JavaEE API 8.0.1 · javax.servlet.GenericFilter

Defines a generic, protocol-independent filter. To write an HTTP filter for use on the Web, extend javax.servlet.http.HttpFilter instead.

GenericFilter implements the Filter and FilterConfig interfaces. GenericFilter may be directly extended by a filter, although it's more common to extend a protocol-specific subclass such as HttpFilter.

GenericFilter makes writing filters easier. It provides simple versions of the lifecycle methods init and destroy and of the methods in the FilterConfig interface.

To write a generic filter, you need only override the abstract doFilter method.

Modifier and Type	Field and Description
private transient FilterConfig	config
private static final String	LSTRING_FILE
private static final ResourceBundle	lStrings

Constructor Summary

Access	Constructor and Description
public	GenericFilter() Does nothing.

Method Summary

Modifier and Type	Method and Description
public FilterConfig	Returns: FilterConfig the `FilterConfig` object that initialized this filter getFilterConfig() Returns this servlet's `ServletConfig` object.
public String	Returns: the name of this filter instance getFilterName() Implements javax.servlet.FilterConfig.getFilterName. Returns the name of this filter instance.
public String	Returns: String a `String` containing the value of the initialization parameter getInitParameter(String a `String` specifying the name of the initialization parameter name) Implements javax.servlet.FilterConfig.getInitParameter. Returns a `String` containing the value of the named initialization parameter, or `null` if the parameter does not exist.
public Enumeration<String>	Returns: Enumeration an enumeration of `String` objects containing the names of the filter's initialization parameters getInitParameterNames() Implements javax.servlet.FilterConfig.getInitParameterNames. Returns the names of the filter's initialization parameters as an `Enumeration` of `String` objects, or an empty `Enumeration` if the filter has no initialization parameters.
public ServletContext	Returns: ServletContext the `ServletContext` object passed to this filter by the `init` method getServletContext() Implements javax.servlet.FilterConfig.getServletContext. Returns a reference to the `ServletContext` in which this filter is running.
public void	init(FilterConfig the `FilterConfig` object that contains configuration information for this filter config) Overrides default javax.servlet.Filter.init. Called by the servlet container to indicate to a filter that it is being placed into service.
public void	init() A convenience method which can be overridden so that there's no need to call `super.init(config)`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

config	back to summary
private transient FilterConfig config

LSTRING_FILE	back to summary
private static final String LSTRING_FILE

lStrings	back to summary
private static final ResourceBundle lStrings

Constructor Detail

GenericFilter back to summary

GenericFilter	back to summary
public GenericFilter() Does nothing. All of the filter initialization is done by one of the `init` methods. Since Servlet 4.0

public GenericFilter()

Does nothing. All of the filter initialization is done by one of the init methods.

Since: Servlet 4.0

Method Detail

getFilterConfig back to summary

getFilterConfig	back to summary
public FilterConfig getFilterConfig() Returns this servlet's `ServletConfig` object. Returns:FilterConfig FilterConfig the `FilterConfig` object that initialized this filter Since Servlet 4.0

public FilterConfig getFilterConfig()

Returns this servlet's ServletConfig object.

Returns:FilterConfig: FilterConfig the FilterConfig object that initialized this filter
Since: Servlet 4.0

getFilterName back to summary

getFilterName	back to summary
public String getFilterName() Implements javax.servlet.FilterConfig.getFilterName. Returns the name of this filter instance. See `FilterConfig#getFilterName`. Returns:String the name of this filter instance Annotations @Override Since Servlet 4.0

public String getFilterName()

Implements javax.servlet.FilterConfig.getFilterName.

Returns the name of this filter instance. See FilterConfig#getFilterName.

Returns:String

the name of this filter instance

Annotations

@Override

Since

Servlet 4.0

getInitParameter back to summary

getInitParameter	back to summary
public String getInitParameter(String name) Implements javax.servlet.FilterConfig.getInitParameter. Returns a `String` containing the value of the named initialization parameter, or `null` if the parameter does not exist. See `FilterConfig#getInitParameter`. This method is supplied for convenience. It gets the value of the named parameter from the servlet's `ServletConfig` object. Parameters name:String a `String` specifying the name of the initialization parameter Returns:String String a `String` containing the value of the initialization parameter Annotations @Override Since Servlet 4.0

public String getInitParameter(String name)

Implements javax.servlet.FilterConfig.getInitParameter.

Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist. See FilterConfig#getInitParameter.

This method is supplied for convenience. It gets the value of the named parameter from the servlet's ServletConfig object.

Parameters

name:String: a String specifying the name of the initialization parameter

Returns:String

String a String containing the value of the initialization parameter

Annotations

@Override

Since

Servlet 4.0

getInitParameterNames back to summary

getInitParameterNames	back to summary
public Enumeration<String> getInitParameterNames() Implements javax.servlet.FilterConfig.getInitParameterNames. Returns the names of the filter's initialization parameters as an `Enumeration` of `String` objects, or an empty `Enumeration` if the filter has no initialization parameters. See `FilterConfig#getInitParameterNames`. This method is supplied for convenience. It gets the parameter names from the filter's `FilterConfig` object. Returns:Enumeration<String> Enumeration an enumeration of `String` objects containing the names of the filter's initialization parameters Annotations @Override Since Servlet 4.0

public Enumeration<String> getInitParameterNames()

Implements javax.servlet.FilterConfig.getInitParameterNames.

Returns the names of the filter's initialization parameters as an Enumeration of String objects, or an empty Enumeration if the filter has no initialization parameters. See FilterConfig#getInitParameterNames.

This method is supplied for convenience. It gets the parameter names from the filter's FilterConfig object.

Returns:Enumeration<String>

Enumeration an enumeration of String objects containing the names of the filter's initialization parameters

Annotations

@Override

Since

Servlet 4.0

getServletContext back to summary

getServletContext	back to summary
public ServletContext getServletContext() Implements javax.servlet.FilterConfig.getServletContext. Returns a reference to the `ServletContext` in which this filter is running. See `FilterConfig#getServletContext`. This method is supplied for convenience. It gets the context from the filter's `FilterConfig` object. Returns:ServletContext ServletContext the `ServletContext` object passed to this filter by the `init` method Annotations @Override Since Servlet 4.0

public ServletContext getServletContext()

Implements javax.servlet.FilterConfig.getServletContext.

Returns a reference to the ServletContext in which this filter is running. See FilterConfig#getServletContext.

This method is supplied for convenience. It gets the context from the filter's FilterConfig object.

Returns:ServletContext

ServletContext the ServletContext object passed to this filter by the init method

Annotations

@Override

Since

Servlet 4.0

init back to summary

init	back to summary
public void init(FilterConfig config) throws ServletException Overrides default javax.servlet.Filter.init. Called by the servlet container to indicate to a filter that it is being placed into service. See `Filter#init`. This implementation stores the `FilterConfig` object it receives from the servlet container for later use. When overriding this form of the method, call `super.init(config)`. Parameters config:FilterConfig the `FilterConfig` object that contains configuration information for this filter Annotations @Override Exceptions ServletException: if an exception occurs that interrupts the servlet's normal operation Since Servlet 4.0 See Also `UnavailableException`

public void init(FilterConfig config) throws ServletException

Overrides default javax.servlet.Filter.init.

Called by the servlet container to indicate to a filter that it is being placed into service. See Filter#init.

This implementation stores the FilterConfig object it receives from the servlet container for later use. When overriding this form of the method, call super.init(config).

Parameters

config:FilterConfig: the FilterConfig object that contains configuration information for this filter

Annotations

@Override

Exceptions

ServletException:: if an exception occurs that interrupts the servlet's normal operation

Since

Servlet 4.0

See Also

UnavailableException

init back to summary

init	back to summary
public void init() throws ServletException A convenience method which can be overridden so that there's no need to call `super.init(config)`. Instead of overriding `init(FilterConfig)`, simply override this method and it will be called by `GenericFilter.init(FilterConfig config)`. The `FilterConfig` object can still be retrieved via `getFilterConfig`. Exceptions ServletException: if an exception occurs that interrupts the servlet's normal operation Since Servlet 4.0

public void init() throws ServletException

A convenience method which can be overridden so that there's no need to call super.init(config).

Instead of overriding init(FilterConfig), simply override this method and it will be called by GenericFilter.init(FilterConfig config). The FilterConfig object can still be retrieved via getFilterConfig.

Exceptions

ServletException:: if an exception occurs that interrupts the servlet's normal operation

Since

Servlet 4.0

public abstract Class GenericFilter

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail