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Java 1.8+ Library with tons of utility classes required in all projects
/*
* Copyright (C) 2014-2022 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* 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.helger.commons.lang;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.PresentForCodeCoverage;
import com.helger.commons.collection.ArrayHelper;
/**
* This is a special helper class that provides many utility methods concerning
* the usage of reflection etc..
*
* @author Philip Helger
*/
@Immutable
public final class GenericReflection
{
private static final Logger LOGGER = LoggerFactory.getLogger (GenericReflection.class);
private static final Class [] EMPTY_CLASS_ARRAY = new Class [0];
@PresentForCodeCoverage
private static final GenericReflection INSTANCE = new GenericReflection ();
private GenericReflection ()
{}
@SuppressWarnings ("unchecked")
public static DSTTYPE uncheckedCast (@Nullable final SRCTYPE aObject)
{
return (DSTTYPE) aObject;
}
@Nonnull
public static Class getClassFromName (@Nonnull final ClassLoader aClassLoader,
@Nonnull final String sName) throws ClassNotFoundException
{
ValueEnforcer.notNull (aClassLoader, "ClassLoader");
return uncheckedCast (aClassLoader.loadClass (sName));
}
@Nonnull
public static Class getClassFromName (@Nonnull final String sName) throws ClassNotFoundException
{
return uncheckedCast (Class.forName (sName));
}
/**
* Get the class of the given name
*
* @param
* The return type
* @param aClassLoader
* The class loader to be used. May not be null.
* @param sName
* The name to be resolved.
* @return null if the class could not be resolved
*/
@Nullable
public static Class getClassFromNameSafe (@Nonnull final ClassLoader aClassLoader, @Nonnull final String sName)
{
ValueEnforcer.notNull (aClassLoader, "ClassLoader");
try
{
return getClassFromName (aClassLoader, sName);
}
catch (final ClassNotFoundException e)
{
return null;
}
}
/**
* Get the class of the given name
*
* @param
* The return type
* @param sName
* The name to be resolved.
* @return null if the class could not be resolved
*/
@Nullable
public static Class getClassFromNameSafe (@Nonnull final String sName)
{
try
{
return getClassFromName (sName);
}
catch (final ClassNotFoundException e)
{
return null;
}
}
/**
* Get an array with all the classes of the passed object array.
*
* @param aObjs
* The object array. May be null. No contained element may
* be null.
* @return A non-null array of classes.
*/
@Nonnull
public static Class [] getClassArray (@Nullable final Object... aObjs)
{
if (ArrayHelper.isEmpty (aObjs))
return EMPTY_CLASS_ARRAY;
final Class [] ret = new Class [aObjs.length];
for (int i = 0; i < aObjs.length; ++i)
ret[i] = aObjs[i].getClass ();
return ret;
}
/**
* This method dynamically invokes the method with the given name on the given
* object.
*
* @param
* The method return type
* @param aSrcObj
* The source object on which the method is to be invoked. May not be
* null.
* @param sMethodName
* The method to be invoked.
* @param aArgs
* The arguments to be passed into the method. May be null
* . If not null, the members of the array may not be
* null because otherwise the classes of the arguments
* cannot be determined and will throw an Exception!
* @return The return value of the invoked method or null for
* void methods.
