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.ymlspring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/t_blog?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai username: root password: 123456mybatis: type-aliases-package: com.mybatislearn.mockingjay.entity mapper-locations: classpath:mapper/*.xmlserver: port: 8080UserMapper.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.javapackage 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：serviceUserService.javapackage com.mybatislearn.mockingjay.service;import com.mybatislearn.mockingjay.entity.User;public interface UserService { User queryUserByname(String name);}UserServiceImpl.javapackage 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;@Servicepublic class UserServiceImpl implements UserService{ @Autowired private UserMapper userMapper; @Override public User queryUserByname(String name) { User user = userMapper.loadUserByUsername(name); return user; }}Controllerpackage 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;@RestControllerpublic class UserController { @Autowired private 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.javapackage com.mybatislearn.mockingjay.entity;import lombok.Data;import lombok.ToString;import java.time.LocalDateTime;@Data@ToStringpublic 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2.5.3springboot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 statementorg.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.mybatislearn.mockingjay.mapper.UserMapper.loadUserByUsername at 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.entitymapper-locations: classpath:mapper/*.xml2、配置Mapper.xml的时候，注意<mapper>标签下的namespace是否正确<mapper namespace="com.mybatislearn.mockingjay.mapper.UserMapper">注意<resultMap>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);}
