spring与servlet3.0无web.xml文件时的配置方式

摘要: spring webmvc servlet 3.0 web.xml ; spring在使用servlet3.0时的配置方式

这里只做简要的记录，更详细的使用方式，更详细的资料参见spring参考文档（21.15 Code-based Servlet container initialization），以后会慢慢补充。



21.15 Code-based Servlet container initialization

In a Servlet 3.0+ environment, you have the option of configuring the Servlet container programmatically as an alternative or in combination with a

web.xml

file. Below is an example of registering a

DispatcherServlet

:

import org.springframework.web.WebApplicationInitializer; public class MyWebApplicationInitializer implements WebApplicationInitializer {         @Override    public void onStartup(ServletContext container) {        XmlWebApplicationContext appContext = new XmlWebApplicationContext();        appContext.setConfigLocation("/WEB-INF/spring/dispatcher-config.xml");        ServletRegistration.Dynamic registration = container.addServlet("dispatcher", new DispatcherServlet(appContext));        registration.setLoadOnStartup(1);        registration.addMapping("/");    } }

WebApplicationInitializer

is an interface provided by Spring MVC that ensures your implementation is detected and automatically used to initialize any Servlet 3 container. An abstract base class implementation of

WebApplicationInitializer

named

AbstractDispatcherServletInitializer

makes it even easier to register the

DispatcherServlet

by simply overriding methods to specify the servlet mapping and the location of the

DispatcherServlet

configuration:

public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {         @Override    protected Class<?>[] getRootConfigClasses() {        return null;    }    @Override    protected Class<?>[] getServletConfigClasses() {        return new Class[] { MyWebConfig.class };    }    @Override    protected String[] getServletMappings() {        return new String[] { "/" };    } }

The above example is for an application that uses Java-based Spring configuration. If using XML-based Spring configuration, extend directly from

AbstractDispatcherServletInitializer

:

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[] { "/" };    } }

AbstractDispatcherServletInitializer

also provides a convenient way to add

Filter

instances and have them automatically mapped to the

DispatcherServlet

:

public class MyWebAppInitializer extends AbstractDispatcherServletInitializer {    // ...    @Override    protected Filter[] getServletFilters() {        return new Filter[] { new HiddenHttpMethodFilter(), new CharacterEncodingFilter() };    } }

Each filter is added with a default name based on its concrete type and automatically mapped to the

DispatcherServlet

.

The

isAsyncSupported

protected method of

AbstractDispatcherServletInitializer

provides a single place to enable async support on the

DispatcherServlet

and all filters mapped to it. By default this flag is set to

true

.

Finally, if you need to further customize the

DispatcherServlet

itself, you can override the

createDispatcherServlet

method.