字母数字序列生成器

Question

如何像
Rxt-AA0001
Rxt-AA0002
Rxt-AA0003
...
...
Rxt-AA9999
Rxt-AB0001
Rxt-AB0002

用这个

public class UserIdGenerator extends SequenceStyleGenerator {
 
    public static final String VALUE_PREFIX_PARAMETER = "valuePrefix";
    public static final String VALUE_PREFIX_DEFAULT = "";
    private String valuePrefix;
 
    public static final String NUMBER_FORMAT_PARAMETER = "numberFormat";
    public static final String NUMBER_FORMAT_DEFAULT = "%d";
    private String numberFormat;
 
    @Override
    public Serializable generate(SharedSessionContractImplementor session,
            Object object) throws HibernateException {
        return valuePrefix + String.format(numberFormat, super.generate(session, object));
    }
 
    @Override
    public void configure(Type type, Properties params,
            ServiceRegistry serviceRegistry) throws MappingException {
        super.configure(LongType.INSTANCE, params, serviceRegistry);
        valuePrefix = ConfigurationHelper.getString(VALUE_PREFIX_PARAMETER,
                params, VALUE_PREFIX_DEFAULT);
        numberFormat = ConfigurationHelper.getString(NUMBER_FORMAT_PARAMETER,
                params, NUMBER_FORMAT_DEFAULT);
    }
 
}

这是我在模型中的用户id

    @Id
    @GeneratedValue(generator = "user_seq_generator", strategy = GenerationType.SEQUENCE)
    @GenericGenerator(name = "user_seq_generator", strategy = "user.util.UserIdGenerator", parameters = {
            @Parameter(name = UserIdGenerator.INCREMENT_PARAM, value = "1"),
            @Parameter(name = UserIdGenerator.VALUE_PREFIX_PARAMETER, value = "RxT-AA"),
            @Parameter(name = UserIdGenerator.NUMBER_FORMAT_PARAMETER, value = "%04d") })
    @Column(name = "user_id")
    private String Id;

我能够生成Alpha数字id，但我不确定如何增加字符

Answer 1

它可以很简单地完成——参见下面的课程。

然而，根据目的，使用UUID可能更有益，如@某人所建议的

import java.util.Arrays;

public class AlphaNumber {
    public static char[] ALPHA_NUMBER_CHARS = "0123ABC".toCharArray(); // add here your characters
    private int[] number = new int[32]; // here you control the maximum size of the number
    private int size = 0; // here we control the actual size of the number

    public AlphaNumber() {
        Arrays.fill(number,0);
    }

    public String inc() {
        for(int i=0;i<=size;i++) {
            number[i]++;
            if (number[i] < ALPHA_NUMBER_CHARS.length) {
                break;
            }
            number[i]=0;
            size = Math.max(i+1,size);
        }
        return toString();
    }

    public String toString() {
        StringBuilder r = new StringBuilder();
        for (int i = size; i>=0; i--) {
            r.append(ALPHA_NUMBER_CHARS[number[i]]);
        }
        return new String(r);
    }

    public static void main(String[] args) {
        AlphaNumber a = new AlphaNumber();
        for (int i = 0; i < 100; i++) {
            System.out.println(a.inc());
        }
    }
}

Answer 2

通常在创建ID时，最好不要增加ID。这使他们不安全。此视频包含一个很好的解释：https://www.youtube.com/watch?v=gocwRvLhDf8

Java有一个用于生成ID的内置UUID类。这是它的javadoc：https://docs.oracle.com/javase/7/docs/api/java/util/UUID.html