https://tomcat.apache.org/: Tomcat Servlet Engine Core Classes and Standard implementations 
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 * contributor license agreements.  See the NOTICE file distributed with
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 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 * Unless required by applicable law or agreed to in writing, software
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package org.apache.catalina;


import jakarta.servlet.MultipartConfigElement;
import jakarta.servlet.Servlet;
import jakarta.servlet.ServletException;
import jakarta.servlet.UnavailableException;



A Wrapper is a Container that represents an individual servlet
definition from the deployment descriptor of the web application.  It
provides a convenient mechanism to use Interceptors that see every single
request to the servlet represented by this definition.


Implementations of Wrapper are responsible for managing the servlet life
cycle for their underlying servlet class, including calling init() and
destroy() at appropriate times, as well as respecting the existence of
the SingleThreadModel declaration on the servlet class itself.


The parent Container attached to a Wrapper will generally be an
implementation of Context, representing the servlet context (and
therefore the web application) within which this servlet executes.


Child Containers are not allowed on Wrapper implementations, so the
addChild() method should throw an
IllegalArgumentException.

Author:Craig R. McClanahan
/**
 * A <b>Wrapper</b> is a Container that represents an individual servlet
 * definition from the deployment descriptor of the web application.  It
 * provides a convenient mechanism to use Interceptors that see every single
 * request to the servlet represented by this definition.
 * <p>
 * Implementations of Wrapper are responsible for managing the servlet life
 * cycle for their underlying servlet class, including calling init() and
 * destroy() at appropriate times, as well as respecting the existence of
 * the SingleThreadModel declaration on the servlet class itself.
 * <p>
 * The parent Container attached to a Wrapper will generally be an
 * implementation of Context, representing the servlet context (and
 * therefore the web application) within which this servlet executes.
 * <p>
 * Child Containers are not allowed on Wrapper implementations, so the
 * <code>addChild()</code> method should throw an
 * <code>IllegalArgumentException</code>.
 *
 * @author Craig R. McClanahan
 */
public interface Wrapper extends Container {

    
Container event for adding a wrapper.

/**
     * Container event for adding a wrapper.
     */
    public static final String ADD_MAPPING_EVENT = "addMapping";

    
Container event for removing a wrapper.

/**
     * Container event for removing a wrapper.
     */
    public static final String REMOVE_MAPPING_EVENT = "removeMapping";

    // ------------------------------------------------------------- Properties


    
Returns:the available date/time for this servlet, in milliseconds since
the epoch.  If this date/time is in the future, any request for this
servlet will return an SC_SERVICE_UNAVAILABLE error.  If it is zero,
the servlet is currently available.  A value equal to Long.MAX_VALUE
is considered to mean that unavailability is permanent.
/**
     * @return the available date/time for this servlet, in milliseconds since
     * the epoch.  If this date/time is in the future, any request for this
     * servlet will return an SC_SERVICE_UNAVAILABLE error.  If it is zero,
     * the servlet is currently available.  A value equal to Long.MAX_VALUE
     * is considered to mean that unavailability is permanent.
     */
    public long getAvailable();


    
Set the available date/time for this servlet, in milliseconds since the
epoch.  If this date/time is in the future, any request for this servlet
will return an SC_SERVICE_UNAVAILABLE error.  A value equal to
Long.MAX_VALUE is considered to mean that unavailability is permanent.

Params:
  • available – The new available date/time
/**
     * Set the available date/time for this servlet, in milliseconds since the
     * epoch.  If this date/time is in the future, any request for this servlet
     * will return an SC_SERVICE_UNAVAILABLE error.  A value equal to
     * Long.MAX_VALUE is considered to mean that unavailability is permanent.
     *
     * @param available The new available date/time
     */
    public void setAvailable(long available);


    
Returns:the load-on-startup order value (negative value means
load on first call).
/**
     * @return the load-on-startup order value (negative value means
     * load on first call).
     */
    public int getLoadOnStartup();


    
Set the load-on-startup order value (negative value means
load on first call).

Params:
  • value – New load-on-startup value
/**
     * Set the load-on-startup order value (negative value means
     * load on first call).
     *
     * @param value New load-on-startup value
     */
    public void setLoadOnStartup(int value);


    
Returns:the run-as identity for this servlet.
/**
     * @return the run-as identity for this servlet.
     */
    public String getRunAs();


    
Set the run-as identity for this servlet.

Params:
  • runAs – New run-as identity value
/**
     * Set the run-as identity for this servlet.
     *
     * @param runAs New run-as identity value
     */
    public void setRunAs(String runAs);


    
Returns:the fully qualified servlet class name for this servlet.
/**
     * @return the fully qualified servlet class name for this servlet.
     */
    public String getServletClass();


    
Set the fully qualified servlet class name for this servlet.

Params:
  • servletClass – Servlet class name
/**
     * Set the fully qualified servlet class name for this servlet.
     *
     * @param servletClass Servlet class name
     */
    public void setServletClass(String servletClass);


    
Gets the names of the methods supported by the underlying servlet.
This is the same set of methods included in the Allow response header
in response to an OPTIONS request method processed by the underlying
servlet.

