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java - Spring 3.1 WebApplicationInitializer & Embedded Jetty 8 AnnotationConfiguration

转载 作者:IT老高 更新时间:2023-10-28 20:57:58 25 4
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我正在尝试使用 Spring 3.1 和嵌入式 Jetty 8 服务器创建一个没有任何 XML 配置的简单 webapp。

但是,我很难让 Jetty 识别我的 Spring WebApplicationInitializer 接口(interface)的实现。

项目结构:

src
+- main
+- java
| +- JettyServer.java
| +- Initializer.java
|
+- webapp
+- web.xml (objective is to remove this - see below).

上面的Initializer类是WebApplicationInitializer的简单实现:

import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.springframework.web.WebApplicationInitializer;

public class Initializer implements WebApplicationInitializer {

@Override
public void onStartup(ServletContext servletContext) throws ServletException {
System.out.println("onStartup");
}
}

同样,JettyServer 是嵌入式 Jetty 服务器的简单实现:

import org.eclipse.jetty.annotations.AnnotationConfiguration;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.webapp.Configuration;
import org.eclipse.jetty.webapp.WebAppContext;

public class JettyServer {

public static void main(String[] args) throws Exception {

Server server = new Server(8080);

WebAppContext webAppContext = new WebAppContext();
webAppContext.setResourceBase("src/main/webapp");
webAppContext.setContextPath("/");
webAppContext.setConfigurations(new Configuration[] { new AnnotationConfiguration() });
webAppContext.setParentLoaderPriority(true);

server.setHandler(webAppContext);
server.start();
server.join();
}
}

我的理解是,Jetty 在启动时会使用 AnnotationConfiguration 来扫描 ServletContainerInitializer 的注释实现;它应该找到 Initializer 并将其连接到...

但是,当我(从 Eclipse 中)启动 Jetty 服务器时,我在命令行上看到以下内容:

2012-11-04 16:59:04.552:INFO:oejs.Server:jetty-8.1.7.v20120910
2012-11-04 16:59:05.046:INFO:/:No Spring WebApplicationInitializer types detected on classpath
2012-11-04 16:59:05.046:INFO:oejsh.ContextHandler:started o.e.j.w.WebAppContext{/,file:/Users/duncan/Coding/spring-mvc-embedded-jetty-test/src/main/webapp/}
2012-11-04 16:59:05.117:INFO:oejs.AbstractConnector:Started SelectChannelConnector@0.0.0.0:8080

重要的是:

No Spring WebApplicationInitializer types detected on classpath

请注意,src/main/java 在 Eclipse 中被定义为源文件夹,因此应该位于类路径中。另请注意,Dynamic Web Module Facet 设置为 3.0。

我确信有一个简单的解释,但我很难只见树木不见森林!我怀疑关键在于以下行:

...
webAppContext.setResourceBase("src/main/webapp");
...

这对于使用 web.xml 的 2.5 servlet 是有意义的(见下文),但是使用 AnnotationConfiguration 时应该是什么?

注意:如果我将配置更改为以下内容,一切都会正确启动:

...
webAppContext.setConfigurations(new Configuration[] { new WebXmlConfiguration() });
...

在这种情况下,它会在 src/main/webapp 下找到 web.xml 并使用它通过 DispatcherServlet 和 < em>AnnotationConfigWebApplicationContext 以通常的方式(完全绕过上面的 WebApplicationInitializer 实现)。

这感觉很像一个类路径问题,但我很难理解 Jetty 如何将自己与 WebApplicationInitializer 的实现联系起来 - 任何建议都将不胜感激!

有关信息,我正在使用以下内容:

Spring 3.1.1 jetty 8.1.7 STS 3.1.0

最佳答案

问题是Jetty的AnnotationConfiguration类不扫描classpath下的非jar资源(WEB-INF/classes下除外)。

如果我注册 AnnotationConfiguration 的子类,它会找到我的 WebApplicationInitializer,它会覆盖 configure(WebAppContext) 以另外扫描主机类路径到容器和 web-inf 位置。

大多数子类(可悲的是)从父类复制粘贴。它包括:

  • configure 方法末尾的额外解析调用(parseHostClassPath);
  • parseHostClassPath 方法主要是从AnnotationConfigurationparseWebInfClasses;
  • 获取第一个非 jar URL 的 getHostClassPathResource 方法来自类加载器(至少对我来说,这是我的文件 urleclipse 中的类路径)。

我使用的 Jetty (8.1.7.v20120910) 和 Spring (3.1.2_RELEASE) 版本略有不同,但我想同样的解决方案也可以。

编辑:我在 github 中创建了一个工作示例项目,并进行了一些修改(下面的代码在 Eclipse 中可以正常工作,但在阴影 jar 中运行时却不行)-https://github.com/steveliles/jetty-embedded-spring-mvc-noxml

在 OP 的 JettyServer 类中,必要的更改将第 15 行替换为:

webAppContext.setConfigurations (new Configuration []
{
new AnnotationConfiguration()
{
@Override
public void configure(WebAppContext context) throws Exception
{
boolean metadataComplete = context.getMetaData().isMetaDataComplete();
context.addDecorator(new AnnotationDecorator(context));

AnnotationParser parser = null;
if (!metadataComplete)
{
if (context.getServletContext().getEffectiveMajorVersion() >= 3 || context.isConfigurationDiscovered())
{
parser = createAnnotationParser();
parser.registerAnnotationHandler("javax.servlet.annotation.WebServlet", new WebServletAnnotationHandler(context));
parser.registerAnnotationHandler("javax.servlet.annotation.WebFilter", new WebFilterAnnotationHandler(context));
parser.registerAnnotationHandler("javax.servlet.annotation.WebListener", new WebListenerAnnotationHandler(context));
}
}

