/**
* Copyright (C) 2006 Google Inc.
*
* 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
*
* http://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 com.google.inject.servlet;
import com.google.inject.Inject;
import com.google.inject.OutOfScopeException;
import com.google.inject.Stage;
import java.io.IOException;
import java.lang.ref.WeakReference;
import java.util.logging.Logger;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* <p>
* Apply this filter in web.xml above all other filters (typically), to all requests where you plan
* to use servlet scopes. This is also needed in order to dispatch requests to injectable filters
* and servlets:
* <pre>
* <filter>
* <filter-name>guiceFilter</filter-name>
* <filter-class><b>com.google.inject.servlet.GuiceFilter</b></filter-class>
* </filter>
*
* <filter-mapping>
* <filter-name>guiceFilter</filter-name>
* <url-pattern>/*</url-pattern>
* </filter-mapping>
* </pre>
*
* This filter must appear before every filter that makes use of Guice injection or servlet
* scopes functionality. Typically, you will only register this filter in web.xml and register
* any other filters (and servlets) using a {@link ServletModule}.
*
* @author crazybob@google.com (Bob Lee)
* @author dhanji@gmail.com (Dhanji R. Prasanna)
*/
public class GuiceFilter implements Filter {
static final ThreadLocal<Context> localContext = new ThreadLocal<Context>();
static volatile FilterPipeline pipeline = new DefaultFilterPipeline();
/** Used to inject the servlets configured via {@link ServletModule} */
static volatile WeakReference<ServletContext> servletContext =
new WeakReference<ServletContext>(null);
private static final String MULTIPLE_INJECTORS_ERROR =
"Multiple injectors detected. Please install only one"
+ " ServletModule in your web application. While you may "
+ "have more than one injector, you should only configure"
+ " guice-servlet in one of them. (Hint: look for legacy "
+ "ServetModules or multiple calls to Servlets.configure()).";
//VisibleForTesting
@Inject
static void setPipeline(FilterPipeline pipeline, Stage stage) {
// Multiple injectors with Servlet pipelines?!
// We don't throw an exception in DEVELOPMENT stage, to allow for legacy
// tests that don't have a tearDown that calls GuiceFilter#destroy().
if (GuiceFilter.pipeline instanceof ManagedFilterPipeline) {
if (Stage.PRODUCTION.equals(stage)) {
throw new RuntimeException(MULTIPLE_INJECTORS_ERROR);
} else {
Logger.getLogger(GuiceFilter.class.getName()).warning(MULTIPLE_INJECTORS_ERROR);
}
}
// We overwrite the default pipeline
GuiceFilter.pipeline = pipeline;
}
//VisibleForTesting
static void reset() {
pipeline = new DefaultFilterPipeline();
}
public void doFilter(ServletRequest servletRequest,
ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
Context previous = localContext.get();
FilterPipeline filterPipeline = pipeline;
try {
localContext.set(new Context((HttpServletRequest) servletRequest,
(HttpServletResponse) servletResponse));
//dispatch across the servlet pipeline, ensuring web.xml's filterchain is honored
filterPipeline.dispatch(servletRequest, servletResponse, filterChain);
} finally {
localContext.set(previous);
}
}
static HttpServletRequest getRequest() {
return getContext().getRequest();
}
static HttpServletResponse getResponse() {
return getContext().getResponse();
}
static ServletContext getServletContext() {
return servletContext.get();
}
static Context getContext() {
Context context = localContext.get();
if (context == null) {
throw new OutOfScopeException("Cannot access scoped object. Either we"
+ " are not currently inside an HTTP Servlet request, or you may"
+ " have forgotten to apply " + GuiceFilter.class.getName()
+ " as a servlet filter for this request.");
}
return context;
}
static class Context {
final HttpServletRequest request;
final HttpServletResponse response;
Context(HttpServletRequest request, HttpServletResponse response) {
this.request = request;
this.response = response;
}
HttpServletRequest getRequest() {
return request;
}
HttpServletResponse getResponse() {
return response;
}
}
public void init(FilterConfig filterConfig) throws ServletException {
final ServletContext servletContext = filterConfig.getServletContext();
// Store servlet context in a weakreference, for injection
GuiceFilter.servletContext = new WeakReference<ServletContext>(servletContext);
// In the default pipeline, this is a noop. However, if replaced
// by a managed pipeline, a lazy init will be triggered the first time
// dispatch occurs.
GuiceFilter.pipeline.initPipeline(servletContext);
}
public void destroy() {
try {
// Destroy all registered filters & servlets in that order
pipeline.destroyPipeline();
} finally {
reset();
servletContext.clear();
}
}
}