org.springframework.web.servlet
Class FrameworkServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.springframework.web.servlet.HttpServletBean
              org.springframework.web.servlet.FrameworkServlet

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

DispatcherServlet

public abstract class FrameworkServlet

extends HttpServletBean

Base servlet for servlets within the web framework. Allows integration with an application context, in a JavaBean-based overall solution.

This class offers the following functionality:

• Uses a WebApplicationContext to access a BeanFactory. The servlet's configuration is determined by beans in the servlet's namespace.
• Publishes events on request processing, whether or not a request is successfully handled.

Subclasses must implement doService() to handle requests. Because this extends HttpServletBean rather than HttpServlet directly, bean properties are mapped onto it. Subclasses can override initFrameworkServlet() for custom initialization.

Regards a "contextClass" parameter at the servlet init-param level, falling back to the default context class (XmlWebApplicationContext) if not found. With the default FrameworkServlet, a context class needs to implement ConfigurableWebApplicationContext.

Passes a "contextConfigLocation" servlet init-param to the context instance, parsing it into potentially multiple file paths which can be separated by any number of commas and spaces, like "test-servlet.xml, myServlet.xml". If not explicitly specified, the context implementation is supposed to build a default location from the namespace of the servlet.

Note: In case of multiple config locations, later bean definitions will override ones defined in earlier loaded files, at least when using one of Spring's default ApplicationContext implementations. This can be leveraged to deliberately override certain bean definitions via an extra XML file.

The default namespace is "'servlet-name'-servlet", e.g. "test-servlet" for a servlet-name "test" (leading to a "/WEB-INF/test-servlet.xml" default location with XmlWebApplicationContext). The namespace can also be set explicitly via the "namespace" servlet init-param.

Version:

$Revision: 1.14 $

Author:

Rod Johnson

See Also:

doService(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), initFrameworkServlet(), setContextClass(java.lang.Class), setContextConfigLocation(java.lang.String), setNamespace(java.lang.String), Serialized Form

Field Summary

static java.lang.Class	DEFAULT_CONTEXT_CLASS Default context class for FrameworkServlet.
static java.lang.String	DEFAULT_NAMESPACE_SUFFIX Suffix for namespace bean factory names.
static java.lang.String	SERVLET_CONTEXT_PREFIX Prefix for the ServletContext attribute for the web application context.

Fields inherited from class org.springframework.web.servlet.HttpServletBean

logger

Constructor Summary

FrameworkServlet()

Method Summary

protected WebApplicationContext	createWebApplicationContext(WebApplicationContext parent) Instantiate the WebApplicationContext for this servlet, either a default XmlWebApplicationContext or a custom context class if set.
void	destroy()
protected void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) It's up to each subclass to decide whether or not it supports a request method.
protected void	doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) It's up to each subclass to decide whether or not it supports a request method.
protected abstract void	doService(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Subclasses must implement this method to do the work of request handling.
java.lang.Class	getContextClass() Return the custom context class.
java.lang.String	getContextConfigLocation() Return the explicit context config location, if any.
java.lang.String	getNamespace() Return the namespace for this servlet, falling back to default scheme if no custom namespace was set: e.g.
java.lang.String	getServletContextAttributeName() Return the ServletContext attribute name for this servlet's WebApplicationContext.
WebApplicationContext	getWebApplicationContext() Return this servlet's WebApplicationContext.
protected void	initFrameworkServlet() This method will be invoked after any bean properties have been set and the WebApplicationContext has been loaded.
protected void	initServletBean() Overridden method of HttpServletBean, invoked after any bean properties have been set.
protected WebApplicationContext	initWebApplicationContext() Initialize and publish the WebApplicationContext for this servlet.
boolean	isPublishContext() Return whether to publish this servlet's context as a ServletContext attribute.
void	setContextClass(java.lang.Class contextClass) Set a custom context class.
void	setContextConfigLocation(java.lang.String contextConfigLocation) Set the context config location explicitly, instead of relying on the default location built from the namespace.
void	setNamespace(java.lang.String namespace) Set a custom namespace for this servlet, to be used for building a default context config location.
void	setPublishContext(boolean publishContext) Set whether to publish this servlet's context as a ServletContext attribute.

Methods inherited from class org.springframework.web.servlet.HttpServletBean

init, setRequiredProperty

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_NAMESPACE_SUFFIX

public static final java.lang.String DEFAULT_NAMESPACE_SUFFIX

Suffix for namespace bean factory names. If a servlet of this class is given the name 'test' in a context, the namespace used by the servlet will resolve to 'test-servlet'.

See Also:

Constant Field Values

DEFAULT_CONTEXT_CLASS

public static final java.lang.Class DEFAULT_CONTEXT_CLASS

Default context class for FrameworkServlet.

See Also:

XmlWebApplicationContext

SERVLET_CONTEXT_PREFIX

public static final java.lang.String SERVLET_CONTEXT_PREFIX

Prefix for the ServletContext attribute for the web application context. The completion is the servlet name.

