/*
* Copyright 2002-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.filter;
import java.io.IOException;
import javax.servlet.DispatcherType;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.context.request.async.WebAsyncManager;
import org.springframework.web.context.request.async.WebAsyncUtils;
import org.springframework.web.util.WebUtils;
Filter base class that aims to guarantee a single execution per request dispatch, on any servlet container. It provides a doFilterInternal method with HttpServletRequest and HttpServletResponse arguments. As of Servlet 3.0, a filter may be invoked as part of a REQUEST or ASYNC dispatches that occur in separate threads. A filter can be configured in web.xml whether it should be involved in async dispatches. However, in some cases servlet containers assume different default configuration. Therefore sub-classes can override the method shouldNotFilterAsyncDispatch() to declare statically if they should indeed be invoked, once, during both types of dispatches in order to provide thread initialization, logging, security, and so on. This mechanism complements and does not replace the need to configure a filter in web.xml with dispatcher types.
Subclasses may use isAsyncDispatch(HttpServletRequest) to determine when a filter is invoked as part of an async dispatch, and use isAsyncStarted(HttpServletRequest) to determine when the request has been placed in async mode and therefore the current dispatch won't be the last one for the given request.
Yet another dispatch type that also occurs in its own thread is ERROR. Subclasses can override shouldNotFilterErrorDispatch() if they wish to declare statically if they should be invoked once during error dispatches.
The getAlreadyFilteredAttributeName method determines how to identify that a request is already filtered. The default implementation is based on the configured name of the concrete filter instance.
Author: Juergen Hoeller, Rossen Stoyanchev Since: 06.12.2003
/**
* Filter base class that aims to guarantee a single execution per request
* dispatch, on any servlet container. It provides a {@link #doFilterInternal}
* method with HttpServletRequest and HttpServletResponse arguments.
*
* <p>As of Servlet 3.0, a filter may be invoked as part of a
* {@link javax.servlet.DispatcherType#REQUEST REQUEST} or
* {@link javax.servlet.DispatcherType#ASYNC ASYNC} dispatches that occur in
* separate threads. A filter can be configured in {@code web.xml} whether it
* should be involved in async dispatches. However, in some cases servlet
* containers assume different default configuration. Therefore sub-classes can
* override the method {@link #shouldNotFilterAsyncDispatch()} to declare
* statically if they should indeed be invoked, <em>once</em>, during both types
* of dispatches in order to provide thread initialization, logging, security,
* and so on. This mechanism complements and does not replace the need to
* configure a filter in {@code web.xml} with dispatcher types.
*
* <p>Subclasses may use {@link #isAsyncDispatch(HttpServletRequest)} to
* determine when a filter is invoked as part of an async dispatch, and use
* {@link #isAsyncStarted(HttpServletRequest)} to determine when the request
* has been placed in async mode and therefore the current dispatch won't be
* the last one for the given request.
*
* <p>Yet another dispatch type that also occurs in its own thread is
* {@link javax.servlet.DispatcherType#ERROR ERROR}. Subclasses can override
* {@link #shouldNotFilterErrorDispatch()} if they wish to declare statically
* if they should be invoked <em>once</em> during error dispatches.
*
* <p>The {@link #getAlreadyFilteredAttributeName} method determines how to
* identify that a request is already filtered. The default implementation is
* based on the configured name of the concrete filter instance.
*
* @author Juergen Hoeller
* @author Rossen Stoyanchev
* @since 06.12.2003
*/
public abstract class OncePerRequestFilter extends GenericFilterBean {
Suffix that gets appended to the filter name for the
"already filtered" request attribute.
See Also: - getAlreadyFilteredAttributeName
/**
* Suffix that gets appended to the filter name for the
* "already filtered" request attribute.
* @see #getAlreadyFilteredAttributeName
*/
public static final String ALREADY_FILTERED_SUFFIX = ".FILTERED";
This doFilter implementation stores a request attribute for "already filtered", proceeding without filtering again if the attribute is already there. See Also: - getAlreadyFilteredAttributeName
- shouldNotFilter
- doFilterInternal
/**
* This {@code doFilter} implementation stores a request attribute for
* "already filtered", proceeding without filtering again if the
* attribute is already there.
