java生成固定位数，随机数，纯数字，不重复，简单。

import java.util.Random;

public class NumberGenerator {
    public NumberGenerator() {
    }
    //随机数工具方法
    public static long getNumber(int length) {
        StringBuilder buf = new StringBuilder();
        Random random = new Random();
        int firstNumber = random.nextInt(9) + 1; //开头不为0
        buf.append(firstNumber);

        for(int i = 0; i < length - 1; ++i) {
            buf.append(random.nextInt(10));
        }

        return Long.valueOf(buf.toString());
    }
}

mybatis-plus service:

@Override
@Transactional(propagation = Propagation.REQUIRES_NEW)//脱离业务事务，开启新事务
private String getNumber(int length, int numberType) {
        String number = null;
        ResourceNumber resourceNumber = new ResourceNumber();
        //最多尝试10次
        for (int time = 0; time < 10; time++) {
            try {
                long userNumberL = NumberGenerator.getNumber(length);
                resourceNumber.setNumber(userNumberL);
         

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