史上最全的java随机数生成算法分享

复制代码 代码如下:
String password = RandomUtil.generateString(10);

源码如下：

复制代码 代码如下:
package com.javaniu.core.util;
import java.util.Random;
public class RandomUtil {
 public static final String ALLCHAR = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 public static final String LETTERCHAR = "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 public static final String NUMBERCHAR = "0123456789";

 
 public static String generateString(int length) {
  StringBuffer sb = new StringBuffer();
  Random random = new Random();
  for (int i = 0; i < length; i++) {
   sb.append(ALLCHAR.charAt(random.nextInt(ALLCHAR.length())));
  }
  return sb.toString();
 }

 
 public static String generateMixString(int length) {
  StringBuffer sb = new StringBuffer();
  Random random = new Random();
  for (int i = 0; i < length; i++) {
   sb.append(ALLCHAR.charAt(random.nextInt(LETTERCHAR.length())));
  }
  return sb.toString();
 }

 
 public static String generateLowerString(int length) {
  return generateMixString(length).toLowerCase();
 }

 
 public static String generateUpperString(int length) {
  return generateMixString(length).toUpperCase();
 }

 
 public static String generateZeroString(int length) {
  StringBuffer sb = new StringBuffer();
  for (int i = 0; i < length; i++) {
   sb.append('0');
  }
  return sb.toString();
 }

 
 public static String toFixdLengthString(long num, int fixdlenth) {
  StringBuffer sb = new StringBuffer();
  String strNum = String.valueOf(num);
  if (fixdlenth - strNum.length() >= 0) {
   sb.append(generateZeroString(fixdlenth - strNum.length()));
  } else {
   throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth
     + "的字符串发生异常！");
  }
  sb.append(strNum);
  return sb.toString();
 }

 
 public static int getNotSimple(int[] param, int len) {
  Random rand = new Random();
  for (int i = param.length; i > 1; i--) {
   int index = rand.nextInt(i);
   int tmp = param[index];
   param[index] = param[i - 1];
   param[i - 1] = tmp;
  }
  int result = 0;
  for (int i = 0; i < len; i++) {
   result = result * 10 + param[i];
  }
  return result;
 }

 public static void main(String[] args) {
  System.out.println("返回一个定长的随机字符串(只包含大小写字母、数字):" + generateString(10));
  System.out
    .println("返回一个定长的随机纯字母字符串(只包含大小写字母):" + generateMixString(10));
  System.out.println("返回一个定长的随机纯大写字母字符串(只包含大小写字母):"
    + generateLowerString(10));
  System.out.println("返回一个定长的随机纯小写字母字符串(只包含大小写字母):"
    + generateUpperString(10));
  System.out.println("生成一个定长的纯0字符串:" + generateZeroString(10));
  System.out.println("根据数字生成一个定长的字符串，长度不够前面补0:"
    + toFixdLengthString(123, 10));
  int[] in = { 1, 2, 3, 4, 5, 6, 7 };
  System.out.println("每次生成的len位数都不相同:" + getNotSimple(in, 3));
 }
}

有图有真相：

java随机字符补充版

今天在zuidaimai看到一个java随机字符生成demo，正好要用，但发现不完整，重新整理一下，分享给有需要的朋友

复制代码 代码如下:
public static void main(String[] args) {   
        //String s = RandomNum.getRandomNumStr(5);
        //System.out.println(s);
        System.out.println("生成5个含有5个字符的字符串：");
        RandomNum.SuiJiZiFuChuan(5,5);
        System.out.println("生成3个含有6个字符的字符串：");
        RandomNum.SuiJiZiFuChuan(6,3);
        System.out.println("生成任意1到20个含有任意1到10个字符的字符串：");
        RandomNum.SuiJiZiFuChuan((int)(20*Math.random()),(int)(10*Math.random()));
        System.out.println("随机性生成字符：");
        int i=0;
        while(i<(int)(10*Math.random())){
            RandomNum.SuiJiZiFuChuan((int)(20*Math.random()),1);
            i++;
        }
    }   

    public static void SuiJiZiFuChuan(int x,int y){
        for(int j=0;j            for(int i=0;i                int a=(int)(100*Math.random()+100*Math.random());
                while(true){
                    if(a>96&a<123)
                        break;
                    else
                        a=(int)(100*Math.random()+100*Math.random());
                }
                System.out.print((char)a);
            }
            System.out.println();
        }
    }

执行结果：来源： http://www.zuidaima.com/share/1585762703215616.htm