* @see #getAlreadyFilteredAttributeName
* @see #shouldNotFilter
* @see #doFilterInternal
*/
@Override
public final void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
throw new ServletException("OncePerRequestFilter just supports HTTP requests");
}
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;
String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();
boolean hasAlreadyFilteredAttribute = request.getAttribute(alreadyFilteredAttributeName) != null;
if (skipDispatch(httpRequest) || shouldNotFilter(httpRequest)) {
// Proceed without invoking this filter...
filterChain.doFilter(request, response);
}
else if (hasAlreadyFilteredAttribute) {
if (DispatcherType.ERROR.equals(request.getDispatcherType())) {
doFilterNestedErrorDispatch(httpRequest, httpResponse, filterChain);
return;
}
// Proceed without invoking this filter...
filterChain.doFilter(request, response);
}
else {
// Do invoke this filter...
request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);
try {
doFilterInternal(httpRequest, httpResponse, filterChain);
}
finally {
// Remove the "already filtered" request attribute for this request.
request.removeAttribute(alreadyFilteredAttributeName);
}
}
}
private boolean skipDispatch(HttpServletRequest request) {
if (isAsyncDispatch(request) && shouldNotFilterAsyncDispatch()) {
return true;
}
if (request.getAttribute(WebUtils.ERROR_REQUEST_URI_ATTRIBUTE) != null && shouldNotFilterErrorDispatch()) {
return true;
}
return false;
}
The dispatcher type javax.servlet.DispatcherType.ASYNC introduced in Servlet 3.0 means a filter can be invoked in more than one thread over the course of a single request. This method returns true if the filter is currently executing within an asynchronous dispatch. Params: - request – the current request
See Also: Since: 3.2
/**
* The dispatcher type {@code javax.servlet.DispatcherType.ASYNC} introduced
* in Servlet 3.0 means a filter can be invoked in more than one thread over
* the course of a single request. This method returns {@code true} if the
* filter is currently executing within an asynchronous dispatch.
* @param request the current request
* @since 3.2
* @see WebAsyncManager#hasConcurrentResult()
*/
protected boolean isAsyncDispatch(HttpServletRequest request) {
return request.getDispatcherType().equals(DispatcherType.ASYNC);
}
Whether request processing is in asynchronous mode meaning that the
response will not be committed after the current thread is exited.
Params: - request – the current request
See Also: Since: 3.2
/**
* Whether request processing is in asynchronous mode meaning that the
* response will not be committed after the current thread is exited.
* @param request the current request
* @since 3.2
* @see WebAsyncManager#isConcurrentHandlingStarted()
*/
protected boolean isAsyncStarted(HttpServletRequest request) {
return WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted();
}
Return the name of the request attribute that identifies that a request
is already filtered.
The default implementation takes the configured name of the concrete filter
instance and appends ".FILTERED". If the filter is not fully initialized,
it falls back to its class name.
See Also: - getFilterName
- ALREADY_FILTERED_SUFFIX
/**
* Return the name of the request attribute that identifies that a request
* is already filtered.
* <p>The default implementation takes the configured name of the concrete filter
* instance and appends ".FILTERED". If the filter is not fully initialized,
* it falls back to its class name.
* @see #getFilterName
* @see #ALREADY_FILTERED_SUFFIX
*/
protected String getAlreadyFilteredAttributeName() {
String name = getFilterName();
if (name == null) {
name = getClass().getName();
}
return name + ALREADY_FILTERED_SUFFIX;
}
Can be overridden in subclasses for custom filtering control, returning true to avoid filtering of the given request. The default implementation always returns false.
Params: - request – current HTTP request
Throws: - ServletException – in case of errors
Returns: whether the given request should not be filtered
/**
* Can be overridden in subclasses for custom filtering control,
* returning {@code true} to avoid filtering of the given request.
* <p>The default implementation always returns {@code false}.
