com.maxifier.mxcache.impl.CustomStorageFactory Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2014 Maxifier Ltd. All Rights Reserved.
*/
package com.maxifier.mxcache.impl;
import com.maxifier.mxcache.context.CacheContext;
import com.maxifier.mxcache.provider.CacheDescriptor;
import com.maxifier.mxcache.provider.StorageFactory;
import com.maxifier.mxcache.storage.Storage;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
/**
* @author Alexander Kochurov ([email protected])
*/
public class CustomStorageFactory implements StorageFactory {
private static final Object[] EMPTY_ARRAY = {};
private final Constructor constructor;
private final Object[] arguments;
public CustomStorageFactory(CacheContext context, CacheDescriptor descriptor, Class storageClass) {
if (!Storage.class.isAssignableFrom(storageClass)) {
throw new IllegalStateException("Storage implementation should extend Storage interface " + storageClass);
}
this.constructor = getCustomConstructor(storageClass);
if (constructor == null) {
throw new IllegalStateException("Storage should have constructor taking CacheDescriptor, CacheContext or both: " + storageClass);
}
this.arguments = createArguments(constructor, context, descriptor);
}
private static boolean isAllowedConstructorArgumentType(Class type) {
return type == CacheDescriptor.class || type == CacheContext.class;
}
private static boolean isAllowedConstructorArgumentTypes(Class[] types) {
for (Class type : types) {
if (!isAllowedConstructorArgumentType(type)) {
return false;
}
}
return true;
}
@Nonnull
@Override
public Storage createStorage(Object owner) throws InvocationTargetException, IllegalAccessException, InstantiationException {
return constructor.newInstance(arguments);
}
@Override
public String getImplementationDetails() {
return constructor.getDeclaringClass().getCanonicalName();
}
@Nullable
static Constructor getCustomConstructor(Class cls) {
Constructor[] constructors = cls.getDeclaredConstructors();
Constructor res = null;
int n = 0;
for (Constructor constructor : constructors) {
Class[] types = constructor.getParameterTypes();
if (isAllowedConstructorArgumentTypes(types) && (res == null || n < types.length)) {
//noinspection unchecked
res = constructor;
n = types.length;
}
}
return res;
}
static Object[] createArguments(Constructor constructor, CacheContext context, CacheDescriptor descriptor) {
Class[] types = constructor.getParameterTypes();
if (types.length == 0) {
return EMPTY_ARRAY;
}
Object[] res = new Object[types.length];
for (int i = 0; i < types.length; i++) {
assert isAllowedConstructorArgumentType(types[i]);
res[i] = types[i] == CacheDescriptor.class ? descriptor : context;
}
return res;
}
}