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CommandUtils.java
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CommandUtils.java
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/*
* The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
* (the "License"). You may not use this work except in compliance with the License, which is
* available at www.apache.org/licenses/LICENSE-2.0
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied, as more fully set forth in the License.
*
* See the NOTICE file distributed with this work for information regarding copyright ownership.
*/
package alluxio.cli;
import alluxio.util.CommonUtils;
import com.google.common.base.Throwables;
import org.reflections.Reflections;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.concurrent.ThreadSafe;
/**
* Class for convenience methods used by instances of {@link Command}.
*/
@ThreadSafe
public final class CommandUtils {
private CommandUtils() {} // prevent instantiation
/**
* Get instances of all subclasses of {@link Command} in the given package.
*
* @param pkgName package prefix to look in
* @param classArgs type of args to instantiate the class
* @param objectArgs args to instantiate the class
* @return a mapping from command name to command instance
*/
public static Map<String, Command> loadCommands(String pkgName, Class[] classArgs,
Object[] objectArgs) {
Map<String, Command> commandsMap = new HashMap<>();
Reflections reflections = new Reflections(Command.class.getPackage().getName());
for (Class<? extends Command> cls : reflections.getSubTypesOf(Command.class)) {
if (cls.getPackage().getName().startsWith(pkgName)
&& !Modifier.isAbstract(cls.getModifiers())) {
// Only instantiate a concrete class
Command cmd;
try {
cmd = CommonUtils.createNewClassInstance(cls, classArgs, objectArgs);
} catch (Exception e) {
throw Throwables.propagate(e);
}
commandsMap.put(cmd.getCommandName(), cmd);
}
}
return commandsMap;
}
}