot

<version>2.5.4-SNAPSHOT</version>

进入官网后，看到springboot最新的稳定版本为2.5.3

springboot官网

替换springboot版本为2.5.3

<version>2.5.3</version>

成功启动springboot！

2、mybais报错 Invalid bound statement

在启动springboot后，对Controller进行测试，结果出现mybatis报错Invalid bound statement

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.mybatislearn.mockingjay.mapper.UserMapper.loadUserByUsernameat org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:235) ~[mybatis-3.5.6.jar:3.5.6]at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:53) ~[mybatis-3.5.6.jar:3.5.6]at org.apache.ibatis.binding.MapperProxy.lambda$cachedInvoker$0(MapperProxy.java:115) ~[mybatis-3.5.6.jar:3.5.6]at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708) ~[na:na]at org.apache.ibatis.binding.MapperProxy.cachedInvoker(MapperProxy.java:102) ~[mybatis-3.5.6.jar:3.5.6]at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:85) ~[mybatis-3.5.6.jar:3.5.6]at com.sun.proxy.$Proxy57.loadUserByUsername(Unknown Source) ~[na:na]at com.mybatislearn.mockingjay.service.UserServiceImpl.queryUserByname(UserServiceImpl.java:15) ~[classes/:na]at com.mybatislearn.mockingjay.controller.UserController.GetUser(UserController.java:21) ~[classes/:na]......

在折腾了一上午之后，发现还是配置的错误：

在UserMapper文件中的namespace没有写对！！！！！

<?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.mybatislearn.mockingjay.mapper.UserMapper"><resultMap id="UserMap" type="com.mybatislearn.mockingjay.entity.User" ><id column="id" property="id" /><result column="avatar" property="avatar" /><result column="createTime" property="createTime" /><result column="email" property="email"  /><result column="nickname" property="nickname"  /><result column="password" property="password"  /><result column="type" property="type"  /><result column="updateTime" property="updateTime"  /><result column="username" property="username"  /></resultMap><!--  根据用户名查询用户--><select id="loadUserByUsername" resultMap="UserMap">select * from t_user where username=#{username}</select>
</mapper>

3、总结

这次的错误排查用了我将近一天的时间，对于新手来说，太折磨了

于是，写一个文档进行记录，防止下次再遇到同样的问题。

springboot启动失败的时候，若日志显示找不到什么文件，估计是配置的问题。

配置项目的时候最好再官网上查查稳定的版本。

在配置mybatis的时候，容易犯的错误：

1、要注意属性文件中，实体类地址和mapper地址是否正确

type-aliases-package: com.mybatislearn.mockingjay.entity
mapper-locations: classpath:mapper/*.xml

2、配置Mapper.xml的时候，注意标签下的namespace是否正确

<mapper namespace="com.mybatislearn.mockingjay.mapper.UserMapper">

注意标签中的 type地址是否正确

<resultMap id="UserMap" type="com.mybatislearn.mockingjay.entity.User" >

映射语句中的 id 是否正确对应映射接口的方法名

<select id="loadUserByUsername" resultMap="UserMap">select * from t_user where username=#{username}
</select>

package com.mybatislearn.mockingjay.mapper;
import com.mybatislearn.mockingjay.entity.User;public interface UserMapper {User loadUserByUsername(String username);}
``

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记一次Springboot+mybaits配置经历