java - 带有 Objectify 的基本 GAE 应用程序失败

Question

我使用 Eclipse IDE for Java Developers 4.7.3 通过 Objectify 创建了一个简单的 Google App Engine 标准应用程序。当我部署应用程序并调用 Web 服务时，出现 java.lang.NoClassDefFoundError: Could not initialize class com.googlecode.objectify.ObjectifyService。我究竟做错了什么？以下是重现此错误的步骤:

1. 运行 Eclipse
2. 从 Google Cloud Platform 菜单中，选择 Google App Engine Standard 标准 Java 项目
3. 在项目名称框中，输入项目名称(例如 ObjectifyTest)
4. 在 Java 版本框中，选择 Java 8、Servlet 3.1
5. 选中“创建为 Maven 项目”框
6. 在组 ID 框中，输入组 ID(例如 com.pushpin.objectifytest)
7. 在工件 ID 框中，输入工件 ID(例如 objectifytest)
8. 选中“Google Cloud Endpoints”框
9. 选中“对象化”框
10. 点击完成
11. 打开 web.xml 文件并添加 https://github.com/objectify/objectify/wiki/Setup 中的 ObjectifyFilter
12. 从 Google Cloud Platform 菜单中选择“部署到 App Engine Standard”
13. 点击一个项目(或创建一个新项目然后刷新)
14. 点击部署
15. 调用 servlet(例如通过打开 https://pushpin-objectify-test.appspot.com/hello)
16. 注意 500 服务器错误
17. 检查日志
18. 请注意 java.lang.NoClassDefFoundError:无法初始化类 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。

也就是说，尝试删除 <scope>provided<scope> appengine-api-1.0-sdk 依赖项的 pom.xml 标记。同时将 appengine-api-1.0-sdk 升级到 1.9.63