springboot集成mybatis时提示有多个Mapper（dao）实例

[古甲哈醒]

我在使用springboot集成mybatis后，项目编译成功，但是在启动Application运行项目时，提示dao（mapper接口）有多个实例。
错误信息如下

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-05-22 10:51:45.858 ERROR 2076 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

file [E:\Workspaces\springboot-mybatis\target\classes\springboot\dao\CityDao.class] required a single bean, but 4 were found:
	- &cityDao: defined in file [E:\Workspaces\springboot-mybatis\target\classes\springboot\dao\CityDao.class]
	- systemEnvironment: a programmatically registered singleton	- contextParameters: a programmatically registered singleton	- contextAttributes: a programmatically registered singleton

Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

springboot\dao\CityDao.class，这个CityDao是我定义的一个Mapepr接口，它被service层引用。
其他配置和代码如下：
1、application.properties

## jdbc source
spring.datasource.url=jdbc:mysql://localhost:3306/springbootdb?useUnicode=true&characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

## Mybatis
mybatis.typeAliasesPackage=springboot.entity
mybatis.mapperLocations=classpath\:mapper/*.xml

2、CityDao.java

public interface CityDao {
	
	City get(int id);

}

3、cityMapper.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="springboot.dao.CityDao" >
	<resultMap type="springboot.entity.City" id="BaseResultMap">
		<id column="id" property="id" />
		<result column="province_id" property="provinceId" />
		<result column="city_name" property="cityName" jdbcType="VARCHAR"/>
		<result column="description" property="description" jdbcType="VARCHAR"/>
	</resultMap>
	
	<sql id="Base_Column_List" >
		id,province_id,city_name,description
	</sql>
	<select id="get" parameterType="java.lang.Integer" resultMap="BaseResultMap">
		select
		<include refid="Base_Column_List"/>
		from city
		where id = #{id}
	</select>
</mapper> 

4、CityServiceImpl.java

@Service
public class CityServiceImpl implements CityService{
	
	@Autowired
	private CityDao cityDao;
	
	public City get(String id){
		return cityDao.get(Integer.parseInt(id));
	}

}

5、App.java 负责启动springboot

package springboot;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
@MapperScan("springboot.dao")
public class App 
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

我检查了半天也没找出原因，请大神们指教，谢谢！

[北九道]

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed 感觉是bean的声明上有问题，对bean处理

[一剑侵心]

个人感觉应该是CityDao定义了多份的问题。

[sinat_21706277]

跟你遇到了一样的问题。。。

[owhen]

CityDao是不是要和mapper同名？ 这个问题这么久了，请教一下你

[Cathy313]

required a single bean, but 4 were found:CityDao需要单个bean但是发现了4个 建议：Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed 把其中一个bean标记成主键，更新**去接受多bean或者使用@Qualifier 去定义bean 你可以参考下http://blog.csdn.net/u014086917/article/details/77870779看看能不能解决

[herriman]

肯定出现了多个接口类型的实例，可以用LIST接收

[herriman]

MD，前面不小心用快捷键提交了。

肯定出现了多个接口类型的实例，可以用MAP接收找找原因
@Autowired
private Map<String,CityDao> CityDaoMap;
再打出来这个MAP的KEY，就知道是什么名字的对象了。

[你看咩啊]

返回的是集合，你用单个对象接收的，换成List<City>