/*
* Copyright (C) 2008 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 static com.google.inject.servlet.ManagedServletPipeline.REQUEST_DISPATCHER_REQUEST;
import com.google.common.base.Strings;
import com.google.common.collect.Iterators;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Scopes;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderWithExtensionVisitor;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
/**
* Defines a servlet mapped to a URI pattern and performs the request dispatch to that servlet.
*
* @author dhanji@gmail.com (Dhanji R. Prasanna)
*/
public class ServletDefinition implements ProviderWithExtensionVisitor<ServletDefinition> {
private static final Logger logger = Logger.getLogger(ServletDefinition.class.getName());
private final Key<? extends HttpServlet> servletKey;
private final UriPatternMatcher patternMatcher;
private final Map<String, String> initParams;
// set only if this was bound using a servlet instance.
private final HttpServlet servletInstance;
//always set in init, our servlet is always presumed to be a singleton
private final AtomicReference<HttpServlet> httpServlet = new AtomicReference<HttpServlet>();
public ServletDefinition(
Key<? extends HttpServlet> servletKey,
UriPatternMatcher patternMatcher,
Map<String, String> initParams,
HttpServlet servletInstance) {
this.servletKey = servletKey;
this.patternMatcher = patternMatcher;
this.initParams = Collections.unmodifiableMap(new HashMap<String, String>(initParams));
this.servletInstance = servletInstance;
}
@Override
public ServletDefinition get() {
return this;
}
@Override
public <B, V> V acceptExtensionVisitor(
BindingTargetVisitor<B, V> visitor, ProviderInstanceBinding<? extends B> binding) {
if (visitor instanceof ServletModuleTargetVisitor) {
if (servletInstance != null) {
return ((ServletModuleTargetVisitor<B, V>) visitor)
.visit(new InstanceServletBindingImpl(initParams, servletInstance, patternMatcher));
} else {
return ((ServletModuleTargetVisitor<B, V>) visitor)
.visit(new LinkedServletBindingImpl(initParams, servletKey, patternMatcher));
}
} else {
return visitor.visit(binding);
}
}
boolean shouldServe(String uri) {
return uri != null && patternMatcher.matches(uri);
}
void init(
final ServletContext servletContext, Injector injector, Set<HttpServlet> initializedSoFar)
throws ServletException {
// This absolutely must be a singleton, and so is only initialized once.
if (!Scopes.isSingleton(injector.getBinding(servletKey))) {
throw new ServletException(
"Servlets must be bound as singletons. "
+ servletKey
+ " was not bound in singleton scope.");
}
HttpServlet httpServlet = injector.getInstance(servletKey);
this.httpServlet.set(httpServlet);
// Only fire init() if we have not appeared before in the filter chain.
if (initializedSoFar.contains(httpServlet)) {
return;
}
//initialize our servlet with the configured context params and servlet context
httpServlet.init(
new ServletConfig() {
@Override
public String getServletName() {
return servletKey.toString();
}
@Override
public ServletContext getServletContext() {
return servletContext;
}
@Override
public String getInitParameter(String s) {
return initParams.get(s);
}
@Override
public Enumeration getInitParameterNames() {
return Iterators.asEnumeration(initParams.keySet().iterator());
}
});
// Mark as initialized.
initializedSoFar.add(httpServlet);
}
void destroy(Set<HttpServlet> destroyedSoFar) {
HttpServlet reference = httpServlet.get();
// Do nothing if this Servlet was invalid (usually due to not being scoped
// properly). According to Servlet Spec: it is "out of service", and does not
// need to be destroyed.
// Also prevent duplicate destroys to the same singleton that may appear
// more than once on the filter chain.
if (null == reference || destroyedSoFar.contains(reference)) {
return;
}
try {
reference.destroy();
} finally {
destroyedSoFar.add(reference);
}
}
/**
* Wrapper around the service chain to ensure a servlet is servicing what it must and provides it
* with a wrapped request.
*
* @return Returns true if this servlet triggered for the given request. Or false if guice-servlet
* should continue dispatching down the servlet pipeline.
