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详解mybatis-plus配置找不到Mapper接口路径的坑

时间：2020-10-19来源：www.pcxitongcheng.com作者：电脑系统城

mybatis-plus今天遇到一个问题，就是mybatis 没有读取到mapper.xml 文件。

特此记录一下，问题如下：

at com.baomidou.mybatisplus.core.override.MybatisMapperMethod$SqlCommand.<init>(MybatisMapperMethod.java:242)
at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.<init>(MybatisMapperMethod.java:54)
at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.lambda$cachedMapperMethod$0(MybatisMapperProxy.java:65)
at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.cachedMapperMethod(MybatisMapperProxy.java:65)
at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:60)
at com.sun.proxy.$Proxy72.findUserByName(Unknown Source)
at com.husy.service.impl.SystemUserServiceImpl.findUserByName(SystemUserServiceImpl.java:23)org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.husy.mapper.SystemUserMapper.findUserByName

错误代码如下：

mapper.xml 目录

在这里插入图片描述

代码如下：

单元测试

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5 @Test
public void findUser(){
SystemUser systemUser= systemUserService.findUserByName("admin");
System.out.println(systemUser.toString());
}

mybatis-puls 配置

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13 @EnableTransactionManagement
@Configuration
@MapperScan("com.husy.mapper")
public class MybatisConfig {

/**
* mybatis-plus 分页插件
*/
@Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}
}

service实现

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10 @Service
public class SystemUserServiceImpl implements SystemUserService {
@Autowired
private SystemUserMapper userMapper;

@Override
public SystemUser findUserByName(String name) {
return userMapper.findUserByName(name);
}
}

mapper 接口

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4 @Component
public interface SystemUserMapper {
SystemUser findUserByName(@Param("userAccount") String name);
}

mapper.xml

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19 <?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.husy.mapper.SystemUserMapper">
<resultMap id="systemUserMap" type="com.husy.domain.SystemUser" >
<id column="user_id" property="userId" />
<result column="user_account" property="userAccount" />
<result column="user_password" property="userPassword" />
<result column="user_phone" property="userPhone" />
</resultMap>
<select id="findUserByName" resultMap="systemUserMap">
SELECT
user_id,
user_account,
user_password,
user_phone
FROM t_system_user
where user_account = #{userAccount}
</select>
</mapper>

通过上面的代码可以看出。mapper接口中的方法和映射文件中的方法名称是一样的。不存在名称错误导致的情况，返回值，参数类型等你都正确。如果找不到方法，那一定是映射文件配置问题，只有没有读取到，才会出现找不到的情况。
我的配置如下：

问题出错的关键位置

我这里引用的是 mybatis-plus-boot-starte 依赖

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5 <dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.1.0</version>
</dependency>

mapper.xml 的文件引用路径配置如下：

1	`mybatis.mapper-locations=classpath:mapper/*.xml`

这就导致，mybatis 读取不到 mapper映射文件。

经过查阅：

如果引用mybatis-plus-boot-starter 依赖，需要配置 mybatis-plus.mapper-locations
如果引用mybatis-plus 依赖，需要配置 mybatis.mapper-locations

如下：

引用 mybatis-plus 包

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5 <dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>3.1.0</version>
</dependency>

1	`mybatis.mapper-locations=classpath:mapper/*.xml`

引用 mybatis-plus-boot-starter 包

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5 <dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.1.0</version>
</dependency>

1	`mybatis-plus.mapper-locations=classpath:mapper/*.xml`

只要选用其中一种方式，就没有问题了。

今天看到评论区有小伙伴说没有作用，这里给了一份Demo ，有问题的小伙伴可以比对一下。

POM

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60 <?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>2.2.2.RELEASE</version>
<relativePath/> 
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>

<properties>
<java.version>1.8</java.version>
</properties>

<dependencies>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.1</version>
</dependency>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.3.0</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>

<?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>2.2.2.RELEASE</version>
    <relativePath/> 
  </parent>
  <groupId>com.example</groupId>
  <artifactId>demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>demo</name>
  <description>Demo project for Spring Boot</description>

<dependencies>
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>2.1.1</version>
    </dependency>

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus-boot-starter</artifactId>
      <version>3.3.0</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
      <exclusions>
        <exclusion>
          <groupId>org.junit.vintage</groupId>
          <artifactId>junit-vintage-engine</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
  </dependencies>

<build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

</project>

application.properties

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7 # DataSource Config
spring.datasource.url=jdbc:mysql://localhost:3306/db_husy?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT%2B8&zeroDateTimeBehavior=CONVERT_TO_NULL
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

mybatis-plus.mapper-locations=classpath:/mapper/*.xml

MybatisConfig

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10 @EnableTransactionManagement
@Configuration
@MapperScan("com.example.demo.mapper")
public class MybatisConfig {
/**mybatis-plus 分页插件*/
@Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}
}

其他文件基本没变化。附上目录

在这里插入图片描述

单元测试

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11 @SpringBootTest
class DemoApplicationTests {
@Autowired
SystemUserService systemUserService;
@Test
public void findUser(){
SystemUser systemUser= systemUserService.findUserByName("admin");
System.out.println(systemUser.toString());
}

}