Package jakarta.servlet

Class GenericFilter

  • All Implemented Interfaces:
    Filter, FilterConfig, java.io.Serializable
    Direct Known Subclasses:
    HttpFilter
    public abstract class GenericFilter
extends java.lang.Object
implements Filter, FilterConfig, java.io.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:
    Filter, FilterConfig, Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      GenericFilter()  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      FilterConfig getFilterConfig()
      Obtain the FilterConfig used to initialise this Filter instance.
      java.lang.String getFilterName()
      Get the name of the filter.
      java.lang.String getInitParameter​(java.lang.String name)
      Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist.
      java.util.Enumeration<java.lang.String> 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.
      ServletContext getServletContext()
      Returns a reference to the ServletContext in which the caller is executing.
      void init()
      Convenience method for sub-classes to save them having to call super.init(config).
      void init​(FilterConfig filterConfig)
      Called by the web container to indicate to a filter that it is being placed into service.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • GenericFilter

        public GenericFilter()

    • Method Detail

      • getInitParameter

        public java.lang.String getInitParameter​(java.lang.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 java.util.Enumeration<java.lang.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

      • 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 java.lang.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.