在Google App Engine Standard上运行Spring Boot应用程序时出现javax.el.ExpressionFactory错误

Question

无法初始化“javax.el.ExpressionFactory”。检查是否有对类路径的EL依赖项，或者在org.eclipse.jetty.annotations.servletContainerInitializersStarter.doStart(servletContainerInitializersStarter.java:68)在org.eclipse.jetty.util.component.abstractLifecycle.start（abstractLifecycle.java:68)在org.eclipse.jetty.servlet.servlet.servletContextHandler.startContext(servletContextHandler.java:330)在在org.eclipse.jetty.server.handler.contextHandler.doStart（contextHandler.java:778)在org.eclipse.jetty.servlet.servletContext.doStart（servletContextHandler.java:262)在org.eclipse.jetty.webapp.webappContext.doStart（webappContext.java:522)在org.eclipse.jetty.util.component.abstractLifecycle.start（createHandler（AppVersionHandlerMap.java:244)在com.google.apphosting.runtime.jetty9.appversionHandlerMap.gethandler(appversionHandlerMap.java:182)在com.google.apphosting.runtime.jetty9.jettyServletEngineAdapter.ServiceRequest(jettyServletEngineAdapter.java:97)在com.google.apphosting.runtime.javaruntime$requestrunnable.dispatchServletRequest在com.google.apphosting.runtime.javaruntime$nullsandboxrequestrunnable.run(javaruntime.java:589)在com.google.apphosting.runtime.threadgrouppool$poolentry.run(javaruntime.java:745)在com.google.apphosting.runtime.threadgrouppool$poolentry.run(threadgrouppool.java:263)在java.lang.thread.run Configuration“：通过方法”Set Configurers“参数0表示不满足的依赖关系；嵌套异常是org.springframework.beans.factory.UnsatisfiedDependencyException：创建名为“Async Configuration”的bean时出错

然而，只有当我在Google app Engine上运行我的应用程序时，才会出现此错误。如果我在本地打包并运行它，应用程序就会像预期的那样工作。

你知道是什么导致了这个问题吗？谢谢你！

Answer 1

确保您有el依赖项；

    <dependency>
        <groupId>org.glassfish</groupId>
        <artifactId>javax.el</artifactId>
        <version>3.0.1-b08</version>
    </dependency>

还要在AppEngine-web.xml中添加一个env-variables条目；

    <env-variables>
        <env-var name="javax.el.ExpressionFactory" value="com.sun.el.ExpressionFactoryImpl" />
    </env-variables>

并添加文件'meta-inf/services/javax.el.expressionFactory'，其内容如下：

    com.sun.el.ExpressionFactoryImpl