物化OfyService NoClassDefFoundError的App Engine的端点 [英] Objectify OfyService NoClassDefFoundError for app engine endpoint

问题描述

我的Andr​​oid-的AppEngine端点项目设置完全由机器人工作室。因此，我不惹周围的任何东西：我只是让Android的工作室我的AppEngine模块添加到我的Andr​​oid项目。现在，我得到一个 java.lang.NoClassDefFoundError的。我一定要在设置的gradle出头或配置在Android Studio中出头摆脱这种错误的？基本上，当我尝试测试我的应用程序我得到的异常。

My android-appengine-endpoint project is setup entirely by android studio. Therefore I don't mess around with anything: I just let android studio add my AppEngine module to my android project. Now I am getting a java.lang.NoClassDefFoundError. Do I have to set somethings in gradle or configure somethings in android studio to get rid of this error? Basically when I try to test my app I get the exception.

code：

注意：而不是调用的 OFY 我的端点类里面，userDAO的是一个地方，所有的 OFY 数据访问调用的。您可以比较我的code到<一个href=\"http://rominirani.com/2014/08/26/gradle-tutorial-part-9-cloud-endpoints-persistence-android-studio/\"相对=nofollow>本教程

Note: Instead of calling ofy inside my endpoint class, UserDao is a place where all the ofy data access calls are made. You can compare my code to this tutorial

public class UserDao extends OfyService {
    public static void persist(User user) {
        ofy().save().entities(user).now();
    }
    public static User getById(long id) {
        return ofy().load().type(User.class).id(id).now();
    }
    public static List<User> getByTwitterId(Long twitterId) {
        return ofy().load().type(User.class).filter("twitterId", twitterId).list();
    }
}

public class OfyService {
    public OfyService() {}

    static {
        ObjectifyService.register(User.class);
        ObjectifyService.register(Food.class);
        ObjectifyService.register(Pet.class);
    }

    public static Objectify ofy() { return ObjectifyService.ofy(); }

    public static ObjectifyFactory factory() {
        return ObjectifyService.factory();
    }
}

从App Engine的控制台中看到的实际的错误：

The actual error as seen from the App Engine Console:

com.google.api.server.spi.SystemService invokeServiceMethod: exception occurred while calling backed method
java.lang.NoClassDefFoundError: Could not initialize class com.mycompany.server.data.dao.UserDao
    at com.mycompany.server.utils.Authenticator.verifyAccount(Authenticator.java:22)
    at com.mycompany.server.endpoint.server.getFood(server.java:105)
    at sun.reflect.GeneratedMethodAccessor22.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:44)
    at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:359)
    at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:160)
    at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:118)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.googlecode.objectify.ObjectifyFilter.doFilter(ObjectifyFilter.java:48)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:230)
    at com.google.tracing.TraceContext$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 java.lang.Thread.run(Thread.java:745)

每一个岗位我在这里看到的似乎是在谈论 WEB-INF \\ lib目录。那么Android的工作室并没有创造任何lib目录下我的WEB-INF中。因此，无论Android的Studio和App Engine的是来自谷歌。因此，我在这里丧命。

Every post I see here seem to be talking about WEB-INF\lib. Well Android Studio has not created any lib directory inside my WEB-INF. So both Android Studio and App Engine are from Google. Therefore I am at a lost there.

我的的webapp / WEB-INF 中有只有三个文件：

My webapp/WEB-INF has only three files in it:

• 的web.xml


• logging.properties


• 的AppEngine-web.xml中

• web.xml
• logging.properties
• appengine-web.xml

下面是我的情况下，依赖的图像可以帮助：

Here is an image of my dependencies in case it helps:

推荐答案

由于您使用云端点，做到这一点：

Since you are using Cloud Endpoint, do this:

1. 在你的端点类，创建一个构造。


2. 在构造函数中，调用新OfyService（）。

1. In your Endpoint class, create a constructor.
2. In the constructor, call new OfyService().

这可能工作的原因是，你会加载所有的客观化相关类的方式方法需要（客户端进行第一次调用之前即方法）来使用它们。现在你所加载它们，你需要他们权利之前。而在App-Engine类加载器的延迟可能是什么杀了你。可悲的是，你正在使用的结构非常受欢迎，所以大多数人用这种方式：，但也不能保证它会一直工作。这是一个竞争条件的事情。应用引擎可以加载类很慢。幸运（或者不吉利）你，你及早发现问题。人们应该给你一些upvotes为您的痛苦。）

The reason this may work is that you will have loaded all your objectify related classes way way before you need to use them (i.e. way before a client makes a first call). Right now you are loading them right before you need them . And delays in the App-Engine class loader may be what's killing you. The sad thing is, the structure you are using is very popular and so most people use it that way: and yet there is no guarantee that it will always work. It's a race condition thing. App-engine can be very slow to load classes. Lucky (or unlucky) for you, you find the problem early. People should give you some upvotes for your pains :).

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