VERSION 1.0 引自： http://www.coderanch.com/t/134491/Security/generating-secure-tokens
package demo;
import java.util.Random; /* * This code is a discussion of an opinion in a technical forum. * You may develope ideas from this code. You may not use it directly. */ public class DM { String getRandomIdentifier( int length) throws Exception { final int limitingValue = 64 ; // Whatever you decide, not me. if (length < limitingValue) { try { // The first step is to get a filename generator char lowerBound = 'a' ; char upperBound = 'z' ; Random randomCharacterGenerator = new Random(); // Then get some characters char [] identifierBuffer = new char [length]; // int index = identifierBuffer.length; // final int numericLowerBound = ( int ) lowerBound; final int numericUpperBound = ( int ) upperBound; final int range = numericUpperBound - numericLowerBound; // do { // recoded in mesage edit, original defective int getOne = randomCharacterGenerator.nextInt(range); int next = numericLowerBound + getOne; identifierBuffer[--index] = ( char ) next; } while (index > 0x00000000 ); return new String(identifierBuffer); // } catch (ArrayIndexOutOfBoundsException aioobe) { System.out.println(aioobe.getMessage()); } } else { throw new Exception( "Contact system administrator." ); // } return null ; } }
VERSION 2.0 改进型：
package token;
import java.util.Random;public class DM { public static void main(String[] args) throws Exception { System.out.println("1==97===:" + (int) 'a'); System.out.println("2==122===:" + (int) 'z'); System.out.println("3==65===:" + (int) 'A'); System.out.println("4===90==:" + (int) 'Z'); DM mn = new DM(); System.out.println(mn.getRandomIdentifier(26)); } String getRandomIdentifier(int length) throws Exception { final int limitingValue = 164;// Whatever you decide, not me. if (length < limitingValue) { try { // 26个小写+26个大小 = 52 字母 final int range = 52;// char[] charStr = new char[range]; int j = 0; // A=65, z =122 for (int i = 65; i <= 122; i++) { // Z--a 之间的跳过 if (i > 90 && i < 97) { continue; } charStr[j] = (char) i; // 这里将保存52个大小字母 j++; }// 这里其实可以将 0 - 9 的数字也添加进去
Random randomCharacterGenerator = new Random(); // Then get some characters char[] identifierBuffer = new char[length];// int index = identifierBuffer.length;// do { // 产生0至51 共52个随机数，用于索引字母数组 int getOne = randomCharacterGenerator.nextInt(range); identifierBuffer[--index] = charStr[getOne]; } while (index > 0x00000000); return new String(identifierBuffer);// } catch (ArrayIndexOutOfBoundsException aioobe) { System.out.println(aioobe.getMessage()); } } else { throw new Exception("Contact system administrator.");// } return null; }}