Package javax.servlet
Class GenericFilter
- java.lang.Object
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- javax.servlet.GenericFilter
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- All Implemented Interfaces:
java.io.Serializable,Filter,FilterConfig
- 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
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Constructor Summary
Constructors Constructor Description GenericFilter()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description FilterConfiggetFilterConfig()Obtain the FilterConfig used to initialise this Filter instance.java.lang.StringgetFilterName()Get the name of the filter.java.lang.StringgetInitParameter(java.lang.String name)Returns aStringcontaining the value of the named initialization parameter, ornullif the parameter does not exist.java.util.Enumeration<java.lang.String>getInitParameterNames()Returns the names of the filter's initialization parameters as anEnumerationofStringobjects, or an emptyEnumerationif the filter has no initialization parameters.ServletContextgetServletContext()Returns a reference to theServletContextin which the caller is executing.voidinit()Convenience method for sub-classes to save them having to callsuper.init(config).voidinit(FilterConfig filterConfig)Called by the web container to indicate to a filter that it is being placed into service.
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Method Detail
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getInitParameter
public java.lang.String getInitParameter(java.lang.String name)
Description copied from interface:FilterConfigReturns aStringcontaining the value of the named initialization parameter, ornullif the parameter does not exist.- Specified by:
getInitParameterin interfaceFilterConfig- Parameters:
name-Stringspecifying the name of the initialization parameter- Returns:
Stringcontaining the value of the initialization parameter
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getInitParameterNames
public java.util.Enumeration<java.lang.String> getInitParameterNames()
Description copied from interface:FilterConfigReturns the names of the filter's initialization parameters as anEnumerationofStringobjects, or an emptyEnumerationif the filter has no initialization parameters.- Specified by:
getInitParameterNamesin interfaceFilterConfig- Returns:
EnumerationofStringobjects containing the names of the filter's initialization parameters
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getFilterConfig
public FilterConfig getFilterConfig()
Obtain the FilterConfig used to initialise this Filter instance.- Returns:
- The config previously passed to the
init(FilterConfig)method
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getServletContext
public ServletContext getServletContext()
Description copied from interface:FilterConfigReturns a reference to theServletContextin which the caller is executing.- Specified by:
getServletContextin interfaceFilterConfig- Returns:
ServletContextobject, used by the caller to interact with its servlet container- See Also:
ServletContext
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init
public void init(FilterConfig filterConfig) throws ServletException
Description copied from interface:FilterCalled 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
- Specified by:
initin interfaceFilter- Parameters:
filterConfig- The configuration information associated with the filter instance being initialised- Throws:
ServletException- if the initialisation fails
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init
public void init() throws ServletExceptionConvenience method for sub-classes to save them having to callsuper.init(config). This is a NO-OP by default.- Throws:
ServletException- If an exception occurs that interrupts the Filter's normal operation
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getFilterName
public java.lang.String getFilterName()
Description copied from interface:FilterConfigGet the name of the filter.- Specified by:
getFilterNamein interfaceFilterConfig- Returns:
- The filter-name of this filter as defined in the deployment descriptor.
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