无法获取当前用户：没有可用的RequestContext

Question

使用xsuaa approuter登录名获取登录的用户对象时遇到异常

User currentUser = UserAccessor.getCurrentUser();

我要在不使用GuiceFilter的情况下获取currentUser对象，如果我应用GuiceFilter则会出现以下异常。

任何人请向我建议如何通过GuiceFilter获取UserAccessor.getCurrentUser（）

com.sap.cloud.sdk.cloudplatform.security.user.exception.UserAccessException: Failed to get current user: no RequestContext available. Have you correctly configured a RequestContextServletFilter or have you wrapped your logic in a RequestContextExecutor when executing background tasks that are not triggered by a request?
at com.sap.cloud.sdk.cloudplatform.security.user.AbstractUserFacade.getCurrentUserIfAuthenticated(AbstractUserFacade.java:85)
at com.sap.cloud.sdk.cloudplatform.security.user.AbstractUserFacade.getCurrentUser(AbstractUserFacade.java:135)
at com.sap.cloud.sdk.cloudplatform.security.user.UserAccessor.getCurrentUser(UserAccessor.java:122)
at com.company.HelloWorldServlet2.handleRequest(HelloWorldServlet2.java:35)
at com.company.BaseServlet.doPost(BaseServlet.java:120)
at com.company.BaseServlet.doGet(BaseServlet.java:104)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at com.google.inject.servlet.ServletDefinition.doServiceImpl(ServletDefinition.java:287)
at com.google.inject.servlet.ServletDefinition.doService(ServletDefinition.java:277)
at com.google.inject.servlet.ServletDefinition.service(ServletDefinition.java:182)
at com.google.inject.servlet.ManagedServletPipeline.service(ManagedServletPipeline.java:91)
at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:119)
at com.google.inject.servlet.GuiceFilter$1.call(GuiceFilter.java:133)
at com.google.inject.servlet.GuiceFilter$1.call(GuiceFilter.java:130)
at com.google.inject.servlet.GuiceFilter$Context.call(GuiceFilter.java:203)
at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:130)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:44)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at com.sap.xs.java.valves.ErrorReportValve.invoke(ErrorReportValve.java:66)
at ch.qos.logback.access.tomcat.LogbackValve.invoke(LogbackValve.java:191)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at com.sap.xs.jdbc.datasource.valve.JDBCValve.invoke(JDBCValve.java:62)
at com.sap.xs.security.UserInfoValve.invoke(UserInfoValve.java:19)
at com.sap.xs.statistics.tomcat.valve.RequestTracingValve.invoke(RequestTracingValve.java:43)
at com.sap.xs.logging.catalina.RuntimeInfoValve.invoke(RuntimeInfoValve.java:40)
at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:695)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1136)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:836)

Answer 1

从堆栈跟踪中看，似乎GuiceFilter被调用而RequestContextServletFilter没有被调用。 RequestContextServletFilter初始化RequestContext，这是检索用户信息的前提。

您可以尝试在web.xml文件中显式声明RequestContextServletFilter吗？

Answer 2

从本质上讲，桑德的答案已经是正确的（请接受他的回答）。为了更精确，您在web.xml中的定义必须采用以下方式（之前省略所有其他ServletFilter）：

<!-- other filter go here -->

<filter>
    <filter-name>RequestContextServletFilter</filter-name>
    <filter-class>com.sap.cloud.sdk.cloudplatform.servlet.RequestContextServletFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>RequestContextServletFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

<filter>
    <filter-name>guiceFilter</filter-name>
    <filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>guiceFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

我已经尝试过使用这个最小的无效示例，但该异常消失了。使用ALLOW_MOCKED_AUTH_HEADER：真实的环境变量，将返回一个空用户，这足以证明该过滤器在Guice过滤器之前适用：