12唯一订单号生成 方法总结

1:  时间戳是当前时间到1970年的毫秒数。
你非要12位可以 :
new Date().getTime()-1300000000000L
这个数至少100年还是12位。而且不会重复



时间戳高并发还是会有重复的，你应该每获取一次加1的方法生成。用锁对象或者把方法声明为synchronized保证并发也不会重复。如果有用数据库，也可以用数据库提供的sequence来帮你生成

抽取一个方法

这种一般都是序号吧 或者一段字符加上序号 每次取得时候加一

java应该用UUID.
或者数据库上SEQ实现



Calendar calendar = Calendar.getInstance();
System.out.println("现在："+calendar.getTime().getTime());
calendar.add(Calendar.YEAR, 10);
System.out.println("10年后："+calendar.getTime().getTime());

输出：

现在：1404208483914

10年后：1719827683914

如果用时间戳，截取后面12位，不要第一位，18年内都不会有大问题，不过这样的话，你的生成ID的方法就得同步，避免高并发的时候可能出现的相同ID（理论上很有可能的，虽然1毫秒内出现生成多个订单的几率很小）





package com.tangkuo.utils;

import java.util.Date;
import java.util.UUID;

public class TestNums {
public static void main(String[] args) {
long time = new Date().getTime()-1300000000000L;
System.out.println("=" + time);

System.out.println("System.currentTimeMillis()1 = " + System.currentTimeMillis());
System.out.println("UUID.randomUUID() = " + UUID.randomUUID());
System.out.println("System.currentTimeMillis()2 = " + System.currentTimeMillis());

}

}




package com.iec.app.utils;


import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class RandomId {
    private Random random;
    private String table;
    private static final int radLength =15;
    private static final String[] radArr = new String[]{"A","B","C","D","E","F","G","H","I","G","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
   
   
    public RandomId() {
        random = new Random();
        table = "0123456789";
    }
    public String randomId(long id) {
        String ret = null,num = String.format("%05d", id);
        int key = random.nextInt(10),seed = random.nextInt(100);
        Caesar caesar = new Caesar(table, seed);
        num = caesar.encode(key, num);
        ret = num  + String.format("%01d", key)  + String.format("%02d", seed);
       
        // 加入生成的随机字符
       /* int letterSize = radLength - ret.length();
        for(int i=0;i<letterSize;i++){
        String letter = radArr[ random.nextInt(radArr.length)];
        int index = random.nextInt(ret.length());
        ret = ret.substring(0, index) + letter + ret.substring(index, ret.length());
        }*/
       
        return ret;
    }
   
   
    public static void main(String[] args) {
        RandomId r = new RandomId();
        System.out.println(r.randomId(12));
    }
}



package com.iec.app.utils;


/**
*
* @author
*
*/
public class Caesar {
    private String table;
    private int seedA = 1103515245;
    private int seedB = 12345;
   
    public Caesar(String table, int seed) {
        this.table = chaos(table, seed, table.length());
    }
    public Caesar(String table) {
        this(table, 11);
    }
    public Caesar() {
        this(11);
    }
    public Caesar(int seed) {
        this("ABCDEFGHIJKLMNOPQRSTUVWXYZ", seed);
    }
    public char dict(int i, boolean reverse) {
        int s = table.length(), index = reverse ? s - i : i;
        return table.charAt(index);
    }
    public int dict(char c,  boolean reverse) {
        int s = table.length(), index = table.indexOf(c);
        return reverse ? s - index : index;
    }
    public int seed(int seed) {
        long temp = seed;
        return (int)((temp * seedA + seedB) & 0x7fffffffL);
    }

    public String chaos(String data, int seed, int cnt) {
        StringBuffer buf = new StringBuffer(data);
        char tmp; int a, b, r = data.length();
        for (int i = 0; i < cnt; i += 1) {
            seed = seed(seed); a = seed % r;
            seed = seed(seed); b = seed % r;
            tmp = buf.charAt(a);
            buf.setCharAt(a, buf.charAt(b));
            buf.setCharAt(b, tmp);
        }
        return buf.toString();
    }

    public String crypto(boolean reverse,
                         int key, String text) {
        String ret = null;
        StringBuilder buf = new StringBuilder();
        int m, s = table.length(), e = text.length();

        for(int i = 0; i < e; i += 1) {
            m = dict(text.charAt(i), reverse);
            if (m < 0) break;
            m = m + key + i;
            buf.append(dict(m % s, reverse));
        }
        if (buf.length() == e)
            ret = buf.toString();
        return ret;
    }
    public String encode(int key, String text) {
        return crypto(false, key, text);
       
    }
    public String decode(int key, String text) {
        return crypto(true , key, text);
    }
   
    public static void main(String[] args) {
        Caesar caesar = new Caesar();
        String data = caesar.encode(32, "APPLE");
        caesar.decode(32, data);
    }
}