App Engine(突然)告诉我我的 Objectify 设置不正确。它之前是有效的，我确实在我的 web.xml 中有 Objectify Filter。

这是我日志中的完整堆栈跟踪:

javax.servlet.ServletContext log: unavailable
java.lang.IllegalStateException: You have not started an Objectify context.
                                 You are probably missing the ObjectifyFilter.
                                 If you are not running in the context of an http request, see the ObjectifyService.run() method.
    at com.googlecode.objectify.ObjectifyService.ofy(ObjectifyService.java:44)
    at com.mydomain.gae.defaultmodule.MyObject.loadEverything(MyObject.java:21)
    at com.mydomain.gae.defaultmodule.MyServlet.init(MyServlet.java:40)
    at javax.servlet.GenericServlet.init(GenericServlet.java:212)
    at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:440)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:263)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:206)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:179)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:136)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:469)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:256)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235)
    at java.lang.Thread.run(Thread.java:745)

这是我的 web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <listener>
        <listener-class>
            com.mydomain.gae.defaultmodule.Initializer
        </listener-class>
    </listener>

    <servlet>
        <servlet-name>MyServlet</servlet-name>
        <servlet-class>com.mydomain.gae.defaultmodule.MyServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>MyServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>ObjectifyFilter</filter-name>
        <filter-class>com.googlecode.objectify.ObjectifyFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>ObjectifyFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

...然后是代码:

public class Initializer implements ServletContextListener {

    @Override
    public void contextInitialized(@Nonnull final ServletContextEvent SCE) {
        ObjectifyFactory oFactory = ObjectifyService.factory();
        oFactory.register(MyEntity.class);
        oFactory.register(MyOtherEntity.class);
        oFactory.begin();
    }
}

public final class MyServlet extends HttpServlet {

    private MyObject = myObj;

    @Override
    public void init() throws ServletException {
        myObj = new MyObject();
        myObj.loadEverything();
    }
}

public class MyObject extends MyOtherObject {

    public void loadEverything() {
        for (MyEntity me : ofy().load().type(MyEntity.class).list()) {
            // Do very important things.
        }
    }
}

一旦到达 ofy().load().type(MyEntity.class).list() 就会抛出 IllegalStateException。此代码以前有效。我不明白为什么这突然在我面前爆炸了，因为在这次爆炸之前，这里共享的代码都没有改变。

如果有人有任何想法可以让我朝着正确的方向前进，我 100% 有兴趣听取他们的意见。

最佳答案

过滤器适用于请求。您的 servlet init 方法未在请求的上下文中调用，因此 ObjectifyFilter 未运行 - 请注意它不在您的堆栈跟踪中。

去掉 contextInitialized() 中的 oFactory.begin()，这不是该方法的正确用法。

如果您想在您的 servlet init() 中使用 Objectify，请在 ObjectifyService.run() 中运行您的代码:

ObjectifyService.run(new VoidWork() {
    public void vrun() {
        myObj = new MyObject();
        myObj.loadEverything();
    }
});

这将以与过滤器相同的方式设置和拆除 Objectify 上下文。

关于java - Objectify 上下文未启动/缺少 ObjectifyFilter，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34476401/