Question

尝试访问我的本地主机服务时出现以下异常。

2019-01-22 13:57:27 ERROR o.a.c.c.C.[.[.[.[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException: null
    at org.springframework.data.rest.webmvc.RepositoryRestHandlerMapping.exposeEffectiveLookupPathKey(RepositoryRestHandlerMapping.java:264) ~[spring-data-rest-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.data.rest.webmvc.RepositoryRestHandlerMapping.lookupHandlerMethod(RepositoryRestHandlerMapping.java:165) ~[spring-data-rest-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(AbstractHandlerMethodMapping.java:347) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(AbstractHandlerMethodMapping.java:62) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandler(AbstractHandlerMapping.java:401) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.data.rest.webmvc.support.DelegatingHandlerMapping$HandlerSelectionResult.from(DelegatingHandlerMapping.java:108) ~[spring-data-rest-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.data.rest.webmvc.support.DelegatingHandlerMapping.getHandler(DelegatingHandlerMapping.java:74) ~[spring-data-rest-webmvc-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1231) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1014) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:998) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doOptions(FrameworkServlet.java:937) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:669) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:875) ~[spring-webmvc-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:770) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_181]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_181]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.12.jar:9.0.12]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]

我的RestConfiguration类是：

@Configuration
@EnableWebMvc
public class RestConfiguration implements RepositoryRestConfigurer, WebMvcConfigurer {

    @Autowired
    private EntityManager entityManager;

    @Override
    public void configureRepositoryRestConfiguration(RepositoryRestConfiguration repositoryRestConfiguration){
        repositoryRestConfiguration.exposeIdsFor(entityManager.getMetamodel().getEntities().stream().map
                (Type::getJavaType).toArray(Class[]::new));
    }

    @Override
    public void addCorsMappings(CorsRegistry registry){
        registry.addMapping("/**");
    }

}

有角它抛出以下错误：

Access to XMLHttpRequest at 'http://localhost:8080/getPositions' from origin 'http://localhost:4200' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

同时我可以在浏览器中很好地加载URL：http://localhost:8080/getPositions并查看输出。

我的Angular代码是

getAllPositions(): Observable<Position[]> {
    const httpOptions  = {
      headers: new HttpHeaders(
        {'Content-Type': 'application/x-www-form-urlencoded',
          'Access-Control-Allow-Origin': 'http://localhost:4200',
          'Access-Control-Allow-Methods': 'GET,POST,PUT,DELETE,OPTION',
          'Access-Control-Allow-Headers': '*'})
    };
    return this.httpClient.get<Position[]>(this.positionUrl, httpOptions)
      .pipe(
        tap(() => this.log('fetching all Positions')),
        catchError(this.handleError('getAllPositions', []))
      );
  }

请帮助。

Answer 1

从3.1.4.RELEASE版本开始，这是RepositoryRestHandlerMapping中的错误。不过，该问题已在Github上解决，因此希望它将在下一个版本中发布。

如果需要更多信息，请查看https://en.wikipedia.org/w/index.php?title=Vario%20Tessar&action=edit。

更新此问题已在3.1.5.RELEASE

中修复。

Answer 2

问题出在服务器端，因为CORS是由服务器而不是客户端强制执行的，因此Angular代码在其中没有作用，并且在Angular中添加CORS标头将无济于事。

我的假设是您正在端口 8080 上运行后端，并在端口 4200 上运行 Angular 代码>

也许尝试一下：

getAllPositions(): Observable<Position[]> {
    const httpOptions  = {
      headers: new HttpHeaders(
        {'Content-Type': 'application/x-www-form-urlencoded'})
    };
    return this.httpClient.get<Position[]>(this.positionUrl, httpOptions)
      .pipe(
        tap(() => this.log('fetching all Positions')),
        catchError(this.handleError('getAllPositions', []))
      );
  }

还有

@Override
public void addCorsMappings(CorsRegistry registry) {
    registry.addMapping("/getPositions")
        .allowedOrigins("http://localhost:4200")
        .allowedMethods("GET")
}

您需要在端口8080上配置后端服务，以允许来自端口4200的请求-即使两个端口都在本地主机上运行，但不同的端口会触发CORS策略违规，因此您必须明确允许它。

编辑： 也许首先将策略设置为“ *”，最好在全局范围内将其设置为有效，然后再将范围缩小到特定的URL，以确保安全。

    .allowedOrigins("*")

无法为春季启动数据jpa添加CORS支持

2 个答案: