/**
* Copyright 2010 Google Inc.
*
* 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.waveprotocol.wave.model.id;
import org.waveprotocol.wave.model.util.CharBase64;
import org.waveprotocol.wave.model.util.Preconditions;
import java.util.Random;
/**
* A {@link TokenGenerator} that uses a {@link Random} to generate tokens.
*
* @author ljvderijk@google.com (Lennard de Rijk)
*/
public class TokenGeneratorImpl implements TokenGenerator {
private final Random random;
public TokenGeneratorImpl(Random random) {
this.random = random;
}
public String generateToken(int length) {
Preconditions.checkArgument(length > 0, "Requested length must be larger then 0");
// Every 4 characters is represented by 3 bytes, therefore rounding up to
// a multiple of 3.
int numBytes = (int) Math.ceil(length / 4.0) * 3;
byte[] bytes = new byte[numBytes];
random.nextBytes(bytes);
String token = CharBase64.encodeWebSafe(bytes, false);
return token.substring(0, length);
}
}