Google App Engine上的Spring MVC和REST

前段时间，我写了一篇关于如何使用Spring MVC实现Restful Web API的文章 。阅读我以前的文章以了解它。

在那篇文章中，开发了一个简单的Rest示例。为了测试该应用程序，将文件复制到Web服务器（例如Tomcat ）中，然后返回对字符1的http：// localhost：8080 / RestServer / characters / 1信息的访问。

在当前文章中，我将解释如何将应用程序转换为Google App Engine并使用Maven部署到Google的基础架构中。当然，在这种情况下，我们将部署Rest Spring MVC应用程序，但是可以使用相同的方法将Spring MVC Web应用程序（或使用其他Web框架开发的任何其他应用程序）迁移到GAE。

首先，显然，您应该创建一个Google帐户并注册一个新的应用程序 （记住名称，因为它将在下一步中使用）。之后，您可以开始迁移。

需要进行三个更改，创建定义应用程序名称的appengine-web.xml ；使用Google帐户信息将服务器标记添加到settings.xml，并修改pom.xml以添加GAE插件及其依赖项。

让我们从appengine-web.xml开始。 GAE使用此文件来配置应用程序，并将其创建到WEB-INF目录（与web.xml处于同一级别）。

<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://appengine.google.com/ns/1.0 http://googleappengine.googlecode.com/svn/branches/1.2.1/java/docs/appengine-web.xsd"><application>alexsotoblog</application><version>1</version><system-properties><property name="java.util.logging.config.file" value="WEB-INF/classes/logging.properties"/></system-properties><precompilation-enabled>false</precompilation-enabled><sessions-enabled>true</sessions-enabled>
</appengine-web-app>

最重要的字段是应用程序标签。此标记包含我们应用程序的名称（在您注册新的Google应用程序时定义）。

其他标签包括版本，系统属性和环境变量以及其他配置，例如您是否希望预编译以提高性能或应用程序需要会话。

而且您的项目不再需要修改，现在仅会触摸Maven文件。

在settings.xml中 ，应该添加帐户信息：

<settings xmlns="http://maven.apache.org/SETTINGS/1.1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.1.0 http://maven.apache.org/xsd/settings-1.1.0.xsd"><localRepository>/media/share/maven_repo</localRepository><servers><server><id>appengine.google.com</id><username>my_account@gmail.com</username><password>my_password</password></server></servers></settings>

看到这和在Maven中注册任何其他服务器一样容易。

最后是最繁琐的部分，修改pom.xml 。

首先要添加新属性：

<gae.home>/media/share/maven_repo/com/google/appengine/appengine-java-sdk/1.5.5/appengine-java-sdk-1.5.5</gae.home>
<gaeApplicationName>alexsotoblog</gaeApplicationName>
<gaePluginVersion>0.9.0</gaePluginVersion>
<gae.version>1.5.5</gae.version><!-- Upload to http://test.latest.<applicationName>.appspot.com by default -->
<gae.application.version>test</gae.application.version>

在第一行中，我们定义了Appengine Java SDK的位置。如果已经安装，则在此标记中插入位置，如果没有，则复制此pom的相同位置，然后将maven存储库目录（在我的情况下为/ media / share / maven_repo）更改为您的目录。通常，您的Maven存储库位置为/home/user/.m2/repositories 。 Maven将在部署时为您下载SDK 。

下一步是添加Maven GAE存储库。

<repositories><repository><id>maven-gae-plugin-repo</id><url>http://maven-gae-plugin.googlecode.com/svn/repository</url><name>maven-gae-plugin repository</name></repository>
</repositories><pluginRepositories><pluginRepository><id>maven-gae-plugin-repo</id><name>Maven Google App Engine Repository</name><url>http://maven-gae-plugin.googlecode.com/svn/repository/</url></pluginRepository>
</pluginRepositories>

