如何根据一个串产生唯一的序列？

[kyousuke]

比如给一个字符串"12345678"，然后基于这个串产生一个N长度的唯一串，其实就是12345678为种子。
类似UUID，但是UUID好像长度一定是16位的？我想能够产生指定长度的唯一串。

[花谢尊前不敢香]

加密吧

[lost_guy_in_scut]

找一个好点的哈希函数呗。MurmurHash似乎可以满足楼主需求。

[keithcai]

md5嘛

[孤雨]

md5或是其他的 java都有实现 直接调用即可

[a512796048]

des 加密 楼主自己研究

package p;  
import java.security.Key;    
import java.security.SecureRandom;    
   
import javax.crypto.Cipher;    
import javax.crypto.KeyGenerator;    
   
import sun.misc.BASE64Decoder;    
import sun.misc.BASE64Encoder;    
   
public class DES {    
       
  Key key;    
   
  public DES(String str) {    
    setKey(str);//生成密匙    
  }    
   
  public DES() {    
    setKey(“siyue_qi”);    
  }    
   
  /**   
   * 根据参数生成KEY   
   */   
  public void setKey(String strKey) {    
      try {    
        KeyGenerator _generator = KeyGenerator.getInstance(“DES”);    
        _generator.init(new SecureRandom(strKey.getBytes()));    
        this.key = _generator.generateKey();    
        _generator = null;    
      } catch (Exception e) {    
        throw new RuntimeException(    
           “Error initializing SqlMap class. Cause:” + e);    
      }    
  }    
   
  /**   
   * 加密String明文输入,String密文输出   
   */   
  public String getEncString(String strMing) {    
      byte[] byteMi = null;    
      byte[] byteMing = null;    
      String strMi =““;    
      BASE64Encoder base64en = new BASE64Encoder();    
      try {    
        byteMing = strMing.getBytes(“UTF8”);    
        byteMi = this.getEncCode(byteMing);    
        strMi = base64en.encode(byteMi);    
      } catch (Exception e) {    
        throw new RuntimeException(    
           “Error initializing SqlMap class. Cause:” + e);    
      } finally {    
        base64en = null;    
        byteMing = null;    
        byteMi = null;    
      }    
      return strMi;    
  }    
   
  /**   
   * 解密 以String密文输入,String明文输出   
   * @param strMi   
   * @return   
   */   
  public String getDesString(String strMi) {    
      BASE64Decoder base64De = new BASE64Decoder();    
      byte[] byteMing = null;    
      byte[] byteMi = null;    
      String strMing =““;    
      try {    
        byteMi = base64De.decodeBuffer(strMi);    
        byteMing = this.getDesCode(byteMi);    
        strMing = new String(byteMing,”UTF8”);    
      } catch (Exception e) {    
        throw new RuntimeException(    
          “Error initializing SqlMap class. Cause:” + e);    
      } finally {    
        base64De = null;    
        byteMing = null;    
        byteMi = null;    
      }    
      return strMing;    
  }    
   
  /**   
   * 加密以byte[]明文输入,byte[]密文输出   
   * @param byteS   
   * @return   
   */   
  private byte[] getEncCode(byte[] byteS) {    
      byte[] byteFina = null;    
      Cipher cipher;    
      try {    
        cipher = Cipher.getInstance(“DES”);    
        cipher.init(Cipher.ENCRYPT_MODE, key);    
        byteFina = cipher.doFinal(byteS);    
      } catch (Exception e) {    
        throw new RuntimeException(    
          “Error initializing SqlMap class. Cause:” + e);    
      } finally {    
        cipher = null;    
      }    
      return byteFina;    
  }    
   
  /**   
   * 解密以byte[]密文输入,以byte[]明文输出   
   * @param byteD   
   * @return   
   */   
  private byte[] getDesCode(byte[] byteD) {    
      Cipher cipher;    
      byte[] byteFina = null;    
      try {    
        cipher = Cipher.getInstance(“DES”);    
        cipher.init(Cipher.DECRYPT_MODE, key);    
        byteFina = cipher.doFinal(byteD);    
      } catch (Exception e) {    
        throw new RuntimeException(    
          “Error initializing SqlMap class. Cause:” + e);    
      } finally {    
        cipher = null;    
      }    
      return byteFina;    
  }    
   
  public static void main(String args[]) {    
      DES des = new DES();    
      // 设置密钥    
      //des.setKey(“12345678”);    
   
      String str1 =“密文”;    
      //DES加密    
      String str2 = des.getEncString(str1);    
      String deStr = des.getDesString(str2);    
      System.out.println(“密文:”str2);    
      //DES解密    
      System.out.println(“明文:”deStr);    
  }   

[flowerjack]

UUID