详解mybatis-plus的 mapper.xml 路径配置的坑

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：

org.apache.ibatis.binding.bindingexception: invalid bound statement (not found): com.husy.mapper.systemusermapper.finduserbyname

	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)

错误代码如下：

mapper.xml 目录

代码如下：

单元测试

@test
public void finduser(){
	systemuser systemuser= systemuserservice.finduserbyname("admin");
	system.out.println(systemuser.tostring());
}

mybatis-puls 配置

@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

@service
public class systemuserserviceimpl implements systemuserservice {
	@autowired
	private systemusermapper usermapper;

	@override
	public systemuser finduserbyname(string name) {
		return usermapper.finduserbyname(name);
	}
}

mapper 接口

@component
public interface systemusermapper {
	systemuser finduserbyname(@param("useraccount") string name);
}

mapper.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.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

<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：

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

<dependency>
  <groupid>com.baomidou</groupid>
  <artifactid>mybatis-plus</artifactid>
  <version>3.1.0</version>
</dependency>

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

引用 mybatis-plus-boot-starter 包

<dependency>
   <groupid>com.baomidou</groupid>
   <artifactid>mybatis-plus-boot-starter</artifactid>
   <version>3.1.0</version>
 </dependency>

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

<?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/> <!-- lookup parent from repository -->
  </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>

application.properties

# 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

@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

单元测试

@springboottest
class demoapplicationtests {
	@autowired
	systemuserservice systemuserservice;
	@test
	public void finduser(){
		systemuser systemuser= systemuserservice.finduserbyname("admin");
		system.out.println(systemuser.tostring());
	}

}

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