REST：@autowired aircraftService上的java.lang.NullPointerExceptionException

我目前正在嘗試在java（球衣）中使用MongoDB創建一個restful webservice。REST：@autowired aircraftService上的java.lang.NullPointerExceptionException

我試圖返回當前在mongodb數據庫集合中的所有條目。

在運行Tomcat服務器即時得到以下錯誤：

Sep 30, 2014 1:02:21 PM com.sun.jersey.spi.container.ContainerResponse mapMappableContainerException 
SEVERE: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container 
java.lang.NullPointerException 
    at rest.Resource.AircraftResource.findAllAircraft(AircraftResource.java:46) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) 
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185) 
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) 
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302) 
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409) 
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:540) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:715) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) 
    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.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:534) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1081) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658) 
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Unknown Source) 

Sep 30, 2014 1:02:21 PM org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/projectPiranha] threw exception 
java.lang.NullPointerException 
    at rest.Resource.AircraftResource.findAllAircraft(AircraftResource.java:46) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    at java.lang.reflect.Method.invoke(Unknown Source) 
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) 
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185) 
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) 
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302) 
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409) 
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:540) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:715) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) 
    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.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:534) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1081) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658) 
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Unknown Source)

這是我的資源類

@Component 
    @Path("aircraft/") 
    @ManagedBean 
    public class AircraftResource implements IAircraftResource { 

     static final Logger logger = LoggerFactory.getLogger(AircraftResource.class); 
     @Autowired 
     private IAircraftService aircraftService; 

     @Context 
      private UriInfo uriInfo; 

     @Override 
     @GET 
     @Produces({MediaType.APPLICATION_JSON}) 
     public List<Aircraft> findAllAircraft() 
     { 
     List<Aircraft> results = aircraftService.findAllAircraft(); 
     return results; 
     }

aircraftService爲空。但是，這是我的服務類，它實現IAircraftService接口：

@Service 
@Scope("singleton") 
public class AircraftService implements IAircraftService { 

    static final Logger logger = LoggerFactory.getLogger(AircraftService.class); 

    @Autowired private IAircraftRepository aircraftRepository; 

    @Override 
    public List<Aircraft> findAllAircraft() 
    { 
     List<Aircraft> results = aircraftRepository.findAllAircraft(); 

     logger.info("Amount of Air-vehicles: {}", results.size()); 
     logger.info("Results: {}", results); 

     return results; 
    }

我的applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xmlns:context="http://www.springframework.org/schema/context" 
     xsi:schemaLocation="http://www.springframework.org/schema/beans 
     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
     http://www.springframework.org/schema/context 
     http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 

    <context:annotation-config/> 

    <context:component-scan base-package="rest"> 
    <context:exclude-filter type="annotation" expression="org.springframework.context.annotation.Configuration"/> 
    </context:component-scan> 

    <bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate"> 
    <constructor-arg name="mongo" ref="mongo"/> 
    <constructor-arg name="databaseName" value="iffdb"/> 
    </bean> 

    <bean id="mongo" class="org.springframework.data.mongodb.core.MongoFactoryBean"> 
    <property name="host" value="localhost"/> 
    </bean> 

    <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/> 

</beans>

請幫我！

來源

2014-10-01 AKndrp

哪一行是'AircraftResource.java：46' – Jaiwo99 2014-10-01 07:46:01

感謝評論46行：列表結果= aircraftService.findAllAircraft（）; – AKndrp 2014-10-01 07:50:47

令我困惑的是爲什麼之前沒有任何錯誤說「不能自動裝載...」似乎註釋被忽略 – 2014-10-01 08:16:58

它：

List<Aircraft> results = aircraftService.findAllAircraft();

aircraftService尚未設定，所以其空。調用它的方法將返回一個nullpointerexception。

來源

2014-10-01 07:57:03

如何設置它？我已經通過以下方式對其進行了定義： @Autowired private IAircraftService aircraftService; – AKndrp 2014-10-01 08:05:56

嘗試在AircraftResource中添加aircraftService字段的access-er（getter/setter）。

希望這有助於propably這一行的，因爲

來源

2014-10-01 07:22:59 hamitana

REST：@autowired aircraftService上的java.lang.NullPointerExceptionException

回答

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