java Spring MVC 和 Servlets 3.0 - 你还需要 web.xml 吗？

Spring MVC and Servlets 3.0 - Do you still need web.xml?

提问by Sotirios Delimanolis

In a typical Spring MVC web app, you would declare the DispatcherServletin web.xmllike so

在典型的 Spring MVC Web 应用程序中，您可以像这样声明DispatcherServletinweb.xml

<!-- MVC Servlet -->
<servlet>
    <servlet-name>sample</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>  
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>sample</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

Along with listeners, filters, etc.

连同侦听器、过滤器等。

With servlet-api 3.0, you can declare your servlets with the annotation @WebServletinstead of adding them to your web.xml. Spring 3.2 already has @Configurationand @EnableXYZfor its context configuration. Does it have something similar for the DispatcherServlet, ie. is there a way to configure your full Spring application without any xml?

使用 servlet-api 3.0，您可以使用注释声明您的 servlet，@WebServlet而不是将它们添加到您的web.xml. Spring 3.2 已经有了@Configurationand @EnableXYZfor its context 配置。是否有类似的东西DispatcherServlet，即。有没有办法在没有任何 xml 的情况下配置完整的 Spring 应用程序？

回答by Alex

With JEE6, if your application container is Servlet 3.0 ready what you need to do is:

使用 JEE6，如果您的应用程序容器支持 Servlet 3.0，您需要做的是：

1. Create a custom class that implements ServletContainerInitializer(i.e. com.foo.FooServletContainer)
2. Create a file in your META-INF/servicesfolder named javax.servlet.ServletContainerInitializerwhich will contain the name of your implementation above (com.foo.FooServletContainer)

1. 创建一个实现ServletContainerInitializer的自定义类（即com.foo.FooServletContainer）
2. 在您的META-INF/services文件夹中创建一个名为的文件，该文件javax.servlet.ServletContainerInitializer将包含上述实现的名称 ( com.foo.FooServletContainer)

Spring 3 is bundled with a class named SpringServletContainerInitializerthat implements the stuff above (so you don't need to create yourself the file in META-INF/services. This class just calls an implementation of WebApplicationInitializer. So you just need to provide one class implementing it in your classpath (the following code is taken from the doc above).

春季3捆绑了一个名为类SpringServletContainerInitializer实现以上（这样你就不会需要自己创建的文件中的东西META-INF/services，这个类只是调用的实现WebApplicationInitializer。所以，你只需要提供一个类在类路径中实现它（以下代码取自上面的文档）。

public class FooInitializer implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) {
        WebApplicationContext appContext = ...;

        ServletRegistration.Dynamic dispatcher =
           container.addServlet("dispatcher", new DispatcherServlet(appContext));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/");
    }
 }

That's it for the web.xmlthing, but you need to configure the webapp using @Configuration, @EnableWebMvcetc..

这是它的web.xml事，但你需要使用配置Web应用程序@Configuration，@EnableWebMvc等等。

回答by Aniket Thakur

Yes you don't need web.xmlto startup your webapp Servlet 3.0+. As Alex already mentioned you can implement WebApplicationInitializerclass and override onStartup()method. WebApplicationInitializeris an interface provided by Spring MVC that ensures your implementation is detected and automatically used to initialize any Servlet 3 container.

是的，您不需要web.xml启动您的 webapp Servlet 3.0+。正如亚历克斯已经提到的，您可以实现WebApplicationInitializer类和覆盖onStartup()方法。WebApplicationInitializer是 Spring MVC 提供的接口，可确保检测到您的实现并自动用于初始化任何 Servlet 3 容器。

Is there a way to configure your full Spring application without any xml?

有没有办法在没有任何 xml 的情况下配置完整的 Spring 应用程序？

Adding this answer just to add another way. You don't need to implement WebApplicationInitializer. An abstract base class implementation of WebApplicationInitializernamed AbstractDispatcherServletInitializermakes it even easier to register the DispatcherServlet by simply overriding methods to specify the servlet mapping and the location of the DispatcherServlet configuration -

添加此答案只是为了添加另一种方式。您不需要实施WebApplicationInitializer. WebApplicationInitializernamed的抽象基类实现AbstractDispatcherServletInitializer使注册 DispatcherServlet 变得更加容易，只需覆盖方法来指定 servlet 映射和 DispatcherServlet 配置的位置 -

public class MyWebAppInitializer extends AbstractDispatcherServletInitializer {

    @Override
    protected WebApplicationContext createRootApplicationContext() {
        return null;
    }

    @Override
    protected WebApplicationContext createServletApplicationContext() {
        XmlWebApplicationContext cxt = new XmlWebApplicationContext();
        cxt.setConfigLocation("/WEB-INF/spring/dispatcher-config.xml");
        return cxt;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

}