Spring Data JPA存储库抛出空指针

时间：2016-05-25 17:21:54

标签： java spring hibernate spring-mvc spring-data-jpa

我一直在使用Spring Boot的Spring Data。使用JavaConfig文档，我已经设置了一个Spring JPA配置，但是当我在我的存储库中调用save方法时，会抛出一个空指针。

我的存储库：

import org.springframework.data.jpa.repository.JpaRepository;

public interface HouseRepository extends JpaRepository<House, Long> {
}

我的POJO：

AbstractHouse 

@MappedSuperclass
@Table(name="houses")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public abstract class AbstractHouse implements Serializable {

@NotEmpty
private String houseName;

@NotEmpty
private String houseNumber;

楼

@Entity
public class SmallHouse extends AbstractHouse {

@Id
@GeneratedValue
private Long id;

private Date created;

private Date updated;

然后我得到了一个服务对象，该服务对象采用Autowired存储库并尝试使用通过JPA获得的方法进行保存：

@Service
public class HouseService {

@Autowired
protected HouseRepository houseRepository;

public void save(House house) {
    houseRepository.save(house);
}

我的应用程序类包含：

@SpringBootApplication
@EnableScheduling
@EnableJpaRepositories
public class Application {

public static void main(String[] args) throws Exception {
    SpringApplication.run(Application.class, args);
}
}

我是Spring Data的新手，所以我确实认为它在配置中我缺少的东西，任何建议都将不胜感激！

- 更新 -

堆栈追踪：

java.lang.NullPointerException
    at com.jm.service.HouseService.save(HouseService.java:15)
    at com.jm.service.HouseClass.gatherHouses(HouseClass.java:43)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:775)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

我称之为方法：

public class HouseMain {

    @Autowired
    public HouseService houseService;

    public void gatherHouse() {
    houseService = new HouseService();
    House h = new House();
    h.setHouseName("House1");
    h.setHouseNumber("12");
    try {

        HouseService.save(vmComp);          
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}
}

然后在我的控制器中，我打电话给house.gatherHouse

2 个答案:

答案 0 :(得分：7)

您目前手动实例化HouseService，而不是通过Spring实例化。在您创建的houseService对象中，您有HouseRepository houseRepository字段null，因为您没有以任何方式初始化它。如果您使用Spring及其Autowired功能，那么您应该从Spring上下文中获取HouseService的实例。例如。你可以@Autowired进入你的控制器类。

答案 1 :(得分：2)

这是不正确的：

 houseService = new HouseService();

因为您正在使用Spring，所以应该允许Spring创建所有bean，这就是使用@Autowired的原因，在这种情况下，initialised没有执行，而且houseRepository是null为public class ConflictItem<T> where T : new() { public T CurrentItem { get; set; } public T RequestedUpdateItem { get; set; } } 。

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