基于文件的图书管理系统二：实体类+工具类

实体类

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder
@ToString
public class Book {
    private String isbn;
    private String name;
    private String auth;
    private LocalDate birth;
    private String publisher;
    private BigDecimal price;
}

全局常量接口

public interface BMS {
    String DB_BOOKS = "db_books";
}

全局自定义异常类

public class GlobalException extends RuntimeException {

    public GlobalException() {
        super();
    }

    public GlobalException(String message) {
        super(message);
    }

}

随机数工具类

参考博客：随机工具类

字符串工具类

public class StringUtil {
    /**
     * 当字符串为null或长度等于0时，返回true
     *
     * @param cs
     * @return
     */
    public static boolean isEmpty(CharSequence cs) {
        return cs == null || cs.length() == 0;
    }

    /**
     * 判断字符串是否为空字符串，全部空白字符也为空。
     *
     * @param cs
     * @return
     */
    public static boolean isBlank(CharSequence cs) {
        int strLen;
        if (cs != null && (strLen = cs.length()) != 0) {
            for (int i = 0; i = min && price