每次我将 GWT 应用程序部署到 appengine 并尝试访问它时，我都会看到白色的加载屏幕，然后大约 20-30 秒后我会收到以下消息：
我使用 Maven 与gwt-maven-插件 and appengine-maven-插件。使用部署maven-gae-插件给出相同的结果。
如果我切换回使用 2.6.1 版本的 gwt 和 gwt-maven-plugin，它部署正常，所以这似乎与自动开发模式启动器有关。
<build>
<outputDirectory>${webappDirectory}/WEB-INF/classes</outputDirectory>
<resources>
<resource>
<directory>src/main/resources</directory>
</resource>
<resource>
<directory>src/main/super</directory>
</resource>
<resource>
<directory>${project.build.directory}/generated-sources/apt</directory>
</resource>
<resource>
<directory>${project.build.directory}/generated-sources/gwt</directory>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${target.jdk}</source>
<target>${target.jdk}</target>
<encoding>${project.build.sourceEncoding}</encoding>
<proc>none</proc>
</configuration>
</plugin>
<!-- JUnit Testing - skip *.GwtTest cases -->
<!-- 'mvn test' - runs the Jukito tests -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
<configuration>
<includes>
<include>**/*Test.java</include>
</includes>
<excludes>
<exclude>**/*GwtTest.java</exclude>
<exclude>**/*JUnitTest.java</exclude>
</excludes>
</configuration>
</plugin>
<!-- GWT -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>${gwt-maven-plugin.version}</version>
<configuration>
<strict>true</strict>
<testTimeOut>180</testTimeOut>
<!-- With multiple tests use GwtTestSuite.java for speed -->
<includes>**/*GwtTest.java</includes>
<mode>htmlunit</mode>
<extraJvmArgs>-Xss1024k -Xmx2048M -XX:MaxPermSize=512M</extraJvmArgs>
<logLevel>INFO</logLevel>
<style>PRETTY</style>
<copyWebapp>true</copyWebapp>
<hostedWebapp>${webappDirectory}</hostedWebapp>
<server>com.google.appengine.tools.development.gwt.AppEngineLauncher</server>
<appEngineVersion>${gae.version}</appEngineVersion>
<appEngineHome>${gae.home}</appEngineHome>
<extraJvmArgs>-Dappengine.sdk.root=${gae.home}</extraJvmArgs>
<extraJvmArgs>-Ddatastore.default_high_rep_job_policy_unapplied_job_pct=20</extraJvmArgs>
<port>8888</port>
<runTarget>Project.html</runTarget>
<modules>
<module>com.utilitiessavings.usavappv7.Project</module>
</modules>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>test</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Google App Engine Deployment -->
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>${gae.version}</version>
<configuration>
<enableJarSplitting>true</enableJarSplitting>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<!-- Google Web Toolkit dependencies -->
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>${gwt.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-servlet</artifactId>
<version>${gwt.version}</version>
<scope>runtime</scope>
</dependency>
<!-- Google App Engine dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${gae.version}</version>
</dependency>
<!-- Testing -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-labs</artifactId>
<version>${gae.version}</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${gae.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${gae.version}</version>
<scope>test</scope>
</dependency>
<!-- Persistence dependencies -->
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>persistence-api</artifactId>
<version>${persistence-api.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.objectify</groupId>
<artifactId>objectify</artifactId>
<version>${objectify.version}</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>${javax.validation.version}</version>
</dependency>
<!-- Other dependencies -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>${servlet-api.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
</dependencies>
<add-linker name="xsiframe" />
（尝试删除这一行但仍然得到相同的结果）
月食 (4.4.1)
Maven 3.2.3（3.2.1 嵌入式）
m2eclipse 1.5.0
gwt:compile尝试通过将 nocache.js 文件的时间戳与源文件的时间戳进行比较来“增量”工作，如果它认为输出是最新的，则跳过 GWT 编译。这是易碎的尽管。gwt:run（没有<superDevMode>false</superDevMode>; and gwt:run-codeserver with launcherDir）将使用 SuperDevMode 特定版本覆盖 nocache.js，这可能会导致gwt:compile跳过编译。
要点是：在部署或“发布”时，请确保首先运行mvn clean or force gwt:compile跑过去-Dgwt.compiler.force到马文。