org.springframework.web.filter

Class GenericFilterBean

java.lang.Object

org.springframework.web.filter.GenericFilterBean

All Implemented Interfaces:

Filter, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.DisposableBean, org.springframework.beans.factory.InitializingBean, org.springframework.context.EnvironmentAware, org.springframework.core.env.EnvironmentCapable, ServletContextAware

Direct Known Subclasses:

DelegatingFilterProxy, OncePerRequestFilter

public abstract class GenericFilterBean
extends Object
implements Filter, org.springframework.beans.factory.BeanNameAware, org.springframework.context.EnvironmentAware, org.springframework.core.env.EnvironmentCapable, ServletContextAware, org.springframework.beans.factory.InitializingBean, org.springframework.beans.factory.DisposableBean

Simple base implementation of Filter which treats its config parameters (init-param entries within the filter tag in web.xml) as bean properties.

A handy superclass for any type of filter. Type conversion of config parameters is automatic, with the corresponding setter method getting invoked with the converted value. It is also possible for subclasses to specify required properties. Parameters without matching bean property setter will simply be ignored.

This filter leaves actual filtering to subclasses, which have to implement the Filter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) method.

This generic filter base class has no dependency on the Spring ApplicationContext concept. Filters usually don't load their own context but rather access service beans from the Spring root application context, accessible via the filter's ServletContext (see WebApplicationContextUtils).

Since:

06.12.2003

Author:

Juergen Hoeller

See Also:

addRequiredProperty(java.lang.String), initFilterBean(), Filter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)

Field Summary

Fields

Modifier and Type	Field and Description
protected Log	logger Logger available to subclasses

Constructor Summary

Constructors

Constructor and Description
GenericFilterBean()

Method Summary

Modifier and Type	Method and Description
protected void	addRequiredProperty(String property) Subclasses can invoke this method to specify that this property (which must match a JavaBean property they expose) is mandatory, and must be supplied as a config parameter.
void	afterPropertiesSet() Calls the initFilterBean() method that might contain custom initialization of a subclass.
protected org.springframework.core.env.Environment	createEnvironment() Create and return a new StandardServletEnvironment.
void	destroy() Subclasses may override this to perform custom filter shutdown.
org.springframework.core.env.Environment	getEnvironment() Return the Environment associated with this filter.
FilterConfig	getFilterConfig() Make the FilterConfig of this filter available, if any.
protected String	getFilterName() Make the name of this filter available to subclasses.
protected ServletContext	getServletContext() Make the ServletContext of this filter available to subclasses.
void	init(FilterConfig filterConfig) Standard way of initializing this filter.
protected void	initBeanWrapper(org.springframework.beans.BeanWrapper bw) Initialize the BeanWrapper for this GenericFilterBean, possibly with custom editors.
protected void	initFilterBean() Subclasses may override this to perform custom initialization.
void	setBeanName(String beanName) Stores the bean name as defined in the Spring bean factory.
void	setEnvironment(org.springframework.core.env.Environment environment) Set the Environment that this filter runs in.
void	setServletContext(ServletContext servletContext) Stores the ServletContext that the bean factory runs in.

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.servlet.Filter

doFilter

Field Detail

logger

protected final Log logger

Logger available to subclasses

Constructor Detail

GenericFilterBean

public GenericFilterBean()

Method Detail

setBeanName

public void setBeanName(String beanName)

Stores the bean name as defined in the Spring bean factory.

Only relevant in case of initialization as bean, to have a name as fallback to the filter name usually provided by a FilterConfig instance.

Specified by:

setBeanName in interface org.springframework.beans.factory.BeanNameAware

See Also:

BeanNameAware, getFilterName()

setEnvironment

public void setEnvironment(org.springframework.core.env.Environment environment)

Set the Environment that this filter runs in.

Any environment set here overrides the StandardServletEnvironment provided by default.

This Environment object is used only for resolving placeholders in resource paths passed into init-parameters for this filter. If no init-params are used, this Environment can be essentially ignored.

Specified by:

setEnvironment in interface org.springframework.context.EnvironmentAware

getEnvironment

public org.springframework.core.env.Environment getEnvironment()

Return the Environment associated with this filter.

If none specified, a default environment will be initialized via createEnvironment().

