Servlet[Jersey REST service]java.lang.NullPointerException的Servlet.service（）

有人能帮我解决这个问题吗。这是我第一次创建restful api

web.xml

 <display-name>1FxAll</display-name>
<servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>
  org.glassfish.jersey.servlet.ServletContainer
</servlet-class>
    <init-param>
      <param-name>jersey.config.server.provider.packages</param-name>
      <param-value>com.sample.blitz</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/api/*</url-pattern>
  </servlet-mapping>

完全堆栈跟踪错误

SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/1FxAll] threw exception [java.lang.NullPointerException] with root cause
java.lang.NullPointerException
    at com.sample.blitz.UserController.test(UserController.java:28)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:151)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:171)
    at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:195)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:104)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:384)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:342)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:101)
    at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:271)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:297)
    at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:254)
    at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1030)
    at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:373)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:381)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:344)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:221)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

它一直说错误在UserController第28行，但当我检查没有第28行时

我正在使用Tomcat7.0。我也试着切换到glassfish，但我得到了同样的错误

谢谢..

从@Path/user中删除并将其设置为@Pathuser。Bcoz，您已经在中给出了类似/api/*的路径，我认为/

将UserController类更改为

package com.sample.blitz;

@Path("user")
public class UserController{
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String test(){
        return "user";
    }
}

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我会把我的答案贴在这里

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我不确定glassfish 4.0和4.1的相关内容，但在我将glassfish版本从4.0更改为4.1并从lib文件夹中删除jersey文件后，它似乎可以工作，但在tomcat中，我仍然得到NullPointerException。这只适用于glassfish 4.1。

您已经为RESTFull添加了以下依赖项

<dependency>
    <groupId>org.glassfish.jersey.ext</groupId>
    <artifactId>jersey-spring3</artifactId>
</dependency>

<dependency>
    <groupId>org.glassfish.jersey.ext</groupId>
    <artifactId>jersey-bean-validation</artifactId>
</dependency>

---

当您创建服务对象时，用新的关键字实例化它

Xservice x = new Xservice();

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我想有一个调用/1FxAll path not/user？你是如何调用UserController的测试的？这是我使用的url。是/1FxAll是应用程序的显示名称还是其他名称？是，它是显示名称。我编辑了我的问题。我添加了显示名称。好的，从@Path/user中删除/设置为@Pathuser&让我们试试。Bcoz，你已经在url模式中给出了类似于/api/*的路径，我认为有两次出现/。这听起来不太可能。说明：@Path值可能以“/”开头，也可能不以“/”开头，这没有区别。同样，默认情况下，@Path值可能以“/”结尾，也可能不以“/”结尾，这没有什么区别，因此，以“/”结尾或不以“/”结尾的请求URL都将被匹配。这是错误的，对用户或不使用/

Xservice x = new Xservice();