接口 Controller
- 所有已知实现类:
AbstractController
,AbstractUrlViewController
,MultiActionController
,ParameterizableViewController
,ServletForwardingController
,ServletWrappingController
,UrlFilenameViewController
public interface Controller
Base Controller interface, representing a component that receivesHttpServletRequest
andHttpServletResponse
instances just like aHttpServlet
but is able to participate in an MVC workflow. Controllers are comparable to the notion of a StrutsAction
.Any implementation of the Controller interface should be a reusable, thread-safe class, capable of handling multiple HTTP requests throughout the lifecycle of an application. To be able to configure a Controller easily, Controller implementations are encouraged to be (and usually are) JavaBeans.
Workflow
After a
DispatcherServlet
has received a request and has done its work to resolve locales, themes, and suchlike, it then tries to resolve a Controller, using aHandlerMapping
. When a Controller has been found to handle the request, thehandleRequest
method of the located Controller will be invoked; the located Controller is then responsible for handling the actual request and — if applicable — returning an appropriateModelAndView
. So actually, this method is the main entry point for theDispatcherServlet
which delegates requests to controllers.So basically any direct implementation of the
Controller
interface just handles HttpServletRequests and should return a ModelAndView, to be further interpreted by the DispatcherServlet. Any additional functionality such as optional validation, form handling, etc. should be obtained through extendingAbstractController
or one of its subclasses.Notes on design and testing
The Controller interface is explicitly designed to operate on HttpServletRequest and HttpServletResponse objects, just like an HttpServlet. It does not aim to decouple itself from the Servlet API, in contrast to, for example, WebWork, JSF or Tapestry. Instead, the full power of the Servlet API is available, allowing Controllers to be general-purpose: a Controller is able to not only handle web user interface requests but also to process remoting protocols or to generate reports on demand.
Controllers can easily be tested by passing in mock objects for the HttpServletRequest and HttpServletResponse objects as parameters to the
handleRequest
method. As a convenience, Spring ships with a set of Servlet API mocks that are suitable for testing any kind of web components, but are particularly suitable for testing Spring web controllers. In contrast to a Struts Action, there is no need to mock the ActionServlet or any other infrastructure; mocking HttpServletRequest and HttpServletResponse is sufficient.If Controllers need to be aware of specific environment references, they can choose to implement specific awareness interfaces, just like any other bean in a Spring (web) application context can do, for example:
org.springframework.context.ApplicationContextAware
org.springframework.context.ResourceLoaderAware
org.springframework.web.context.ServletContextAware
Such environment references can easily be passed in testing environments, through the corresponding setters defined in the respective awareness interfaces. In general, it is recommended to keep the dependencies as minimal as possible: for example, if all you need is resource loading, implement ResourceLoaderAware only. Alternatively, derive from the WebApplicationObjectSupport base class, which gives you all those references through convenient accessors but requires an ApplicationContext reference on initialization.
Controllers can optionally implement the
LastModified
interface.- 作者:
- Rod Johnson, Juergen Hoeller
- 另请参阅:
LastModified
,SimpleControllerHandlerAdapter
,AbstractController
,MockHttpServletRequest
,MockHttpServletResponse
,ApplicationContextAware
,ResourceLoaderAware
,ServletContextAware
,WebApplicationObjectSupport
方法概要
所有方法 实例方法 抽象方法 修饰符和类型 方法 说明 ModelAndView
handleRequest(HttpServletRequest request, HttpServletResponse response)
Process the request and return a ModelAndView object which the DispatcherServlet will render.
方法详细资料
handleRequest
ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception
Process the request and return a ModelAndView object which the DispatcherServlet will render. Anull
return value is not an error: it indicates that this object completed request processing itself and that there is therefore no ModelAndView to render.- 参数:
request
- current HTTP requestresponse
- current HTTP response- 返回:
- a ModelAndView to render, or
null
if handled directly - 抛出:
Exception
- in case of errors