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| import java.nio.charset.Charset;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
<!-- more -->
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReentrantLock;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hashing;
public class RandomService {
private ReentrantLock lock = new ReentrantLock();
private AtomicLong resetCounter = new AtomicLong(0);
private HashFunction sha1 = Hashing.sha1();
private int resetThreshold = 10000;
private Charset encoding = Charset.forName("UTF-8");
private SecureRandom random;
public RandomService(){
this.resetSecureRandom();
}
private void resetSecureRandom() {
this.lock.lock();
try {
this.random = SecureRandom.getInstance("NativePRNGNonBlocking");
this.random.generateSeed(32);
} catch (NoSuchAlgorithmException e) {
} finally {
this.lock.unlock();
}
}
public String getToken() {
if (this.resetCounter.incrementAndGet() > this.resetThreshold) {
this.resetSecureRandom();
this.resetCounter.set(0);
}
byte[] bytes = new byte[32];
this.random.nextBytes(bytes);
byte[] seedBytes = UUID.randomUUID().toString().getBytes(this.encoding);
byte[] seeds = new byte[seedBytes.length + bytes.length];
System.arraycopy(bytes, 0, seeds, 0, bytes.length);
System.arraycopy(seedBytes, 0, seeds, bytes.length - 1, seedBytes.length);
return this.sha1.hashBytes(bytes).toString();
}
public static void main(String[] args) {
RandomService randomService = new RandomService();
List<String> list = new ArrayList<String>(200000);
List<String> repetition = new ArrayList<String>();
for (int i = 0; i < 200000; i++) {
String t = randomService.getToken();
if (list.contains(t)) {
repetition.add(t);
} else {
list.add(t);
}
System.out.println(t);
System.out.println("i=" + i + ", 重复列表" + repetition + ",list size=" + list.size());
}
}
}
|
