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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.ee8.nested;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* ScopedHandler.
*
* A ScopedHandler is a HandlerWrapper where the wrapped handlers
* each define a scope.
*
* When {@link #handle(String, Request, HttpServletRequest, HttpServletResponse)}
* is called on the first ScopedHandler in a chain of HandlerWrappers,
* the {@link #doScope(String, Request, HttpServletRequest, HttpServletResponse)} method is
* called on all contained ScopedHandlers, before the
* {@link #doHandle(String, Request, HttpServletRequest, HttpServletResponse)} method
* is called on all contained handlers.
*
* For example if Scoped handlers A, B & C were chained together, then
* the calling order would be:
*
* A.handle(...)
* A.doScope(...)
* B.doScope(...)
* C.doScope(...)
* A.doHandle(...)
* B.doHandle(...)
* C.doHandle(...)
*
*
* If non scoped handler X was in the chained A, B, X & C, then
* the calling order would be:
*
* A.handle(...)
* A.doScope(...)
* B.doScope(...)
* C.doScope(...)
* A.doHandle(...)
* B.doHandle(...)
* X.handle(...)
* C.handle(...)
* C.doHandle(...)
*
*
* A typical usage pattern is:
*
* private static class MyHandler extends ScopedHandler
* {
* public void doScope(String target, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
* {
* try
* {
* setUpMyScope();
* super.doScope(target,request,response);
* }
* finally
* {
* tearDownMyScope();
* }
* }
*
* public void doHandle(String target, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
* {
* try
* {
* doMyHandling();
* super.doHandle(target,request,response);
* }
* finally
* {
* cleanupMyHandling();
* }
* }
* }
*
*/
public abstract class ScopedHandler extends HandlerWrapper {
private static final ThreadLocal __outerScope = new ThreadLocal<>();
protected ScopedHandler _outerScope;
protected ScopedHandler _nextScope;
@Override
protected void doStart() throws Exception {
try {
_outerScope = __outerScope.get();
if (_outerScope == null)
__outerScope.set(this);
super.doStart();
_nextScope = getChildHandlerByClass(ScopedHandler.class);
} finally {
if (_outerScope == null)
__outerScope.set(null);
}
}
@Override
public final void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
if (isStarted()) {
if (_outerScope == null)
doScope(target, baseRequest, request, response);
else
doHandle(target, baseRequest, request, response);
}
}
/**
* Scope the handler
* Derived implementations should call {@link #nextScope(String, Request, HttpServletRequest, HttpServletResponse)}
*
* @param target The target of the request - either a URI or a name.
* @param baseRequest The original unwrapped request object.
* @param request The request either as the {@link Request} object or a wrapper of that request.
* @param response The response as the {@link Response} object or a wrapper of that request.
* @throws IOException if unable to handle the request or response processing
* @throws ServletException if unable to handle the request or response due to underlying servlet issue
*/
public void doScope(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
nextScope(target, baseRequest, request, response);
}
/**
* Scope the handler
*
* @param target The target of the request - either a URI or a name.
* @param baseRequest The original unwrapped request object.
* @param request The request either as the {@link Request} object or a wrapper of that request.
* @param response The response as the {@link Response} object or a wrapper of that request.
* @throws IOException if unable to handle the request or response processing
* @throws ServletException if unable to handle the request or response due to underlying servlet issue
*/
public final void nextScope(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
if (_nextScope != null)
_nextScope.doScope(target, baseRequest, request, response);
else if (_outerScope != null)
_outerScope.doHandle(target, baseRequest, request, response);
else
doHandle(target, baseRequest, request, response);
}
/**
* Do the handler work within the scope.
*
Derived implementations should call {@link #nextHandle(String, Request, HttpServletRequest, HttpServletResponse)}
*
* @param target The target of the request - either a URI or a name.
* @param baseRequest The original unwrapped request object.
* @param request The request either as the {@link Request} object or a wrapper of that request.
* @param response The response as the {@link Response} object or a wrapper of that request.
* @throws IOException if unable to handle the request or response processing
* @throws ServletException if unable to handle the request or response due to underlying servlet issue
*/
public abstract void doHandle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException;
/**
* Do the handler work within the scope.
* @param target The target of the request - either a URI or a name.
* @param baseRequest The original unwrapped request object.
* @param request The request either as the {@link Request} object or a wrapper of that request.
* @param response The response as the {@link Response} object or a wrapper of that request.
* @throws IOException if unable to handle the request or response processing
* @throws ServletException if unable to handle the request or response due to underlying servlet issue
*/
public final void nextHandle(String target, final Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
if (_nextScope != null && _nextScope == _handler)
_nextScope.doHandle(target, baseRequest, request, response);
else if (_handler != null)
super.handle(target, baseRequest, request, response);
}
}