com.netbout.spi.cpa.OpDiscoverer Maven / Gradle / Ivy
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/**
* Copyright (c) 2009-2012, Netbout.com
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met: 1) Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer. 2) Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution. 3) Neither the name of the NetBout.com nor
* the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.netbout.spi.cpa;
import com.jcabi.log.Logger;
import com.netbout.spi.Identity;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.reflections.Reflections;
/**
* Discovers operations in classpath.
*
* @author Yegor Bugayenko ([email protected])
* @version $Id$
*/
final class OpDiscoverer {
/**
* The identity of the helper.
*/
private final transient Identity identity;
/**
* Public ctor.
* @param idnt The identity of helper
*/
public OpDiscoverer(final Identity idnt) {
this.identity = idnt;
}
/**
* Discover all targets in the JAR.
* @param url The URL with sources
* @return Associative array of discovered targets/operations
*/
public ConcurrentMap discover(final URL url) {
Reflections reflections;
if ("file".equals(url.getProtocol())) {
reflections = this.fromPackage(url.getPath());
} else {
throw new IllegalArgumentException(
String.format(
"Unknown protocol '%s' in '%s' (has to be 'file')",
url.getProtocol(),
url
)
);
}
return this.retrieve(reflections);
}
/**
* Discover all methods in the provided farm.
* @param farm The object annotated with {@link Farm}
* @return Associative array of discovered targets/operations
*/
private ConcurrentMap inFarm(final Object farm) {
final ConcurrentMap targets =
new ConcurrentHashMap();
for (Method method : farm.getClass().getDeclaredMethods()) {
final Annotation atn = method.getAnnotation(Operation.class);
if (atn == null) {
continue;
}
final String mnemo = ((Operation) atn).value();
targets.put(mnemo, HelpTarget.build(farm, method));
Logger.debug(
this,
"#inFarm(%s): @Operation('%[type]s') found",
farm,
mnemo
);
}
return targets;
}
/**
* Load them from reflections.
* @param ref The reflections
* @return Associative array of discovered targets/operations
*/
@SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
private ConcurrentMap retrieve(final Reflections ref) {
final ConcurrentMap targets =
new ConcurrentHashMap();
for (Class tfarm : ref.getTypesAnnotatedWith(Farm.class)) {
Logger.debug(
this,
"#discover(..): @Farm found at '%s'",
tfarm.getName()
);
Object farm;
try {
farm = tfarm.newInstance();
} catch (InstantiationException ex) {
throw new IllegalArgumentException(ex);
} catch (IllegalAccessException ex) {
throw new IllegalArgumentException(ex);
}
if (farm instanceof IdentityAware) {
final Identity safe = new SafeIdentity(this.identity);
((IdentityAware) farm).init(safe);
Logger.debug(
this,
// @checkstyle LineLength (1 line)
"#retrieve(..): %[type]s farm instantiated and initialized as '%s'",
farm,
safe
);
} else {
Logger.debug(
this,
"#retrieve(..): %[type]s farm instantiated anonymously",
farm
);
}
for (ConcurrentMap.Entry entry
: this.inFarm(farm).entrySet()) {
if (targets.containsKey(entry.getKey())) {
throw new IllegalStateException(
String.format(
// @checkstyle LineLength (1 line)
"duplicate operation '%s' in '%s' (already exists in '%s')",
entry.getKey(),
entry.getValue(),
targets.get(entry.getKey())
)
);
}
targets.put(entry.getKey(), entry.getValue());
}
}
return targets;
}
/**
* Creates reflections from package.
* @param pkg The name of the package
* @return Reflections
*/
private Reflections fromPackage(final String pkg) {
if (pkg.isEmpty()) {
throw new IllegalArgumentException(
"Package is empty, can't load classes"
);
}
String name = pkg;
if (name.charAt(0) == '/') {
name = name.substring(1);
}
return new Reflections(name);
}
}