Specified by:

getEnvironment in interface org.springframework.core.env.EnvironmentCapable

Since:

4.3.9

createEnvironment

protected org.springframework.core.env.Environment createEnvironment()

Create and return a new StandardServletEnvironment.

Subclasses may override this in order to configure the environment or specialize the environment type returned.

Since:

4.3.9

setServletContext

public void setServletContext(ServletContext servletContext)

Stores the ServletContext that the bean factory runs in.

Only relevant in case of initialization as bean, to have a ServletContext as fallback to the context usually provided by a FilterConfig instance.

Specified by:

setServletContext in interface ServletContextAware

Parameters:

servletContext - ServletContext object to be used by this object

See Also:

ServletContextAware, getServletContext()

afterPropertiesSet

public void afterPropertiesSet()
                        throws ServletException

Calls the initFilterBean() method that might contain custom initialization of a subclass.

Only relevant in case of initialization as bean, where the standard init(FilterConfig) method won't be called.

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

ServletException

See Also:

initFilterBean(), init(javax.servlet.FilterConfig)

destroy

public void destroy()

Subclasses may override this to perform custom filter shutdown.

Note: This method will be called from standard filter destruction as well as filter bean destruction in a Spring application context.

This default implementation is empty.

Specified by:

destroy in interface Filter

Specified by:

destroy in interface org.springframework.beans.factory.DisposableBean

addRequiredProperty

protected final void addRequiredProperty(String property)

Subclasses can invoke this method to specify that this property (which must match a JavaBean property they expose) is mandatory, and must be supplied as a config parameter. This should be called from the constructor of a subclass.

This method is only relevant in case of traditional initialization driven by a FilterConfig instance.

Parameters:

property - name of the required property

init

public final void init(FilterConfig filterConfig)
                throws ServletException

Standard way of initializing this filter. Map config parameters onto bean properties of this filter, and invoke subclass initialization.

Specified by:

init in interface Filter

Parameters:

filterConfig - the configuration for this filter

Throws:

ServletException - if bean properties are invalid (or required properties are missing), or if subclass initialization fails.

See Also:

initFilterBean()

initBeanWrapper

protected void initBeanWrapper(org.springframework.beans.BeanWrapper bw)
                        throws org.springframework.beans.BeansException

Initialize the BeanWrapper for this GenericFilterBean, possibly with custom editors.

This default implementation is empty.

Parameters:

bw - the BeanWrapper to initialize

Throws:

org.springframework.beans.BeansException - if thrown by BeanWrapper methods

See Also:

PropertyEditorRegistry.registerCustomEditor(java.lang.Class<?>, java.beans.PropertyEditor)

initFilterBean

protected void initFilterBean()
                       throws ServletException

Subclasses may override this to perform custom initialization. All bean properties of this filter will have been set before this method is invoked.

Note: This method will be called from standard filter initialization as well as filter bean initialization in a Spring application context. Filter name and ServletContext will be available in both cases.

This default implementation is empty.

Throws:

ServletException - if subclass initialization fails

See Also:

getFilterName(), getServletContext()

getFilterConfig

public final FilterConfig getFilterConfig()

Make the FilterConfig of this filter available, if any. Analogous to GenericServlet's getServletConfig().

Public to resemble the getFilterConfig() method of the Servlet Filter version that shipped with WebLogic 6.1.

Returns:

the FilterConfig instance, or null if none available

See Also:

GenericServlet.getServletConfig()

getFilterName

protected final String getFilterName()

Make the name of this filter available to subclasses. Analogous to GenericServlet's getServletName().

Takes the FilterConfig's filter name by default. If initialized as bean in a Spring application context, it falls back to the bean name as defined in the bean factory.

Returns:

the filter name, or null if none available

See Also:

GenericServlet.getServletName(), FilterConfig.getFilterName(), setBeanName(java.lang.String)

getServletContext

protected final ServletContext getServletContext()

Make the ServletContext of this filter available to subclasses. Analogous to GenericServlet's getServletContext().

Takes the FilterConfig's ServletContext by default. If initialized as bean in a Spring application context, it falls back to the ServletContext that the bean factory runs in.

Returns:

the ServletContext instance, or null if none available

See Also:

GenericServlet.getServletContext(), FilterConfig.getServletContext(), setServletContext(javax.servlet.ServletContext)