0

在我当前的 spring 项目中，我有这个类，它应该为来自不同控制器的多个视图提供一些 modelAttributes：

@ControllerAdvice
public class Model {
  @Autowired
  private CategoriaService categoria;

  @Autowired
  private ProdutoService produto;

  @Autowired
  private UsuarioService usuario;

  @Autowired
  private CredencialService credencial;

  @ModelAttribute("categorias")
  public List<Categoria> categorias() {
    return categoria.select();
  }

  @ModelAttribute("produtos")
  public List<Produto> produtos() {
    return produto.select();
  }

  @ModelAttribute("usuario")
  public Usuario usuario() {
    return usuario.findBy("username", SecurityContextHolder.getContext().getAuthentication().getName());
  }

  @ModelAttribute("credenciais")
  public List<Credencial> credenciais() {
    return credencial.select();
  }
}

现在，我的视图分布在 2 个类中：

@Controller
public class Home {
...
}

/具有公共页面的视图，例如/signin和/signup。和：

public abstract class Controller<E> {
  private Class<E> clazz;

  @Autowired
  protected Service<E> serv;

  public Controller(Class<E> clazz) {
    this.clazz = clazz;
  }

  ...
}

一个通用类，它定义了对模型层类的操作的映射，例如插入、更新和删除。一些模型类用它们自己的映射扩展了这个类。

现在，当我尝试访问这些扩展方法（使用XMLHttpRequest）时，我收到了这个错误：

java.lang.NullPointerException: null
    at org.loja.Model.usuario(Model.java:43) ~[classes/:1.0-SNAPSHOT]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.method.annotation.ModelFactory.invokeModelAttributeMethods(ModelFactory.java:142) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.method.annotation.ModelFactory.initModel(ModelFactory.java:111) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:869) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[servlet-api.jar:na]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[servlet-api.jar:na]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:9.0.14]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-websocket.jar:9.0.14]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:384) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312) ~[catalina.jar:9.0.14]
    at org.springframework.boot.web.servlet.support.ErrorPageFilter.handleErrorStatus(ErrorPageFilter.java:164) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:132) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.web.servlet.support.ErrorPageFilter.access$000(ErrorPageFilter.java:66) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.web.servlet.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:105) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:123) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:9.0.14]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[catalina.jar:9.0.14]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[catalina.jar:9.0.14]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[catalina.jar:9.0.14]
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668) ~[catalina.jar:9.0.14]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[catalina.jar:9.0.14]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[catalina.jar:9.0.14]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) ~[tomcat-coyote.jar:9.0.14]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) ~[tomcat-coyote.jar:9.0.14]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) ~[tomcat-coyote.jar:9.0.14]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) ~[tomcat-coyote.jar:9.0.14]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-coyote.jar:9.0.14]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-util.jar:9.0.14]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

其中第 43 行对应于：

return usuario.findBy("username", SecurityContextHolder.getContext().getAuthentication().getName());

调用时导致此错误的方法之一是：

  @RequestMapping("download/{id}")
  @ResponseBody
  public byte[] download(@PathVariable("id") Integer id) throws IOException {
    return this.serv.download(id);
  }

任何人都知道如何解决这个问题？

4

1 回答 1

0

如果不存在身份验证，则 SecurityContext 为 getAuthentication() 返回 NULL。如果您合并公共和非公共页面的代码，请确保您的应用程序可以处理此问题。

返回： Authentication；如果没有可用的身份验证信息，则返回 null

请参阅：https ://docs.spring.io/spring-security/site/docs/4.2.11.BUILD-SNAPSHOT/apidocs/org/springframework/security/core/context/SecurityContext.html#getAuthentication--

于 2019-02-06T12:52:37.750 回答