ChainInit.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* 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
* 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 org.apache.commons.chain.web.javax;
import java.io.InputStream;
import java.net.URL;
import java.util.Collections;
import java.util.Iterator;
import java.util.Set;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import org.apache.commons.chain.Catalog;
import org.apache.commons.chain.CatalogFactory;
import org.apache.commons.chain.config.ConfigParser;
import org.apache.commons.chain.impl.CatalogBase;
import org.apache.commons.chain.web.CheckedConsumer;
import org.apache.commons.digester.RuleSet;
import org.slf4j.Logger;
/**
* Context-initializer that automatically scans chain configuration files
* in the current web application at startup time, and exposes the result
* in a {@link Catalog} under a specified servlet context attribute. The
* following <em>context</em> init parameters are utilized:
* <ul>
* <li><strong>org.apache.commons.chain.CONFIG_CLASS_RESOURCE</strong> -
* comma-delimited list of chain configuration resources to be loaded
* via {@code ClassLoader.getResource()} calls. If not specified,
* no class loader resources will be loaded.</li>
* <li><strong>org.apache.commons.chain.CONFIG_WEB_RESOURCE</strong> -
* comma-delimited list of chain configuration webapp resources
* to be loaded. If not specified, no web application resources
* will be loaded.</li>
* <li><strong>org.apache.commons.chain.CONFIG_ATTR</strong> -
* Name of the servlet context attribute under which the
* resulting {@link Catalog} will be created or updated.
* If not specified, it is expected that parsed resources will
* contain {@code <catalog>} elements (which will
* cause registration of the created {@link Catalog}s into
* the {@link CatalogFactory} for this application, and no
* servet context attribute will be created.
* <strong>NOTE</strong> - This parameter is deprecated.</li>
* <li><strong>org.apache.commons.chain.RULE_SET</strong> -
* Fully qualified class name of a Digester {@code RuleSet}
* implementation to use for parsing configuration resources (this
* class must have a public zero-args constructor). If not defined,
* the standard {@code RuleSet} implementation will be used.</li>
* </ul>
*
* <p>When a web application that has configured this listener is
* started, it will acquire the {@link Catalog} under the specified servlet
* context attribute key, creating a new one if there is none already there.
* This {@link Catalog} will then be populated by scanning configuration
* resources from the following sources (loaded in this order):</p>
* <ul>
* <li>Optional: Resources loaded from any {@code META-INF/chain-config.xml}
* resource found in a JAR file in {@code /WEB-INF/lib}.</li>
* <li>Resources loaded from specified resource paths from the
* webapp's class loader (via {@code ClassLoader.getResource()}).</li>
* <li>Resources loaded from specified resource paths in the web application
* archive (via {@code ServetContext.getResource()}).</li>
* </ul>
*
* <p>If no attribute key is specified, on the other hand, parsed configuration
* resources are expected to contain {@code <catalog>} elements,
* and the catalogs will be registered with the {@link CatalogFactory}
* for this web application.</p>
*
* @author Craig R. McClanahan
* @author Ted Husted
*/
final class ChainInit {
/**
* The name of the context init parameter containing the name of the
* servlet context attribute under which our resulting {@link Catalog}
* will be stored.
*/
static final String CONFIG_ATTR =
"org.apache.commons.chain.CONFIG_ATTR";
/**
* The name of the context init parameter containing a comma-delimited
* list of class loader resources to be scanned.
*/
static final String CONFIG_CLASS_RESOURCE =
"org.apache.commons.chain.CONFIG_CLASS_RESOURCE";
/**
* The name of the context init parameter containing a comma-delimited
* list of web application resources to be scanned.
*/
static final String CONFIG_WEB_RESOURCE =
"org.apache.commons.chain.CONFIG_WEB_RESOURCE";
/**
* The name of the context init parameter containing the fully
* qualified class name of the {@code RuleSet} implementation
* for configuring our {@link ConfigParser}.
*/
static final String RULE_SET =
"org.apache.commons.chain.RULE_SET";
/**
* Remove the configured {@link Catalog} from the servlet context
* attributes for this web application.
*
* @param context the servlet-context
* @param attr the value of the {@code CONFIG_ATTR}
*/
static void destroy(ServletContext context, String attr) {
if (attr != null) {
context.removeAttribute(attr);
}
CatalogFactory.clear();
}
/**
* Private constructor.
