/*
* Copyright 2014-2017 the original author or authors.
*
* 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 org.springframework.data.keyvalue.core;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicReference;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.data.util.TypeInformation;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
/**
* Default implementation of {@link IdentifierGenerator} to generate identifiers of types {@link UUID}, String,
*
* @author Christoph Strobl
* @author Oliver Gierke
*/
enum DefaultIdentifierGenerator implements IdentifierGenerator {
INSTANCE;
private final AtomicReference<SecureRandom> secureRandom = new AtomicReference<>(null);
/*
* (non-Javadoc)
* @see org.springframework.data.keyvalue.core.IdentifierGenerator#newIdForType(org.springframework.data.util.TypeInformation)
*/
@Override
@SuppressWarnings("unchecked")
public <T> T generateIdentifierOfType(TypeInformation<T> identifierType) {
Class<?> type = identifierType.getType();
if (ClassUtils.isAssignable(UUID.class, type)) {
return (T) UUID.randomUUID();
} else if (ClassUtils.isAssignable(String.class, type)) {
return (T) UUID.randomUUID().toString();
} else if (ClassUtils.isAssignable(Integer.class, type)) {
return (T) Integer.valueOf(getSecureRandom().nextInt());
} else if (ClassUtils.isAssignable(Long.class, type)) {
return (T) Long.valueOf(getSecureRandom().nextLong());
}
throw new InvalidDataAccessApiUsageException("Non gereratable id type....");
}
private SecureRandom getSecureRandom() {
SecureRandom secureRandom = this.secureRandom.get();
if (secureRandom != null) {
return secureRandom;
}
for (String algorithm : OsTools.secureRandomAlgorithmNames()) {
try {
secureRandom = SecureRandom.getInstance(algorithm);
} catch (NoSuchAlgorithmException e) {
// ignore and try next.
}
}
if (secureRandom == null) {
throw new InvalidDataAccessApiUsageException(
String.format("Could not create SecureRandom instance for one of the algorithms '%s'.",
StringUtils.collectionToCommaDelimitedString(OsTools.secureRandomAlgorithmNames())));
}
this.secureRandom.compareAndSet(null, secureRandom);
return secureRandom;
}
/**
* @author Christoph Strobl
* @since 1.1.2
*/
private static class OsTools {
private static final String OPERATING_SYSTEM_NAME = System.getProperty("os.name").toLowerCase();
private static final List<String> SECURE_RANDOM_ALGORITHMS_LINUX_OSX_SOLARIS = Arrays.asList("NativePRNGBlocking",
"NativePRNGNonBlocking", "NativePRNG", "SHA1PRNG");
private static final List<String> SECURE_RANDOM_ALGORITHMS_WINDOWS = Arrays.asList("SHA1PRNG", "Windows-PRNG");
static List<String> secureRandomAlgorithmNames() {
return OPERATING_SYSTEM_NAME.indexOf("win") >= 0 ? SECURE_RANDOM_ALGORITHMS_WINDOWS
: SECURE_RANDOM_ALGORITHMS_LINUX_OSX_SOLARIS;
}
}
}