blocks|key|1244608|text|创建一个UUID。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1244609|String+uniqueID+=+UUID.randomUUID().toString();|code-block|syntax|javascript|1244610|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/8/docs/api/java/util/UUID.html^0|4|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Create a <a href="http://docs.oracle.com/javase/8/docs/api/java/util/UUID.html" rel="noreferrer">UUID</a>.

<pre><code>String uniqueID = UUID.randomUUID().toString();
</code></pre>

blocks|key|1459317|text|java.util.UUID：toString()方法|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1459318|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/util/UUID.html^0|0|E|0|E|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

<a href="http://java.sun.com/javase/6/docs/api/java/util/UUID.html" rel="noreferrer"><code>java.util.UUID</code></a> : toString() method

blocks|key|1459396|text|使用Java生成唯一ID|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1459397|UUID是Java中生成唯一ID的最快、最简单的方法。|1459398|import+java.util.UUID;

public+class+UniqueIDTest+{
++public+static+void+main(String[]+args)+{
++++UUID+uniqueKey+=+UUID.randomUUID();
++++System.out.println+(uniqueKey);
++}
}|code-block|syntax|javascript|1459399|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Generate Unique ID Using Java
UUID is the fastest and easiest way to generate unique ID in Java.
<pre><code>import java.util.UUID;

public class UniqueIDTest {
 public static void main(String[] args) {
 UUID uniqueKey = UUID.randomUUID();
 System.out.println (uniqueKey);
 }
}
</code></pre>

blocks|key|1459491|text|这增加了UUID生成的随机性，但确保每个生成的id的长度相同|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1459492|import+org.apache.commons.codec.digest.DigestUtils;
import+java.util.UUID;

public+String+createSalt()+{
++++String+ts+=+String.valueOf(System.currentTimeMillis());
++++String+rand+=+UUID.randomUUID().toString();
++++return+DigestUtils.sha1Hex(ts+%2B+rand);
}|code-block|syntax|javascript|1459493|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This adds a bit more randomness to the UUID generation but ensures each generated id is the same length

<pre><code>import org.apache.commons.codec.digest.DigestUtils;
import java.util.UUID;

public String createSalt() {
 String ts = String.valueOf(System.currentTimeMillis());
 String rand = UUID.randomUUID().toString();
 return DigestUtils.sha1Hex(ts + rand);
}
</code></pre>

blocks|key|1459452|text|我们可以使用UUID在java中创建一个唯一的ID，并像UUID上的randomUUID()一样调用该方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1459453|String+uniqueID+=+UUID.randomUUID().toString();|code-block|syntax|javascript|1459454|这将生成返回类型为String的随机uniqueID。|1459455|entityMap^0|6|4|S|4|Y|C|0|0|9|6|I|8|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

We can create a unique ID in java by using the <code>UUID</code> and call the method like <code>randomUUID()</code> on <code>UUID</code>.

<pre><code>String uniqueID = UUID.randomUUID().toString();
</code></pre>

This will generate the random <code>uniqueID</code> whose return type will be <code>String</code>.

blocks|key|1244813|text|在java中有三种方法来生成唯一id。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1244814|1)+UUID类提供了一种生成唯一ids的简单方法。|1244815|+UUID+id+=+UUID.randomUUID();
+System.out.println(id);|code-block|syntax|javascript|1244816|2)+SecureRandom和MessageDigest|1244817|//initialization+of+the+application
+SecureRandom+prng+=+SecureRandom.getInstance("SHA1PRNG");

//generate+a+random+number
+String+randomNum+=+new+Integer(prng.nextInt()).toString();

//get+its+digest
+MessageDigest+sha+=+MessageDigest.getInstance("SHA-1");
+byte[]+result+=++sha.digest(randomNum.getBytes());

System.out.println("Random+number:+"+%2B+randomNum);
System.out.println("Message+digest:+"+%2B+new+String(result));|1244818|3)使用java.rmi.server.UID|1244819|UID+userId+=+new+UID();
System.out.println("userId:+"+%2B+userId);|1244820|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

There are three way to generate unique id in java.

1) the UUID class provides a simple means for generating unique ids.

<pre><code> UUID id = UUID.randomUUID();
 System.out.println(id);
</code></pre>

2) SecureRandom and MessageDigest

<pre><code>//initialization of the application
 SecureRandom prng = SecureRandom.getInstance("SHA1PRNG");

//generate a random number
 String randomNum = new Integer(prng.nextInt()).toString();

//get its digest
 MessageDigest sha = MessageDigest.getInstance("SHA-1");
 byte[] result = sha.digest(randomNum.getBytes());

System.out.println("Random number: " + randomNum);
System.out.println("Message digest: " + new String(result));
</code></pre>

3) using a java.rmi.server.UID

<pre><code>UID userId = new UID();
System.out.println("userId: " + userId);
</code></pre>

blocks|key|1244824|text|String+name,password;

public+int+idGen()+{

++++int+id+=+this.name.hashCode()+%2B+this.password.hashCode();
++++int+length+=+String.valueOf(id).length();
++++int+Max_Length+=+5;
++++if(String.valueOf(id).length()>Max_Length)+
++++{
++++++++id+=+(int)+(id+/Math.pow(10.0,length+-+Max_Length+));
++++}
++++return++id;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1244825|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>String name,password;

public int idGen() {

 int id = this.name.hashCode() + this.password.hashCode();
 int length = String.valueOf(id).length();
 int Max_Length = 5;
 if(String.valueOf(id).length()&gt;Max_Length) 
 {
 id = (int) (id /Math.pow(10.0,length - Max_Length ));
 }
 return id;
}
</code></pre>

I'm looking for the best way to create a unique ID as a String in Java.

Any guidance appreciated, thanks.

I should mention I'm using Java 5.

How do I create a unique ID in Java?

Java

我正在寻找在Java中将唯一ID创建为字符串的最佳方法。感谢您的指导，谢谢。我应该提一下我使用的是Java5。

问如何在Java中创建唯一ID？
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