Throws:
Returns:Array of names of the methods supported by the underlying
        servlet
/**
     * Gets the names of the methods supported by the underlying servlet.
     *
     * This is the same set of methods included in the Allow response header
     * in response to an OPTIONS request method processed by the underlying
     * servlet.
     *
     * @return Array of names of the methods supported by the underlying
     *         servlet
     *
     * @throws ServletException If the target servlet cannot be loaded
     */
    public String[] getServletMethods() throws ServletException;


    
Returns:true if this Servlet is currently unavailable.
/**
     * @return <code>true</code> if this Servlet is currently unavailable.
     */
    public boolean isUnavailable();


    
Returns:the associated Servlet instance.
/**
     * @return the associated Servlet instance.
     */
    public Servlet getServlet();


    
Set the associated Servlet instance

Params:
  • servlet – The associated Servlet
/**
     * Set the associated Servlet instance
     *
     * @param servlet The associated Servlet
     */
    public void setServlet(Servlet servlet);

    // --------------------------------------------------------- Public Methods


    
Add a new servlet initialization parameter for this servlet.

Params:
  • name – Name of this initialization parameter to add
  • value – Value of this initialization parameter to add
/**
     * Add a new servlet initialization parameter for this servlet.
     *
     * @param name Name of this initialization parameter to add
     * @param value Value of this initialization parameter to add
     */
    public void addInitParameter(String name, String value);


    
Add a mapping associated with the Wrapper.

Params:
  • mapping – The new wrapper mapping
/**
     * Add a mapping associated with the Wrapper.
     *
     * @param mapping The new wrapper mapping
     */
    public void addMapping(String mapping);


    
Add a new security role reference record to the set of records for
this servlet.

Params:
  • name – Role name used within this servlet
  • link – Role name used within the web application
/**
     * Add a new security role reference record to the set of records for
     * this servlet.
     *
     * @param name Role name used within this servlet
     * @param link Role name used within the web application
     */
    public void addSecurityReference(String name, String link);


    
Allocate an initialized instance of this Servlet that is ready to have
its service() method called.  If the Servlet class does
not implement SingleThreadModel, the (only) initialized
instance may be returned immediately.  If the Servlet class implements
SingleThreadModel, the Wrapper implementation must ensure
that this instance is not allocated again until it is deallocated by a
call to deallocate().

Throws:
  • ServletException – if the Servlet init() method threw
 an exception
  • ServletException – if a loading error occurs
Returns:a new Servlet instance
/**
     * Allocate an initialized instance of this Servlet that is ready to have
     * its <code>service()</code> method called.  If the Servlet class does
     * not implement <code>SingleThreadModel</code>, the (only) initialized
     * instance may be returned immediately.  If the Servlet class implements
     * <code>SingleThreadModel</code>, the Wrapper implementation must ensure
     * that this instance is not allocated again until it is deallocated by a
     * call to <code>deallocate()</code>.
     *
     * @exception ServletException if the Servlet init() method threw
     *  an exception
     * @exception ServletException if a loading error occurs
     * @return a new Servlet instance
     */
    public Servlet allocate() throws ServletException;


    
Return this previously allocated servlet to the pool of available
instances.  If this servlet class does not implement SingleThreadModel,
no action is actually required.

Params:
  • servlet – The servlet to be returned
Throws:
/**
     * Return this previously allocated servlet to the pool of available
     * instances.  If this servlet class does not implement SingleThreadModel,
     * no action is actually required.
     *
     * @param servlet The servlet to be returned
     *
     * @exception ServletException if a deallocation error occurs
     */
    public void deallocate(Servlet servlet) throws ServletException;


    
Params:
  • name – Name of the requested initialization parameter
Returns:the value for the specified initialization parameter name,
if any; otherwise return null.
/**
     * @return the value for the specified initialization parameter name,
     * if any; otherwise return <code>null</code>.
     *
     * @param name Name of the requested initialization parameter
     */
    public String findInitParameter(String name);


    
Returns:the names of all defined initialization parameters for this
servlet.
/**
     * @return the names of all defined initialization parameters for this
     * servlet.
     */
    public String[] findInitParameters();


    
Returns:the mappings associated with this wrapper.
/**
     * @return the mappings associated with this wrapper.
     */
    public String[] findMappings();


    
Params:
  • name – Security role reference used within this servlet
Returns:the security role link for the specified security role
reference name, if any; otherwise return null.
/**
     * @return the security role link for the specified security role
     * reference name, if any; otherwise return <code>null</code>.
     *
     * @param name Security role reference used within this servlet
     */
    public String findSecurityReference(String name);


    
Returns:the set of security role reference names associated with
this servlet, if any; otherwise return a zero-length array.
/**
     * @return the set of security role reference names associated with
     * this servlet, if any; otherwise return a zero-length array.
     */
    public String[] findSecurityReferences();


    
Increment the error count value used when monitoring.

