问题描述

springmvc+mybatis整合

spring-servlet.xml

<beans:bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource">
       <beans:property name="driverClassName" value="org.postgresql.Driver"/>
       <beans:property name="url"
           value="jdbc:postgresql://192.168.20.61:5432/atomdb"/>
       <beans:property name="username" value="postgre"/>
       <beans:property name="password" value="postgre"/>
    </beans:bean>
    <beans:bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
       <beans:property name="dataSource" ref="myDataSource"/>
       <beans:property name="configLocation" value="/WEB-INF/db/SqlMapConfig.xml"/>
    </beans:bean>
    <beans:bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
       <beans:property name="basePackage" value="Mapper"/>
    </beans:bean>
    <beans:bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
       <beans:property name="dataSource" ref="myDataSource"/>
    </beans:bean>

SqlMapConfig.xml

 <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <mappers>
        <mapper resource="ApiServiceRepoMapper.xml" />
    </mappers>

</configuration>

ApiServiceRepoMapper.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.shangpin.EChars.repo.ComplexQueryRepo">

        <select id="count" resultType="Integer">
            SELECT "count"(*) FROM "public"."search_keyword_statistic_day"
        </select>
        </mapper>

Controller.java

 @Controller
@RequestMapping("/search")
public class Controller {

    @Autowired
    private SearchService searchService ;

    @RequestMapping("/get")
    public void ss(){

        System.out.println(searchService.count());
    }
}

SearchService.java

 @Service
public class SearchService {
    @Autowired
    ComplexQueryRepo complexQueryRepo;

    @Autowired
    public int count(){
        System.out.println("222");
        int a = complexQueryRepo.count();
        return a;
    }
}

ComplexQueryRepo.java

 public interface ComplexQueryRepo{
    public int count();
}

项目能启动，发送请求/search/get后会输出222然后

    int a = complexQueryRepo.count();

这一行报空指针

解决方案

先不问你注解扫描是否开启
其他的代码问题太多了，springmvc用的动态代理，所有你的service要个接口，然后实现接口，然后注入，dao也是同样的
@Autowired
public int count(){
System.out.println("222");
int a = complexQueryRepo.count();
return a;
}
还有这，@Autowired这个是自动注入，就是将容器里的bean注入，所有这行去了

解决方案二：

借口里的count()实现在哪里？不是class SearchService里那个count()~

解决方案三：

select语句 count怎么加引号