具有 Objectify 的基本 GAE 应用程序失败

Question

我使用 Eclipse IDE for Java Developers 4.7.3 创建了一个带有 Objectify 的基本 Google App Engine 标准应用程序。当我部署应用程序并调用 Web 服务时，我得到 java.lang.NoClassDefFoundError：无法初始化 class com.googlecode.objectify.ObjectifyService。我究竟做错了什么？以下是重现此错误的步骤：

运行日食
从 Google 云平台菜单中，选择 Google App Engine 标准标准 Java 项目
在项目名称框中，键入项目名称（例如 ObjectifyTest）
在Java版本框中，选择Java 8、Servlet 3.1
选中创建为 Maven 项目框
在组 ID 框中，输入组 ID（例如 com.pushpin.objectifytest）
在工件 ID 框中，输入工件 ID（例如 objectifytest）
选中 Google 云端点框
选中对象化框
点击完成
打开 web.xml 文件并从 https://github.com/objectify/objectify/wiki/Setup
从 Google 云平台菜单中，选择部署到 App Engine 标准
单击一个项目（或创建一个新项目然后刷新）
点击部署
调用 servlet（例如通过打开 https://pushpin-objectify-test.appspot.com/hello）
注意 500 服务器错误
查看日志
注意 java.lang.NoClassDefFoundError：无法初始化 class com.googlecode.objectify.ObjectifyService

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">
    <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>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

这是我的 pom.xml:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <packaging>war</packaging>
  <version>0.1.0-SNAPSHOT</version>

  <groupId>com.pushpin.objectifytest</groupId>
  <artifactId>objectifytest</artifactId>

  <properties>
    <appengine.maven.plugin.version>1.3.1</appengine.maven.plugin.version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
  </properties>

  <prerequisites>
    <maven>3.3.9</maven>
  </prerequisites>

  <dependencies>
    <!-- Compile/runtime dependencies -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>com.google.appengine</groupId>
      <artifactId>appengine-api-1.0-sdk</artifactId>
      <version>1.9.57</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <!-- Test Dependencies -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.google.endpoints</groupId>
      <artifactId>endpoints-framework</artifactId>
      <version>2.0.13</version>
    </dependency>
    <dependency>
      <groupId>com.googlecode.objectify</groupId>
      <artifactId>objectify</artifactId>
      <version>5.1.22</version>
    </dependency>
  </dependencies>

  <build>
    <!-- for hot reload of the web application-->
    <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>versions-maven-plugin</artifactId>
        <version>2.3</version>
        <executions>
          <execution>
            <phase>compile</phase>
            <goals>
              <goal>display-dependency-updates</goal>
              <goal>display-plugin-updates</goal>
            </goals>
          </execution>
        </executions>
      </plugin>

      <plugin>
        <groupId>com.google.cloud.tools</groupId>
        <artifactId>appengine-maven-plugin</artifactId>
        <version>${appengine.maven.plugin.version}</version>
      </plugin>
    </plugins>
  </build>
</project>

这是我的 HelloAppEngine.java 文件：

package com.pushpin.objectifytest;

import java.io.IOException;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(
    name = "HelloAppEngine",
    urlPatterns = {"/hello"}
)
public class HelloAppEngine extends HttpServlet {

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws IOException {

    response.setContentType("text/plain");
    response.setCharacterEncoding("UTF-8");

    response.getWriter().print("Hello App Engine! 1a");

  }
}

这是堆栈跟踪：

com.google.apphosting.runtime.jetty9.JettyLogger warn: Error for /hello (JettyLogger.java:29)
java.lang.NoClassDefFoundError: Could not initialize class com.googlecode.objectify.ObjectifyService
    at com.googlecode.objectify.ObjectifyFilter.doFilter(ObjectifyFilter.java:47)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
    at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
    at com.google.apphosting.runtime.jetty9.SaveSessionFilter.doFilter(SaveSessionFilter.java:37)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
    at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:48)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:582)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at com.google.apphosting.runtime.jetty9.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:297)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
    at org.eclipse.jetty.server.Server.handle(Server.java:534)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320)
    at com.google.apphosting.runtime.jetty9.RpcConnection.handle(RpcConnection.java:202)
    at com.google.apphosting.runtime.jetty9.RpcConnector.serviceRequest(RpcConnector.java:81)
    at com.google.apphosting.runtime.jetty9.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:108)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.dispatchServletRequest(JavaRuntime.java:680)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.dispatchRequest(JavaRuntime.java:642)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:612)
    at com.google.apphosting.runtime.JavaRuntime$NullSandboxRequestRunnable.run(JavaRuntime.java:806)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:274)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

这听起来像 https://github.com/GoogleCloudPlatform/google-cloud-eclipse/issues/2972

导致的服务器端更改已回滚；按照上面的步骤 1-15，我无法重现它。

就是说，尝试从 pom.xml 中删除 appengine-api-1.0-sdk 依赖项的 <scope>provided<scope> 标记。同时升级 appengine-api-1.0-sdk 到 1.9.63

具有 Objectify 的基本 GAE 应用程序失败

Bare bones GAE app with Objectify fails

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