*/
private ChainInit() {
}
/**
* Scan the required chain configuration resources, assemble the
* configured chains into a {@link Catalog}, and expose it as a
* servlet context attribute under the specified key.
*
* @param context the servlet-context
* @param attr the value of the {@code CONFIG_ATTR}
* @param logger to use for logging
* @param parseJarResources {@code true} to parse resources in jar-files
*/
@SuppressWarnings("deprecation")
static void initialize(ServletContext context, String attr, Logger logger, boolean parseJarResources) throws ServletException {
String classResources = context.getInitParameter(CONFIG_CLASS_RESOURCE);
String ruleSet = context.getInitParameter(RULE_SET);
String webResources = context.getInitParameter(CONFIG_WEB_RESOURCE);
// Retrieve or create the Catalog instance we may be updating
Catalog<?> catalog = null;
if (attr != null) {
catalog = (Catalog<?>) context.getAttribute(attr);
if (catalog == null) {
catalog = new CatalogBase<>();
}
}
// Construct the configuration resource parser we will use
ConfigParser parser = new ConfigParser();
if (ruleSet != null) {
try {
ClassLoader loader =
Thread.currentThread().getContextClassLoader();
if (loader == null) {
loader = ChainInit.class.getClassLoader();
}
Class<? extends RuleSet> clazz = loader
.loadClass(ruleSet)
.asSubclass(RuleSet.class);
parser.setRuleSet(clazz.getDeclaredConstructor().newInstance());
} catch (Exception e) {
throw new ServletException("Exception initalizing RuleSet '"
+ ruleSet + "' instance ", e);
}
}
// Parse the resources specified in our init parameters (if any)
final CheckedConsumer<URL, Exception> parse;
if (attr == null) {
parse = parser::parse;
} else {
final Catalog<?> cat = catalog;
parse = url -> parser.parse(cat, url);
}
if (parseJarResources) {
parseJarResources(context, parse, logger);
}
ChainResources.parseClassResources(classResources, parse);
ChainResources.parseWebResources(context, webResources, parse);
// Expose the completed catalog (if requested)
if (attr != null) {
context.setAttribute(attr, catalog);
}
}
// --------------------------------------------------------- Private Methods
/**
* Parse resources found in JAR files in the {@code /WEB-INF/lib}
* subdirectory (if any).
*
* @param <E> the type of the exception from parse-function
* @param context {@code ServletContext} for this web application
* @param parse parse-function to parse the XML document
* @param logger to use for logging
*/
private static <E extends Exception> void parseJarResources(ServletContext context,
CheckedConsumer<URL, E> parse, Logger logger) {
Set<String> jars = context.getResourcePaths("/WEB-INF/lib");
if (jars == null) {
jars = Collections.emptySet();
}
String path = null;
Iterator<String> paths = jars.iterator();
while (paths.hasNext()) {
path = paths.next();
if (!path.endsWith(".jar")) {
continue;
}
URL resourceURL = null;
try {
URL jarURL = context.getResource(path);
path = jarURL.toExternalForm();
resourceURL = new URL("jar:"
+ translate(path)
+ "!/META-INF/chain-config.xml");
path = resourceURL.toExternalForm();
InputStream is = null;
try {
is = resourceURL.openStream();
} catch (Exception e) {
// means there is no such resource
logger.atTrace().setMessage("OpenStream: {}").addArgument(resourceURL).setCause(e).log();
}
if (is == null) {
logger.debug("Not Found: {}", resourceURL);
continue;
} else {
is.close();
}
logger.debug("Parsing: {}", resourceURL);
parse.accept(resourceURL);
} catch (Exception e) {
throw new RuntimeException("Exception parsing chain config resource '"
+ path + "': " + e.getMessage());
}
}
}
/**
* Translate space character into {@code %20} to avoid problems
* with paths that contain spaces on some JVMs.
*
* @param value Value to translate
*
* @return the translated value
*/
private static String translate(String value) {
while (true) {
int index = value.indexOf(' ');
if (index < 0) {
break;
}
value = value.substring(0, index) + "%20" + value.substring(index + 1);
}
return value;
}
}