* @throws NoSuchMethodException
* Thrown by reflection
* @throws IllegalAccessException
* Thrown by reflection
* @throws InvocationTargetException
* Thrown by reflection
*/
@Nullable
public static RETURNTYPE invokeMethod (@Nonnull final Object aSrcObj,
@Nonnull final String sMethodName,
@Nullable final Object... aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException
{
return GenericReflection. invokeMethod (aSrcObj, sMethodName, getClassArray (aArgs), aArgs);
}
@Nullable
public static RETURNTYPE invokeMethod (@Nonnull final Object aSrcObj,
@Nonnull final String sMethodName,
@Nullable final Class [] aArgClasses,
@Nullable final Object [] aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException
{
final Method aMethod = aSrcObj.getClass ().getDeclaredMethod (sMethodName, aArgClasses);
final Object aReturn = aMethod.invoke (aSrcObj, aArgs);
return GenericReflection.uncheckedCast (aReturn);
}
@Nullable
public static RETURNTYPE invokeStaticMethod (@Nonnull final String sClassName,
@Nonnull final String sMethodName,
@Nullable final Object... aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException,
ClassNotFoundException
{
return GenericReflection. invokeStaticMethod (getClassFromName (sClassName), sMethodName, aArgs);
}
@Nullable
public static RETURNTYPE invokeStaticMethod (@Nonnull final Class aClass,
@Nonnull final String sMethodName,
@Nullable final Object... aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException
{
return GenericReflection. invokeStaticMethod (aClass, sMethodName, getClassArray (aArgs), aArgs);
}
@Nullable
public static RETURNTYPE invokeStaticMethod (@Nonnull final String sClassName,
@Nonnull final String sMethodName,
@Nullable final Class [] aArgClasses,
@Nullable final Object [] aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException,
ClassNotFoundException
{
return GenericReflection. invokeStaticMethod (getClassFromName (sClassName), sMethodName, aArgClasses, aArgs);
}
@Nullable
public static RETURNTYPE invokeStaticMethod (@Nonnull final Class aClass,
@Nonnull final String sMethodName,
@Nullable final Class [] aArgClasses,
@Nullable final Object [] aArgs) throws NoSuchMethodException,
IllegalAccessException,
InvocationTargetException
{
final Method aMethod = aClass.getDeclaredMethod (sMethodName, aArgClasses);
final Object aReturn = aMethod.invoke (null, aArgs);
return GenericReflection.uncheckedCast (aReturn);
}
@Nonnull
public static Constructor findConstructor (@Nonnull final DATATYPE aObj,
final Class ... aCtorArgs) throws NoSuchMethodException
{
return uncheckedCast (aObj.getClass ().getConstructor (aCtorArgs));
}
/**
* Create a new instance of the class identified by the passed object. The
* default constructor will be invoked.
*
* @param
* The type of object to be created.
* @param aObj
* The object from which the class should be used.
* @return A new instance of the object or an exception is thrown.
* @throws IllegalAccessException
* Reflection exception
* @throws NoSuchMethodException
* Reflection exception
* @throws InvocationTargetException
* Reflection exception
* @throws InstantiationException
* Reflection exception
*/
@Nonnull
public static DATATYPE newInstance (@Nonnull final DATATYPE aObj) throws IllegalAccessException,
NoSuchMethodException,
InvocationTargetException,
InstantiationException
{
return findConstructor (aObj).newInstance ();
}
@Nullable
public static DATATYPE newInstance (@Nullable final Class aClass)
{
if (aClass != null)
try
{
return aClass.getDeclaredConstructor ().newInstance ();
}
catch (final Exception ex)
{
/*
* Catch all exceptions because any exception thrown from the
* constructor may also end up in this catch block
*/
LOGGER.error ("Failed to instantiate " + aClass, ex);
}
return null;
}
@Nullable
public static DATATYPE newInstance (@Nonnull final ClassLoader aClassLoader,
@Nullable final String sClassName,
@Nullable final Class aDesiredType)
{
if (sClassName != null && aDesiredType != null)
try
{
return aDesiredType.cast (getClassFromName (aClassLoader, sClassName).getDeclaredConstructor ().newInstance ());
}
catch (final Exception ex)
{
/*
* Catch all exceptions because any exception thrown from the
* constructor (indirectly invoked by newInstance) may also end up in
* this catch block
*/
LOGGER.error ("Failed to instantiate '" + sClassName + "'", ex);
}
return null;
}
@Nullable
public static DATATYPE newInstance (@Nullable final String sClassName, @Nullable final Class aDesiredType)
{
if (sClassName != null && aDesiredType != null)
try
{
return aDesiredType.cast (getClassFromName (sClassName).getDeclaredConstructor ().newInstance ());
}
catch (final Exception ex)
{
/*
* Catch all exceptions because any exception thrown from the
* constructor (indirectly invoked by newInstance) may also end up in
* this catch block
*/
LOGGER.error ("Failed to instantiate '" + sClassName + "'", ex);
}
return null;
}
@Nullable
public static DATATYPE newInstance (@Nullable final String sClassName,
@Nullable final Class aDesiredType,
@Nullable final ClassLoader aClassLoaderToUse)
{
if (sClassName != null && aDesiredType != null && aClassLoaderToUse != null)
try
{
return aDesiredType.cast (Class.forName (sClassName, true, aClassLoaderToUse).getDeclaredConstructor ().newInstance ());
}
catch (final Exception ex)
{
/*
* Catch all exceptions because any exception thrown from the
* constructor (indirectly invoked by newInstance) may also end up in
* this catch block
*/
LOGGER.error ("Failed to instantiate '" + sClassName + "' with CL " + aClassLoaderToUse, ex);
}
return null;
}
}