/**
     * Increment the error count value used when monitoring.
     */
    public void incrementErrorCount();


    
Load and initialize an instance of this Servlet, if there is not already
at least one initialized instance.  This can be used, for example, to
load Servlets that are marked in the deployment descriptor to be loaded
at server startup time.

Throws:
  • ServletException – if the Servlet init() method threw
 an exception or if some other loading problem occurs
/**
     * Load and initialize an instance of this Servlet, if there is not already
     * at least one initialized instance.  This can be used, for example, to
     * load Servlets that are marked in the deployment descriptor to be loaded
     * at server startup time.
     *
     * @exception ServletException if the Servlet init() method threw
     *  an exception or if some other loading problem occurs
     */
    public void load() throws ServletException;


    
Remove the specified initialization parameter from this Servlet.

Params:
  • name – Name of the initialization parameter to remove
/**
     * Remove the specified initialization parameter from this Servlet.
     *
     * @param name Name of the initialization parameter to remove
     */
    public void removeInitParameter(String name);


    
Remove a mapping associated with the wrapper.

Params:
  • mapping – The pattern to remove
/**
     * Remove a mapping associated with the wrapper.
     *
     * @param mapping The pattern to remove
     */
    public void removeMapping(String mapping);


    
Remove any security role reference for the specified role name.

Params:
  • name – Security role used within this servlet to be removed
/**
     * Remove any security role reference for the specified role name.
     *
     * @param name Security role used within this servlet to be removed
     */
    public void removeSecurityReference(String name);


    
Process an UnavailableException, marking this Servlet as unavailable
for the specified amount of time.

Params:
  • unavailable – The exception that occurred, or null
 to mark this Servlet as permanently unavailable
/**
     * Process an UnavailableException, marking this Servlet as unavailable
     * for the specified amount of time.
     *
     * @param unavailable The exception that occurred, or <code>null</code>
     *  to mark this Servlet as permanently unavailable
     */
    public void unavailable(UnavailableException unavailable);


    
Unload all initialized instances of this servlet, after calling the
destroy() method for each instance.  This can be used,
for example, prior to shutting down the entire servlet engine, or
prior to reloading all of the classes from the Loader associated with
our Loader's repository.

Throws:
  • ServletException – if an unload error occurs
/**
     * Unload all initialized instances of this servlet, after calling the
     * <code>destroy()</code> method for each instance.  This can be used,
     * for example, prior to shutting down the entire servlet engine, or
     * prior to reloading all of the classes from the Loader associated with
     * our Loader's repository.
     *
     * @exception ServletException if an unload error occurs
     */
    public void unload() throws ServletException;


    
Returns:the multi-part configuration for the associated Servlet. If no
multi-part configuration has been defined, then null will be
returned.
/**
     * @return the multi-part configuration for the associated Servlet. If no
     * multi-part configuration has been defined, then <code>null</code> will be
     * returned.
     */
    public MultipartConfigElement getMultipartConfigElement();


    
Set the multi-part configuration for the associated Servlet. To clear the
multi-part configuration specify null as the new value.

Params:
  • multipartConfig – The configuration associated with the Servlet
/**
     * Set the multi-part configuration for the associated Servlet. To clear the
     * multi-part configuration specify <code>null</code> as the new value.
     *
     * @param multipartConfig The configuration associated with the Servlet
     */
    public void setMultipartConfigElement(
            MultipartConfigElement multipartConfig);

    
Does the associated Servlet support async processing? Defaults to
false.

Returns:true if the Servlet supports async
/**
     * Does the associated Servlet support async processing? Defaults to
     * <code>false</code>.
     *
     * @return <code>true</code> if the Servlet supports async
     */
    public boolean isAsyncSupported();

    
Set the async support for the associated Servlet.

Params:
  • asyncSupport – the new value
/**
     * Set the async support for the associated Servlet.
     *
     * @param asyncSupport the new value
     */
    public void setAsyncSupported(boolean asyncSupport);

    
Is the associated Servlet enabled? Defaults to true.

Returns:true if the Servlet is enabled
/**
     * Is the associated Servlet enabled? Defaults to <code>true</code>.
     *
     * @return <code>true</code> if the Servlet is enabled
     */
    public boolean isEnabled();

    
Sets the enabled attribute for the associated servlet.

Params:
  • enabled – the new value
/**
     * Sets the enabled attribute for the associated servlet.
     *
     * @param enabled the new value
     */
    public void setEnabled(boolean enabled);

    
Is the Servlet overridable by a ServletContainerInitializer?

Returns:true if the Servlet can be overridden in a ServletContainerInitializer
/**
     * Is the Servlet overridable by a ServletContainerInitializer?
     *
     * @return <code>true</code> if the Servlet can be overridden in a ServletContainerInitializer
     */
    public boolean isOverridable();

    
Sets the overridable attribute for this Servlet.

Params:
  • overridable – the new value
/**
     * Sets the overridable attribute for this Servlet.
     *
     * @param overridable the new value
     */
    public void setOverridable(boolean overridable);
}