java如何获得与Joda DateTime后端兼容的完整HTML时区选择

Question

JodaTime DateTimeZone类提供了getAvailableIDs方法来列出Java平台提供的时区标识符。是否有一个简单的HTML select标记和选项列出兼容的时区标识符

Answer 1

生成的HTML太大，无法在此处发布，但下面的实用程序会生成所需的HTML选择和选项标记

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import org.joda.time.DateTimeZone;

public class DateTimeUtils {

  /**
   * Prevents the construction of instances of this utility class which has only static methods.
   */
  private DateTimeUtils() {
  }

  /**
   * Displays the timezone identifiers provided by the system.
   */
  public static void listAvailableIDs() {
    final Set<String> availableIDs = DateTimeZone.getAvailableIDs();
    final List<String> sortedAvailableIDs = new ArrayList<>();
    sortedAvailableIDs.addAll(availableIDs);
    Collections.sort(sortedAvailableIDs);
    for (final String sortedAvailableID : sortedAvailableIDs) {
      System.out.println(sortedAvailableID);
    }
  }

  /**
   * Generates an HTML select element for the timezone identifiers accepted by Joda DateTime on Java 15.
   */
  public static void generateHTMLTimezoneSelect() {
    final Set<String> availableIDs = DateTimeZone.getAvailableIDs();
    final List<String> sortedAvailableIDs = new ArrayList<>();
    sortedAvailableIDs.addAll(availableIDs);
    Collections.sort(sortedAvailableIDs);
    final StringBuilder stringBuilder = new StringBuilder();
    stringBuilder
            .append("<label for=\"timezone\">Select your timezone:</label>\n")
            .append("<select name=\"timezone\">\n");
    for (final String sortedAvailableID : sortedAvailableIDs) {
      stringBuilder
              .append("  <option value=\"")
              .append(sortedAvailableID)
              .append("\">")
              .append(sortedAvailableID)
              .append("</option>\n");
    }
    stringBuilder.append("</select>\n");
    System.out.println(stringBuilder.toString());
  }

  /**
   * Generates an initialized String array for the timezone identifiers accepted by Joda DateTime on Java 15.
   */
  public static void generateTimezoneIDArray() {
    final Set<String> availableIDs = DateTimeZone.getAvailableIDs();
    final List<String> sortedAvailableIDs = new ArrayList<>();
    sortedAvailableIDs.addAll(availableIDs);
    Collections.sort(sortedAvailableIDs);
    final StringBuilder stringBuilder = new StringBuilder();
    stringBuilder
            .append("  private static final String[] TIMEZONE_IDS = {\n");
    for (final String sortedAvailableID : sortedAvailableIDs) {
      stringBuilder
              .append("    \"")
              .append(sortedAvailableID)
              .append("\",\n");
    }
    stringBuilder.setLength(stringBuilder.length() - 2);
    stringBuilder.append("\n  };\n");
    System.out.println(stringBuilder.toString());
  }
}

Answer 2

在HTML standard中没有这样的标记。您必须在后端生成列表，或者使用一个可用的前端库（例如https://momentjs.com/timezone/）。在后端生成可以保证标识符是兼容的