* @param request current HTTP request
* @return whether the given request should <i>not</i> be filtered
* @throws ServletException in case of errors
*/
protected boolean shouldNotFilter(HttpServletRequest request) throws ServletException {
return false;
}
The dispatcher type javax.servlet.DispatcherType.ASYNC introduced in Servlet 3.0 means a filter can be invoked in more than one thread over the course of a single request. Some filters only need to filter the initial thread (e.g. request wrapping) while others may need to be invoked at least once in each additional thread for example for setting up thread locals or to perform final processing at the very end. Note that although a filter can be mapped to handle specific dispatcher types via web.xml or in Java through the ServletContext, servlet containers may enforce different defaults with regards to dispatcher types. This flag enforces the design intent of the filter.
The default return value is "true", which means the filter will not be
invoked during subsequent async dispatches. If "false", the filter will
be invoked during async dispatches with the same guarantees of being
invoked only once during a request within a single thread.
Since: 3.2
/**
* The dispatcher type {@code javax.servlet.DispatcherType.ASYNC} introduced
* in Servlet 3.0 means a filter can be invoked in more than one thread
* over the course of a single request. Some filters only need to filter
* the initial thread (e.g. request wrapping) while others may need
* to be invoked at least once in each additional thread for example for
* setting up thread locals or to perform final processing at the very end.
* <p>Note that although a filter can be mapped to handle specific dispatcher
* types via {@code web.xml} or in Java through the {@code ServletContext},
* servlet containers may enforce different defaults with regards to
* dispatcher types. This flag enforces the design intent of the filter.
* <p>The default return value is "true", which means the filter will not be
* invoked during subsequent async dispatches. If "false", the filter will
* be invoked during async dispatches with the same guarantees of being
* invoked only once during a request within a single thread.
* @since 3.2
*/
protected boolean shouldNotFilterAsyncDispatch() {
return true;
}
Whether to filter error dispatches such as when the servlet container processes and error mapped in web.xml. The default return value is "true", which means the filter will not be invoked in case of an error dispatch. Since: 3.2
/**
* Whether to filter error dispatches such as when the servlet container
* processes and error mapped in {@code web.xml}. The default return value
* is "true", which means the filter will not be invoked in case of an error
* dispatch.
* @since 3.2
*/
protected boolean shouldNotFilterErrorDispatch() {
return true;
}
Same contract as for doFilter, but guaranteed to be just invoked once per request within a single request thread. See shouldNotFilterAsyncDispatch() for details. Provides HttpServletRequest and HttpServletResponse arguments instead of the
default ServletRequest and ServletResponse ones.
/**
* Same contract as for {@code doFilter}, but guaranteed to be
* just invoked once per request within a single request thread.
* See {@link #shouldNotFilterAsyncDispatch()} for details.
* <p>Provides HttpServletRequest and HttpServletResponse arguments instead of the
* default ServletRequest and ServletResponse ones.
*/
protected abstract void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException;
Typically an ERROR dispatch happens after the REQUEST dispatch completes, and the filter chain starts anew. On some servers however the ERROR dispatch may be nested within the REQUEST dispatch, e.g. as a result of calling sendError on the response. In that case we are still in the filter chain, on the same thread, but the request and response have been switched to the original, unwrapped ones. Sub-classes may use this method to filter such nested ERROR dispatches and re-apply wrapping on the request or response. ThreadLocal context, if any, should still be active as we are still nested within the filter chain.
Since: 5.1.9
/**
* Typically an ERROR dispatch happens after the REQUEST dispatch completes,
* and the filter chain starts anew. On some servers however the ERROR
* dispatch may be nested within the REQUEST dispatch, e.g. as a result of
* calling {@code sendError} on the response. In that case we are still in
* the filter chain, on the same thread, but the request and response have
* been switched to the original, unwrapped ones.
* <p>Sub-classes may use this method to filter such nested ERROR dispatches
* and re-apply wrapping on the request or response. {@code ThreadLocal}
* context, if any, should still be active as we are still nested within
* the filter chain.
* @since 5.1.9
*/
protected void doFilterNestedErrorDispatch(HttpServletRequest request, HttpServletResponse response,
FilterChain filterChain) throws ServletException, IOException {
filterChain.doFilter(request, response);
}
}