Package javax.servlet

Class GenericFilter

java.lang.Object
javax.servlet.GenericFilter
All Implemented Interfaces:
Serializable, Filter, FilterConfig
Direct Known Subclasses:
HttpFilter
public abstract class GenericFilter extends Object implements Filter, FilterConfig, Serializable
Provides a base class that implements the Filter and FilterConfig interfaces to reduce boilerplate when writing new filters.
Since:
Servlet 4.0
See Also:

  • Constructor Details

    • GenericFilter

      public GenericFilter()

  • Method Details

    • getInitParameter

      public String getInitParameter(String name)
      Description copied from interface: FilterConfig
      Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist.
      Specified by:
      getInitParameter in interface FilterConfig
      Parameters:
      name - String specifying the name of the initialization parameter
      Returns:
      String containing the value of the initialization parameter

    • getInitParameterNames

      public Enumeration<String> getInitParameterNames()
      Description copied from interface: FilterConfig
      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.
      Specified by:
      getInitParameterNames in interface FilterConfig
      Returns:
      Enumeration of String objects containing the names of the filter's initialization parameters

    • getFilterConfig

      public FilterConfig getFilterConfig()
      Obtain the FilterConfig used to initialise this Filter instance.
      Returns:
      The config previously passed to the init(FilterConfig) method

    • getServletContext

      public ServletContext getServletContext()
      Description copied from interface: FilterConfig
      Returns a reference to the ServletContext in which the caller is executing.
      Specified by:
      getServletContext in interface FilterConfig
      Returns:
      ServletContext object, used by the caller to interact with its servlet container
      See Also:

    • init

      public void init(FilterConfig filterConfig) throws ServletException
      Description copied from interface: Filter
      Called by the web container to indicate to a filter that it is being placed into service. The servlet container calls the init method exactly once after instantiating the filter. The init method must complete successfully before the filter is asked to do any filtering work.

      The web container cannot place the filter into service if the init method either:

      • Throws a ServletException
      • Does not return within a time period defined by the web container
      The default implementation is a NO-OP.
      Specified by:
      init in interface Filter
      Parameters:
      filterConfig - The configuration information associated with the filter instance being initialised
      Throws:
      ServletException - if the initialisation fails

    • init

      public void init() throws ServletException
      Convenience method for sub-classes to save them having to call super.init(config). This is a NO-OP by default.
      Throws:
      ServletException - If an exception occurs that interrupts the Filter's normal operation

    • getFilterName

      public String getFilterName()
      Description copied from interface: FilterConfig
      Get the name of the filter.
      Specified by:
      getFilterName in interface FilterConfig
      Returns:
      The filter-name of this filter as defined in the deployment descriptor.