因为我们的项目是虚拟项目，所以不使用Datanucleus 。对于更复杂的项目，需要使用例如JDO进行数据库访问，应添加下一个依赖项：

<dependency><groupId>javax.jdo</groupId><artifactId>jdo2-api</artifactId><version>2.3-eb</version><exclusions><exclusion><groupId>javax.transaction</groupId><artifactId>transaction-api</artifactId></exclusion></exclusions>
</dependency><dependency><groupId>com.google.appengine.orm</groupId><artifactId>datanucleus-appengine</artifactId><version>1.0.6.final</version>
</dependency><dependency><groupId>org.datanucleus</groupId><artifactId>datanucleus-core</artifactId><version>1.1.5</version><scope>runtime</scope><exclusions><exclusion><groupId>javax.transaction</groupId><artifactId>transaction-api</artifactId></exclusion></exclusions>
</dependency><dependency><groupId>com.google.appengine</groupId><artifactId>geronimo-jta_1.1_spec</artifactId><version>1.1.1</version><scope>runtime</scope>
</dependency><dependency><groupId>com.google.appengine</groupId><artifactId>geronimo-jpa_3.0_spec</artifactId><version>1.1.1</version><scope>runtime</scope>
</dependency>

如果您使用的是Datanucleus ，则应注册maven-datanucleus-plugin 。请注意根据您的项目正确配置它。

<plugin><groupId>org.datanucleus</groupId><artifactId>maven-datanucleus-plugin</artifactId><version>1.1.4</version><configuration><!--Make sure this path contains your persistentclasses!--><mappingIncludes>**/model/*.class</mappingIncludes><verbose>true</verbose><enhancerName>ASM</enhancerName><api>JDO</api></configuration><executions><execution><phase>compile</phase><goals><goal>enhance</goal></goals></execution></executions><dependencies><dependency><groupId>org.datanucleus</groupId><artifactId>datanucleus-core</artifactId><version>1.1.5</version><exclusions><exclusion><groupId>javax.transaction</groupId><artifactId>transaction-api</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.datanucleus</groupId><artifactId>datanucleus-rdbms</artifactId><version>1.1.5</version></dependency><dependency><groupId>org.datanucleus</groupId><artifactId>datanucleus-enhancer</artifactId><version>1.1.5</version></dependency></dependencies>
</plugin>

现在，添加了Google App Engine依赖项。

<dependency><groupId>com.google.appengine</groupId><artifactId>appengine-api-1.0-sdk</artifactId><version>${gae.version}</version>
</dependency><dependency><groupId>com.google.appengine</groupId><artifactId>appengine-tools-api</artifactId><version>1.3.7</version>
</dependency>

然后，如果您想测试GAE 功能（在我们的虚拟项目中未使用），则添加下一个GAE库：

<dependency><groupId>com.google.appengine</groupId><artifactId>appengine-api-labs</artifactId><version>${gae.version}</version><scope>test</scope>
</dependency><dependency><groupId>com.google.appengine</groupId><artifactId>appengine-api-stubs</artifactId><version>${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>

接下来的更改是对maven-war-plugin的修改，其中将appengine-web.xml包含到生成的包中：

<plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-war-plugin</artifactId><configuration><webResources><resource><directory>src/main/webapp</directory><filtering>true</filtering><includes><include>**/appengine-web.xml</include></includes></resource></webResources></configuration>
</plugin>

最后添加maven-gae-plugin并将其配置为将应用程序上传到appspot 。

<plugin><groupId>net.kindleit</groupId><artifactId>maven-gae-plugin</artifactId><version>${gaePluginVersion}</version><configuration><serverId>appengine.google.com</serverId></configuration><dependencies><dependency><groupId>net.kindleit</groupId><artifactId>gae-runtime</artifactId><version>${gae.version}</version><type>pom</type></dependency></dependencies>
</plugin>

看到<serviceId>标记包含先前在settings.xml文件中定义的服务器名称。

另外，如果您使用的是maven-release-plugin ，则可以在release：perform目标期间将应用程序自动上传到appspot ：

<plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-release-plugin</artifactId><version>2.2.1</version><configuration><goals>gae:deploy</goals></configuration>
</plugin>

现在运行gae：deploy目标。如果您已经安装了Appengine Java SDK ，那么您的应用程序将被上传到您的GAE网站。但是，如果这是您第一次运行该插件，则会收到错误消息。不要惊慌，发生此错误是因为Maven插件未在您在<gae.home>标记中指定的目录中找到Appengine SDK 。但是，如果您已将gae.home位置配置到本地Maven存储库中，只需运行gae：unpack目标，即可正确安装SDK ，因此当您重新运行gae：deploy时，您的应用程序将上传到Google基础架构中。

在后例子中，你可以去http://alexsotoblog.appspot.com/characters/1http://alexsotoblog.appspot.com/characters/1和JSON格式的字符信息显示到浏览器中。

正如我在文章开头提到的那样，相同的过程可以用于任何Web应用程序，而不仅仅是Spring Rest MVC 。

由于教学目的，对应用程序pom进行了所有修改。我的建议是，您要使用GAE相关标签创建父pom ，因此必须上传到Google App Engine的每个项目都来自同一pom文件。

我希望您发现这篇文章有用。

本周，我在devoxx ，在那与我见面；）我将在17日（星期四）13:00发表有关通过聚合和最小化加速Javascript和CSS下载时间的演讲。

完整的pom文件：

<?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.springframework</groupId><artifactId>rest</artifactId><name>Rest</name><packaging>war</packaging><version>1.0.0-BUILD-SNAPSHOT</version><properties><java-version>1.6</java-version><org.springframework-version>3.0.4.RELEASE</org.springframework-version><org.aspectj-version>1.6.9</org.aspectj-version><org.slf4j-version>1.5.10</org.slf4j-version><!-- Specify AppEngine version for your project. It should match SDK version pointed to by ${gae.home} property (Typically, one used by your Eclipse plug-in) --><gae.home>/home/alex/.m2/repository/com/google/appengine/appengine-java-sdk/1.5.5/appengine-java-sdk-1.5.5</gae.home><gaeApplicationName>alexsotoblog</gaeApplicationName><gaePluginVersion>0.9.0</gaePluginVersion><gae.version>1.5.5</gae.version><!-- Upload to http://test.latest.<applicationName>.appspot.com by default --><gae.application.version>test</gae.application.version></properties><dependencies><!-- Rest --><dependency><groupId>com.sun.xml.bind</groupId><artifactId>jaxb-impl</artifactId><version>2.2.4-1</version></dependency><dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-core-lgpl</artifactId><version>1.8.5</version></dependency><dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-mapper-lgpl</artifactId><version>1.8.5</version></dependency><!-- GAE libraries for local testing as described here: http://code.google.com/appengine/docs/java/howto/unittesting.html --><dependency><groupId>com.google.appengine</groupId><artifactId>appengine-api-labs</artifactId><version>${gae.version}</version><scope>test</scope></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><dependency><groupId>com.google.appengine</groupId><artifactId>appengine-api-1.0-sdk</artifactId><version>${gae.version}</version></dependency><dependency><groupId>com.google.appengine</groupId><artifactId>appengine-tools-api</artifactId><version>1.3.7</version></dependency><!-- Spring --><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${org.springframework-version}</version><exclusions><!-- Exclude Commons Logging in favor of SLF4j --><exclusion><groupId>commons-logging</groupId><artifactId>commons-logging</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${org.springframework-version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-oxm</artifactId><version>${org.springframework-version}</version></dependency><!-- AspectJ --><dependency><groupId>org.aspectj</groupId><artifactId>aspectjrt</artifactId><version>${org.aspectj-version}</version></dependency><!-- Logging --><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>${org.slf4j-version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>jcl-over-slf4j</artifactId><version>${org.slf4j-version}</version><scope>runtime</scope></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>${org.slf4j-version}</version><scope>runtime</scope></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.15</version><exclusions><exclusion><groupId>javax.mail</groupId><artifactId>mail</artifactId></exclusion><exclusion><groupId>javax.jms</groupId><artifactId>jms</artifactId></exclusion><exclusion><groupId>com.sun.jdmk</groupId><artifactId>jmxtools</artifactId></exclusion><exclusion><groupId>com.sun.jmx</groupId><artifactId>jmxri</artifactId></exclusion></exclusions><scope>runtime</scope></dependency><!