在REST调用中访问DAO TOMCAT

Question

我想在使用REST调用时通过我的dao访问数据。我的dao与webapp很好地协作。但是当我使用我创建的Web服务时，我有一个空指针异常。

这里是我的代码：

@Path("/hello") 

public class HelloWorldResource { 

@Inject 
private IAppDao appDao; 

@GET 
@Produces(MediaType.APPLICATION_XML) 
@Path("/{idApp}/{currentVersion}") 
public Object checkUpdate(@PathParam("idApp") String idApp, 
     @PathParam("currentVersion") String currentVersion) { 
    if(idApp == null || idApp.isEmpty() || currentVersion == null || currentVersion.isEmpty()) 
    { 
     ErrorResponse error = new ErrorResponse(); 
     error.setCode(400); 
     error.setMessage("bad_request_error"); 
     error.setReturnUrl(false); 
     return Response.status(400).entity(error).build(); 
    } 

    App app = appDao.findAppByName(idApp); 
    if(app != null) 
    { 
     AppResponse response = new AppResponse(); 
     response.setDataVersion(app.getDataVersion()); 
     response.setName(app.getName()); 
     response.setUpdatable(app.isUpdatable()); 
     response.setVersion(app.getVersion()); 
     return Response.status(200).entity(response).build(); 
    } 
    else 
    { 
     ErrorResponse error = new ErrorResponse(); 
     error.setCode(400); 
     error.setMessage("bad_app_name_error"); 
     error.setReturnUrl(false); 
     return Response.status(400).entity(error).build(); 
    } 
} 

和错误堆栈：

12 mars 2014 15:42:33 com.sun.jersey.spi.container.ContainerResponse mapMappableContainerException 
GRAVE: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container 
java.lang.NullPointerException 
    at com.mlwebanddev.website.front.jersey.HelloWorldResource.checkUpdate(HelloWorldResource.java:38) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
    at java.lang.reflect.Method.invoke(Method.java:597) 
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) 
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ObjectOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:258) 
    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.RightHandPathRule.accept(RightHandPathRule.java:147) 
    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:723) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:113) 
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:175) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at com.mlwebanddev.website.tools.Log4jFilter.doFilter(Log4jFilter.java:49) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) 
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861) 
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606) 
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) 
    at java.lang.Thread.run(Thread.java:695) 

空指针是在该行：

App app = appDao.findAppByName(idApp); 

任何想法来解决这个问题？

感谢

Answer 1

在我的applicationContext.xml的配置是：

<bean id="entityManagerFactory" 
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> 
<property name="dataSource" ref="dataSource" /> 
<property name="persistenceUnitName" value="resthub" /> 
<property name="persistenceUnitManager" ref="scanningPersistenceUnitManager" /> 
<property name="jpaDialect"> 
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" /> 
</property> 
<property name="jpaVendorAdapter"> 
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> 
<property name="showSql" value="false" /> 
</bean> 
</property> 
<property name="jpaProperties"> 
<map> 
<entry key="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" /> 
<!-- Utile juste pour créer les tables EN LOCAL, ne pas commiter décommenté --> 
<entry key="hibernate.hbm2ddl.auto" value="update" /> 
</map> 
</property> 
</bean> 

Answer 2

我买了我的@Stateless EJB同样的问题。

我解决了它，在公共类的声明之上添加了@Stateless。像这样：

@Path("/hello") 
@Stateless 
public class HelloWorldResource { 

@EJB 
private DaoHello daoHello; 


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