package com.springmvc.domain;
...

➊

import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
import javax.validation.constraints.Min;
import javax.validation.constraints.Digits;
import javax.validation.constraints.NotNull;

public class Book {
    @Pattern(regexp="ISBN[1-9]+") ➋
    private String bookId;

    @Size(min=4, max=50) ➌
    private String name;

    @Min(value=0) ➍
    @Digits(integer=8, fraction=2) ➎
    @NotNull ➏
    private int unitPrice;
    ...
}