-- @Inject --><dependency><groupId>javax.inject</groupId><artifactId>javax.inject</artifactId><version>1</version></dependency><!-- Servlet --><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>2.1</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><!-- Test --><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.7</version><scope>test</scope></dependency></dependencies><repositories><!-- For testing against latest Spring snapshots --><repository><id>org.springframework.maven.snapshot</id><name>Spring Maven Snapshot Repository</name><url>http://maven.springframework.org/snapshot</url><releases><enabled>false</enabled></releases><snapshots><enabled>true</enabled></snapshots></repository><!-- For developing against latest Spring milestones --><repository><id>org.springframework.maven.milestone</id><name>Spring Maven Milestone Repository</name><url>http://maven.springframework.org/milestone</url><snapshots><enabled>false</enabled></snapshots></repository><!-- GAE repositories --><repository><id>maven-gae-plugin-repo</id><url>http://maven-gae-plugin.googlecode.com/svn/repository</url><name>maven-gae-plugin repository</name></repository></repositories><pluginRepositories><pluginRepository><id>maven-gae-plugin-repo</id><name>Maven Google App Engine Repository</name><url>http://maven-gae-plugin.googlecode.com/svn/repository/</url></pluginRepository></pluginRepositories><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>${java-version}</source><target>${java-version}</target></configuration></plugin><!-- Adding appengine-web into war --><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-war-plugin</artifactId><configuration><webResources><resource><directory>src/main/webapp</directory><filtering>true</filtering><includes><include>**/appengine-web.xml</include></includes></resource></webResources><warName>abc</warName></configuration></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-dependency-plugin</artifactId><executions><execution><id>install</id><phase>install</phase><goals><goal>sources</goal></goals></execution></executions></plugin><plugin><groupId>org.codehaus.mojo</groupId><artifactId>aspectj-maven-plugin</artifactId><!-- Have to use version 1.2 since version 1.3 does not appear to work with ITDs --><version>1.2</version><dependencies><!-- You must use Maven 2.0.9 or above or these are ignored (see MNG-2972) --><dependency><groupId>org.aspectj</groupId><artifactId>aspectjrt</artifactId><version>${org.aspectj-version}</version></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjtools</artifactId><version>${org.aspectj-version}</version></dependency></dependencies><executions><execution><goals><goal>compile</goal><goal>test-compile</goal></goals></execution></executions><configuration><outxml>true</outxml><source>${java-version}</source><target>${java-version}</target></configuration></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-surefire-plugin</artifactId><configuration><junitArtifactName>junit:junit</junitArtifactName></configuration></plugin><plugin><groupId>org.codehaus.mojo</groupId><artifactId>tomcat-maven-plugin</artifactId><version>1.0-beta-1</version></plugin><!-- The actual maven-gae-plugin. Type "mvn gae:run" to run project, "mvn gae:deploy" to upload to GAE. --><plugin><groupId>net.kindleit</groupId><artifactId>maven-gae-plugin</artifactId><version>${gaePluginVersion}</version><configuration><serverId>appengine.google.com</serverId></configuration><dependencies><dependency><groupId>net.kindleit</groupId><artifactId>gae-runtime</artifactId><version>${gae.version}</version><type>pom</type></dependency></dependencies></plugin></plugins></build>
</project>

下载代码。
音乐： http ： //www.youtube.com/watch？v = Nba3Tr_GLZU

参考：来自JCG合作伙伴 Alex Soto 在Google App Engine上的Spring MVC和REST，来自One Jar To Rule All All博客。

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