具有多个调度程序的Spring Java配置 [英] Spring Java Config with Multiple Dispatchers
问题描述
我现在有一些体验Spring，并且还使用了一些纯Java配置web应用程序。但是，这些通常基于一个安静的简单设置：
I've some experience Spring now and also have some pure java config web-apps in use. However, these are usually based on a quiet simple setup:
- 服务/存储库的应用程序配置
- 一个调度员（和一些控制器）的调度程序配置
- （可选）弹簧安全性以保护访问
对于我当前的项目，我需要具有不同配置的单独调度程序上下文。这不是基于XML的配置的问题，因为我们有一个独立于Dispatcher Configuration的专用ContextLoaderListener。但是使用java配置我不确定到目前为止我做的是否正常;）
For my current project I need to have separate dispatcher contexts with different configuration. That's not a problem with the XML based configuration as we have a dedicated ContextLoaderListener that's independent from Dispatcher Configuration. But with java config I'm not sure if what I'm doing is fine so far ;)
这是一个常见的DispatcherConfig：
Here's a common DispatcherConfig:
public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return new class[]{MyAppConfig.class};
}
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class[]{MyDispatcherConfig.class};
}
@Override
protected String[] getServletMappings() {
return new String[]{"/mymapping/*"};
}
@Override
protected String getServletName() {
return "myservlet";
}
}
如上所述，我需要一秒钟（第三，。 ..）调度程序与另一个映射（和视图解析器）。因此，我复制了配置并为getServletName（）添加了（否则两者都将被命名为'dispatcher'，这将导致错误）。第二个配置看起来像这样：
As said, I need a second (third, ...) dispatcher with another mapping (and view resolvers). So, I copied the config and added for both getServletName() (otherwise both will be named as 'dispatcher' which will cause errors). The second config was looking like that:
public class AnotherWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return new class[]{MyAppConfig.class};
}
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class[]{AnotherDispatcherConfig.class};
}
@Override
protected String[] getServletMappings() {
return new String[]{"/another_mapping/*"};
}
@Override
protected String getServletName() {
return "anotherservlet";
}
}
当我像这样使用它时，启动应用程序会导致ContextLoaderListener的问题：
When I use it like this, starting application results in a problem with ContextLoaderListener:
java.lang.IllegalStateException: Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your web.xml!
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:277)
...
所以我从其中一个
AbstractAnnotationConfigDispatcherServletInitializer 中删除了第二个 MyAppConfig.class ，它运行正常。但是，这感觉不是正确的方法;）
So I removed the second MyAppConfig.class return from one of the AbstractAnnotationConfigDispatcherServletInitializer and it works fine. However, that doesn't feel to be the right way ;)
根据我的理解：是否应在一个 AbstractAnnotationConfigDispatcherServletInitializer 中处理所有DispatcherConfig或应该我和我分开了吗？我尝试在一个类中配置它们，但后来我的配置完全混合（所以我认为这不是理想的方式）。
For my understanding: should all DispatcherConfig be handled within one AbstractAnnotationConfigDispatcherServletInitializer or should I separate them as I did? I tried to configure them in one class but then my config was totally mixed (so I believe that's not the desired way).
你如何实现这样的情况？是否可以在 AbstractAnnotationConfigDispatcherServletInitializer 之外的java配置中设置 ContextLoaderListener ？或者我应该创建一个只有root配置的 DefaultServlet ？如何实现该配置的基本接口 WebApplicationInitializer ？
How do you implement such a case? Is it possible to set the ContextLoaderListener in java config outside of the AbstractAnnotationConfigDispatcherServletInitializer? Or should I create a DefaultServlet which has only the root config? What about implementing the base interface of that configuration WebApplicationInitializer?
推荐答案
Mahesh C.展示了正确的道路，但他的实施太有限了。他是对的：你不能直接使用 AbstractAnnotationConfigDispatcherServletInitializer 来表示多个调度程序servlet。但实现应该：
Mahesh C. showed the right path, but his implementation is too limited. He is right on one point : you cannot use directly AbstractAnnotationConfigDispatcherServletInitializer for multiple dispatcher servlet. But the implementation should :
- 创建根应用程序上下文
- 给它一个初始配置并说它应扫描的包
- 为它添加一个ContextListener到servlet上下文
- 然后为每个调度程序servlet
- 创建子应用程序上下文
- 为其提供相同的初始配置和要扫描的包
- 使用上下文创建DispatcherServlet
- 将其添加到servlet上下文
- create a root application context
- gives it an initial configuration and say what packages it should scan
- add a ContextListener for it to the servlet context
- then for each dispatcher servlet
- create a child application context
- gives it the same an initial configuration and packages to scan
- create a DispatcherServlet using the context
- add it to the servlet context
这是一个更完整的实现：
Here is a more complete implementation :
@Override public void onStartup(ServletContext servletContext) throws ServletException { // root context AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext(); rootContext.register(RootConfig.class); // configuration class for root context rootContext.scan("...service", "...dao"); // scan only some packages servletContext.addListener(new ContextLoaderListener(rootContext)); // dispatcher servlet 1 AnnotationConfigWebApplicationContext webContext1 = new AnnotationConfigWebApplicationContext(); webContext1.setParent(rootContext); webContext1.register(WebConfig1.class); // configuration class for servlet 1 webContext1.scan("...web1"); // scan some other packages ServletRegistration.Dynamic dispatcher1 = servletContext.addServlet("dispatcher1", new DispatcherServlet(webContext1)); dispatcher1.setLoadOnStartup(1); dispatcher1.addMapping("/subcontext1"); // dispatcher servlet 2 ... }这样，您可以完全控制哪些bean将在哪个上下文中结束，就像使用XML配置一样。
That way, you have full control on which beans will end in which context, exactly as you would have with XML configuration.
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