视频里面的代码不完整，搞了很久，导致查询结果是null，完整代码如下：

package com.imooc.demo.config.dao;

import org.mybatis.spring.SqlSessionFactoryBean;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.core.io.ClassPathResource;

import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;

import java.io.IOException;

@Configuration

public class SessionFactoryConfiguration {

    private static String mybatisConfigFile;

    @Value("${mybatis_config_file}")

    public void setMybatisConfigFile(String mybatisConfigFile) {

        SessionFactoryConfiguration.mybatisConfigFile = mybatisConfigFile;

    }

    private static String mapperPath;

    @Value("${mapper_path}")

    public void setMapperPath(String mapperPath) {

        SessionFactoryConfiguration.mapperPath = mapperPath;

    }

    @Value("${entity_package}")

    private String entityPackage;

    @Autowired

    @Qualifier("dataSource")

    private DataSource dataSource;

    @Bean(name = "sqlSessionFactory")

    public SqlSessionFactoryBean createSqlSessionFactoryBean() throws IOException {

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        sqlSessionFactoryBean.setConfigLocation(new ClassPathResource(mybatisConfigFile));

        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();

        String packageSearchPath = PathMatchingResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX + mapperPath;

        sqlSessionFactoryBean.setMapperLocations(resolver.getResources(packageSearchPath));

        sqlSessionFactoryBean.setDataSource(dataSource);

        sqlSessionFactoryBean.setTypeAliasesPackage(entityPackage);

        return sqlSessionFactoryBean;

    }

}