Java Spring数据存储库-NullPointerException

我试图从cassandra键空间加载实体。我无法找出代码中的错误所在。我在DAO类中得到一个空指针异常

下面是我的代码：

卡桑德拉酒店

服装套装

梳妆台

包com.suo.dao

import java.util.List;

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

import com.suo.pojo.DressSetDO;
import com.suo.repo.DressSetRepository;

@Component
public class DressSetDAO {

    @Autowired
    private DressSetRepository dressRepo;

    public List<DressSetDO> search(String id) {
        List<DressSetDO> list = dressRepo.findById(id);

        System.out.println(">>> DressSet List: " + list);
        return list;
    }
}

DressSetRepository

包com.suo.repo

import java.io.Serializable;
import java.util.List;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.suo.pojo.DressSetDO;

@Repository
public interface DressSetRepository extends CrudRepository<DressSetDO, Serializable>{
    List<DressSetDO> findById(String id);
}

错误

---

假设您应该修改DressSetDO POJO中的代码

在DressSetDO中，id应更改为

Long

@PrimaryKey
private Long id;

---

假设您应该修改DressSetDO POJO中的代码

在DressSetDO中，id应更改为

Long

@PrimaryKey
private Long id;

---

您可以共享

DressSetRepository

类代码吗。添加DressSetRepository代码可能有帮助您不需要在Repository界面上使用

@Repository

，事实上，它可能会干扰其他组件。DressSetRepository似乎没有问题。DressSetRepository未在DressSetDAO类中自动连接。在调用dressRepo.findById（id）之前，请先对dressRepo进行null检查，并查看其是否为null。您是否可以共享

DressSetRepository

类代码。添加DressSetRepository代码可能有帮助您不需要在Repository界面上使用

@Repository

，事实上，它可能会干扰其他组件。DressSetRepository似乎没有问题。DressSetRepository未在DressSetDAO类中自动连接。在调用dressRepo.findById（id）之前，请先对dressRepo进行null检查，看看它是否为null。primaryKey是一个UUID，长度不长。所以我用它作为字符串，只是试着用Long。我认为支持Spring数据存储库需要很长时间，primaryKey是一个UUID，而不是很长。所以我用它作为字符串，只是试着用Long。我认为支持Spring数据存储库应该需要很长时间

import java.io.Serializable;
import java.util.List;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.suo.pojo.DressSetDO;

@Repository
public interface DressSetRepository extends CrudRepository<DressSetDO, Serializable>{
    List<DressSetDO> findById(String id);
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.suo.dao.DressSetDAO;

@SpringBootApplication
public class Application {

    @Autowired
    private static DressSetDAO dressDao;

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
        dressDao = new DressSetDAO();
        if(dressDao != null) {
            dressDao.search("1");
        } else {
            System.out.println("DressSetDAO bean is not autowired !");
        }
    }
}

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.2.RELEASE)

2017-04-04 16:29:03.129  INFO 17034 --- [           main] com.example.Application                  : Starting Application on Rams-MacBook-Pro.local with PID 17034 (/Users/Chandra/Documents/workspace-sts-3.8.3.RELEASE/suitup.online/target/classes started by Chandra in /Users/Chandra/Documents/workspace-sts-3.8.3.RELEASE/suitup.online)
2017-04-04 16:29:03.132  INFO 17034 --- [           main] com.example.Application                  : No active profile set, falling back to default profiles: default
2017-04-04 16:29:03.176  INFO 17034 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@1d7acb34: startup date [Tue Apr 04 16:29:03 PDT 2017]; root of context hierarchy
2017-04-04 16:29:03.546  WARN 17034 --- [           main] f.a.AutowiredAnnotationBeanPostProcessor : Autowired annotation is not supported on static fields: private static com.suo.dao.DressSetDAO com.example.Application.dressDao
2017-04-04 16:29:03.833  INFO 17034 --- [           main] com.datastax.driver.core.ClockFactory    : Using native clock to generate timestamps.
2017-04-04 16:29:03.978  INFO 17034 --- [           main] com.datastax.driver.core.NettyUtil       : Did not find Netty's native epoll transport in the classpath, defaulting to NIO.
2017-04-04 16:29:04.216  WARN 17034 --- [           main] com.datastax.driver.core.Cluster         : You listed localhost/0:0:0:0:0:0:0:1:9042 in your contact points, but it wasn't found in the control host's system.peers at startup
2017-04-04 16:29:04.305  INFO 17034 --- [           main] c.d.d.c.p.DCAwareRoundRobinPolicy        : Using data-center name 'datacenter1' for DCAwareRoundRobinPolicy (if this is incorrect, please provide the correct datacenter name with DCAwareRoundRobinPolicy constructor)
2017-04-04 16:29:04.306  INFO 17034 --- [           main] com.datastax.driver.core.Cluster         : New Cassandra host localhost/127.0.0.1:9042 added
2017-04-04 16:29:04.396  INFO 17034 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2017-04-04 16:29:04.407  INFO 17034 --- [           main] com.example.Application                  : Started Application in 11.497 seconds (JVM running for 11.768)
Exception in thread "main" java.lang.NullPointerException
    at com.suo.dao.DressSetDAO.search(DressSetDAO.java:18)
    at com.example.Application.main(Application.java:19)

@PrimaryKey
private Long id;