* @throws IOException If thrown by underlying servlet
* @throws ServletException If thrown by underlying servlet
*/
boolean service(ServletRequest servletRequest, ServletResponse servletResponse)
throws IOException, ServletException {
final HttpServletRequest request = (HttpServletRequest) servletRequest;
final String path = ServletUtils.getContextRelativePath(request);
final boolean serve = shouldServe(path);
//invocations of the chain end at the first matched servlet
if (serve) {
doService(servletRequest, servletResponse);
}
//return false if no servlet matched (so we can proceed down to the web.xml servlets)
return serve;
}
/**
* Utility that delegates to the actual service method of the servlet wrapped with a contextual
* request (i.e. with correctly computed path info).
*
* <p>We need to suppress deprecation coz we use HttpServletRequestWrapper, which implements
* deprecated API for backwards compatibility.
*/
void doService(final ServletRequest servletRequest, ServletResponse servletResponse)
throws ServletException, IOException {
HttpServletRequest request =
new HttpServletRequestWrapper((HttpServletRequest) servletRequest) {
private boolean pathComputed;
private String path;
private boolean pathInfoComputed;
private String pathInfo;
@Override
public String getPathInfo() {
if (!isPathInfoComputed()) {
String servletPath = getServletPath();
int servletPathLength = servletPath.length();
String requestUri = getRequestURI();
pathInfo = requestUri.substring(getContextPath().length()).replaceAll("[/]{2,}", "/");
// See: https://github.com/google/guice/issues/372
if (pathInfo.startsWith(servletPath)) {
pathInfo = pathInfo.substring(servletPathLength);
// Corner case: when servlet path & request path match exactly (without trailing '/'),
// then pathinfo is null.
if (pathInfo.isEmpty() && servletPathLength > 0) {
pathInfo = null;
} else {
try {
pathInfo = new URI(pathInfo).getPath();
} catch (URISyntaxException e) {
// ugh, just leave it alone then
}
}
} else {
pathInfo = null; // we know nothing additional about the URI.
}
pathInfoComputed = true;
}
return pathInfo;
}
// NOTE(dhanji): These two are a bit of a hack to help ensure that request dispatcher-sent
// requests don't use the same path info that was memoized for the original request.
// NOTE(iqshum): I don't think this is possible, since the dispatcher-sent request would
// perform its own wrapping.
private boolean isPathInfoComputed() {
return pathInfoComputed
&& servletRequest.getAttribute(REQUEST_DISPATCHER_REQUEST) == null;
}
private boolean isPathComputed() {
return pathComputed && servletRequest.getAttribute(REQUEST_DISPATCHER_REQUEST) == null;
}
@Override
public String getServletPath() {
return computePath();
}
@Override
public String getPathTranslated() {
final String info = getPathInfo();
return (null == info) ? null : getRealPath(info);
}
// Memoizer pattern.
private String computePath() {
if (!isPathComputed()) {
String servletPath = super.getServletPath();
path = patternMatcher.extractPath(servletPath);
pathComputed = true;
if (null == path) {
path = servletPath;
}
}
return path;
}
};
doServiceImpl(request, (HttpServletResponse) servletResponse);
}
private void doServiceImpl(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
GuiceFilter.Context previous = GuiceFilter.localContext.get();
HttpServletRequest originalRequest =
(previous != null) ? previous.getOriginalRequest() : request;
GuiceFilter.localContext.set(new GuiceFilter.Context(originalRequest, request, response));
try {
HttpServlet reference = httpServlet.get();
if (logger.isLoggable(Level.FINEST)) {
String path = ServletUtils.getContextRelativePath(request);
logger.finest("Serving " + path + " with " + reference);
}
if (reference != null) {
reference.service(request, response);
}
} finally {
GuiceFilter.localContext.set(previous);
}
}
String getKey() {
return servletKey.toString();
}
public String toPaddedString(int padding) {
HttpServlet reference = httpServlet.get();
return Strings.padEnd(patternMatcher.getOriginalPattern(), padding, ' ') + ' '
+ (reference != null ? reference : servletKey);
}
}