Constructor Detail

FrameworkServlet

public FrameworkServlet()

Method Detail

setContextClass

public final void setContextClass(java.lang.Class contextClass)

Set a custom context class. This class must be of type WebApplicationContext, with the default FrameworkServlet implementing ConfigurableWebApplicationContext.

See Also:

createWebApplicationContext(org.springframework.web.context.WebApplicationContext)

getContextClass

public java.lang.Class getContextClass()

Return the custom context class.

setNamespace

public void setNamespace(java.lang.String namespace)

Set a custom namespace for this servlet, to be used for building a default context config location.

getNamespace

public java.lang.String getNamespace()

Return the namespace for this servlet, falling back to default scheme if no custom namespace was set: e.g. "test-servlet" for a servlet named "test".

setContextConfigLocation

public void setContextConfigLocation(java.lang.String contextConfigLocation)

Set the context config location explicitly, instead of relying on the default location built from the namespace. This location string can consist of multiple locations separated by any number of commas and spaces.

getContextConfigLocation

public java.lang.String getContextConfigLocation()

Return the explicit context config location, if any.

setPublishContext

public final void setPublishContext(boolean publishContext)

Set whether to publish this servlet's context as a ServletContext attribute. Default is true.

Parameters:

publishContext - whether we should publish this servlet's WebApplicationContext as a ServletContext attribute, available to all objects in this web container. Default is true. This is especially handy during testing, although it is debatable whether it's good practice to let other application objects access the context this way.

isPublishContext

public boolean isPublishContext()

Return whether to publish this servlet's context as a ServletContext attribute.

getWebApplicationContext

public final WebApplicationContext getWebApplicationContext()

Return this servlet's WebApplicationContext.

getServletContextAttributeName

public final java.lang.String getServletContextAttributeName()

Return the ServletContext attribute name for this servlet's WebApplicationContext.

initServletBean

protected final void initServletBean()
                              throws javax.servlet.ServletException,
                                     BeansException

Overridden method of HttpServletBean, invoked after any bean properties have been set. Creates this servlet's WebApplicationContext.

Overrides:

initServletBean in class HttpServletBean

Throws:

javax.servlet.ServletException - if subclass initialization fails

BeansException

initWebApplicationContext

protected WebApplicationContext initWebApplicationContext()
                                                   throws BeansException

Initialize and publish the WebApplicationContext for this servlet. Delegates to createWebApplicationContext for actual creation. Can be overridden in subclasses.

Throws:

BeansException - if the context couldn't be initialized

See Also:

createWebApplicationContext(org.springframework.web.context.WebApplicationContext)

createWebApplicationContext

protected WebApplicationContext createWebApplicationContext(WebApplicationContext parent)
                                                     throws BeansException

Instantiate the WebApplicationContext for this servlet, either a default XmlWebApplicationContext or a custom context class if set. This implementation expects custom contexts to implement ConfigurableWebApplicationContext. Can be overridden in subclasses.

Throws:

BeansException - if the context couldn't be initialized

See Also:

setContextClass(java.lang.Class), XmlWebApplicationContext

destroy

public void destroy()

doGet

protected final void doGet(javax.servlet.http.HttpServletRequest request,
                           javax.servlet.http.HttpServletResponse response)
                    throws javax.servlet.ServletException,
                           java.io.IOException

It's up to each subclass to decide whether or not it supports a request method. It should throw a Servlet exception if it doesn't support a particular request type. This might commonly be done with GET for forms, for example

Throws:

javax.servlet.ServletException

java.io.IOException

doPost

protected final void doPost(javax.servlet.http.HttpServletRequest request,
                            javax.servlet.http.HttpServletResponse response)
                     throws javax.servlet.ServletException,
                            java.io.IOException

It's up to each subclass to decide whether or not it supports a request method. It should throw a Servlet exception if it doesn't support a particular request type. This might commonly be done with GET for forms, for example

Throws:

javax.servlet.ServletException

java.io.IOException

initFrameworkServlet

protected void initFrameworkServlet()
                             throws javax.servlet.ServletException,
                                    BeansException

This method will be invoked after any bean properties have been set and the WebApplicationContext has been loaded. The default implementation is empty; subclasses may override this method to perform any initialization they require.

Throws:

javax.servlet.ServletException - in case of an initialization exception

BeansException - if thrown by ApplicationContext methods

doService

protected abstract void doService(javax.servlet.http.HttpServletRequest request,
                                  javax.servlet.http.HttpServletResponse response)
                           throws java.lang.Exception

Subclasses must implement this method to do the work of request handling. The contract is the same as that for the doGet or doPost methods of HttpServlet. This class intercepts calls to ensure that event publication takes place.

Throws:

java.lang.Exception - in case of any kind of processing failure

See Also:

HttpServlet.doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), HttpServlet.doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)