List<ServletContainerInitializer> nonExcludedInitializers = getNonExcludedInitializers(context);
parser = registerServletContainerInitializerAnnotationHandlers(context, parser, nonExcludedInitializers);

if (parser != null)
{
parseContainerPath(context, parser);
parseWebInfClasses(context, parser);
parseWebInfLib (context, parser);
parseHostClassPath(context, parser);
}
}

private void parseHostClassPath(final WebAppContext context, AnnotationParser parser) throws Exception
{
clearAnnotationList(parser.getAnnotationHandlers());
Resource resource = getHostClassPathResource(getClass().getClassLoader());
if (resource == null)
return;

parser.parse(resource, new ClassNameResolver()
{
public boolean isExcluded (String name)
{
if (context.isSystemClass(name)) return true;
if (context.isServerClass(name)) return false;
return false;
}

public boolean shouldOverride (String name)
{
//looking at webapp classpath, found already-parsed class of same name - did it come from system or duplicate in webapp?
if (context.isParentLoaderPriority())
return false;
return true;
}
});

//TODO - where to set the annotations discovered from WEB-INF/classes?
List<DiscoveredAnnotation> annotations = new ArrayList<DiscoveredAnnotation>();
gatherAnnotations(annotations, parser.getAnnotationHandlers());
context.getMetaData().addDiscoveredAnnotations (annotations);
}

private Resource getHostClassPathResource(ClassLoader loader) throws IOException
{
if (loader instanceof URLClassLoader)
{
URL[] urls = ((URLClassLoader)loader).getURLs();
for (URL url : urls)
if (url.getProtocol().startsWith("file"))
return Resource.newResource(url);
}
return null;
}
},
});

更新:Jetty 8.1.8 引入了与上述代码不兼容的内部更改。对于 8.1.8,以下似乎有效:

webAppContext.setConfigurations (new Configuration []
{
// This is necessary because Jetty out-of-the-box does not scan
// the classpath of your project in Eclipse, so it doesn't find
// your WebAppInitializer.
new AnnotationConfiguration()
{
@Override
public void configure(WebAppContext context) throws Exception {
boolean metadataComplete = context.getMetaData().isMetaDataComplete();
context.addDecorator(new AnnotationDecorator(context));


//Even if metadata is complete, we still need to scan for ServletContainerInitializers - if there are any
AnnotationParser parser = null;
if (!metadataComplete)
{
//If metadata isn't complete, if this is a servlet 3 webapp or isConfigDiscovered is true, we need to search for annotations
if (context.getServletContext().getEffectiveMajorVersion() >= 3 || context.isConfigurationDiscovered())
{
_discoverableAnnotationHandlers.add(new WebServletAnnotationHandler(context));
_discoverableAnnotationHandlers.add(new WebFilterAnnotationHandler(context));
_discoverableAnnotationHandlers.add(new WebListenerAnnotationHandler(context));
}
}

//Regardless of metadata, if there are any ServletContainerInitializers with @HandlesTypes, then we need to scan all the
//classes so we can call their onStartup() methods correctly
createServletContainerInitializerAnnotationHandlers(context, getNonExcludedInitializers(context));

if (!_discoverableAnnotationHandlers.isEmpty() || _classInheritanceHandler != null || !_containerInitializerAnnotationHandlers.isEmpty())
{
parser = createAnnotationParser();

parse(context, parser);

for (DiscoverableAnnotationHandler h:_discoverableAnnotationHandlers)
context.getMetaData().addDiscoveredAnnotations(((AbstractDiscoverableAnnotationHandler)h).getAnnotationList());
}

}

private void parse(final WebAppContext context, AnnotationParser parser) throws Exception
{
List<Resource> _resources = getResources(getClass().getClassLoader());

for (Resource _resource : _resources)
{
if (_resource == null)
return;

parser.clearHandlers();
for (DiscoverableAnnotationHandler h:_discoverableAnnotationHandlers)
{
if (h instanceof AbstractDiscoverableAnnotationHandler)
((AbstractDiscoverableAnnotationHandler)h).setResource(null); //
}
parser.registerHandlers(_discoverableAnnotationHandlers);
parser.registerHandler(_classInheritanceHandler);
parser.registerHandlers(_containerInitializerAnnotationHandlers);

parser.parse(_resource,
new ClassNameResolver()
{
public boolean isExcluded (String name)
{
if (context.isSystemClass(name)) return true;
if (context.isServerClass(name)) return false;
return false;
}

public boolean shouldOverride (String name)
{
//looking at webapp classpath, found already-parsed class of same name - did it come from system or duplicate in webapp?
if (context.isParentLoaderPriority())
return false;
return true;
}
});
}
}

private List<Resource> getResources(ClassLoader aLoader) throws IOException
{
if (aLoader instanceof URLClassLoader)
{
List<Resource> _result = new ArrayList<Resource>();
URL[] _urls = ((URLClassLoader)aLoader).getURLs();
for (URL _url : _urls)
_result.add(Resource.newResource(_url));

return _result;
}
return Collections.emptyList();
}
}
});

关于java - Spring 3.1 WebApplicationInitializer & Embedded Jetty 8 AnnotationConfiguration,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13222071/

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