public static final String XERCES_FEATURE_PREFIX = "http://apache.org/xml/features/";

    public static final String LOAD_EXTERNAL_DTD_FEATURE = "nonvalidating/load-external-dtd";

    public static final String FESEN_TYPE_CLOUD = "cloud";

    public static final String FESEN_TYPE_AWS = "aws";

    public static final String FESEN_USERNAME = "fesen.username";

* 数据转换
* 数据校验
* 自动生成文档

## 特殊的类型和校验

除了普通的单一值类型（如 `str`、`int`、`float` 等）外，你还可以使用从 `str` 继承的更复杂的单一值类型。

要了解所有的可用选项，请查看关于 <a href="https://docs.pydantic.dev/latest/concepts/types/" class="external-link" target="_blank">来自 Pydantic 的外部类型</a> 的文档。你将在下一章节中看到一些示例。

例如，在 `Image` 模型中我们有一个 `url` 字段，我们可以把它声明为 Pydantic 的 `HttpUrl`，而不是 `str`：

//// tab | Python 3.10+

```Python hl_lines="2  8"

 * {@link TypeToken#resolveType} since it's simpler and more type safe. This class should only be
 * used when the type mapping isn't implied by the static type hierarchy, but provided through other
 * means such as an annotation or external configuration file.
 *
 * @author Ben Yu
 * @since 15.0
 */
@ElementTypesAreNonnullByDefault
public final class TypeResolver {

  private final TypeTable typeTable;

  public TypeResolver() {

    <profile>
      <id>open-jre-modules</id>
      <activation>
        <jdk>[9,]</jdk>
      </activation>
      <properties>
        <!--
            Some tests need reflective access to the internals of these packages. It is only the
            tests themselves and not the code being tested that needs that access, though there's no
            obvious way to ensure that.

    <profile>
      <id>open-jre-modules</id>
      <activation>
        <jdk>[9,]</jdk>
      </activation>
      <properties>
        <!--
            Some tests need reflective access to the internals of these packages. It is only the
            tests themselves and not the code being tested that needs that access, though there's no
            obvious way to ensure that.

complex, or string constant.
</p>

<p>
Implementation restriction: Although numeric constants have arbitrary
precision in the language, a compiler may implement them using an
internal representation with limited precision.  That said, every
implementation must:
</p>

<ul>
	<li>Represent integer constants with at least 256 bits.</li>

  // must be specified.
  //
  // The `host` should not refer to a service running in the cluster; use
  // the `service` field instead. The host might be resolved via external
  // DNS in some apiservers (e.g., `kube-apiserver` cannot resolve
  // in-cluster DNS as that would be a layering violation). `host` may
  // also be an IP address.
  //

          "format": "time_series",
          "interval": "",
          "intervalFactor": 1,
          "legendFormat": "P50",
          "refId": "A"
        },
        {
          "datasource": {
            "type": "prometheus",

ntent:"\f06a"}.fa-exclamation-triangle:before{content:"\f071"}.fa-expand:before{content:"\f065"}.fa-expand-alt:before{content:"\f424"}.fa-expand-arrows-alt:before{content:"\f31e"}.fa-expeditedssl:before{content:"\f23e"}.fa-external-link-alt:before{content:"\f35d"}.fa-external-link-square-alt:before{content:"\f360"}.fa-eye:before{content:"\f06e"}.fa-eye-dropper:before{content:"\f1fb"}.fa-eye-slash:before{content:"\f070"}.fa-facebook:before{content:"\f09a"}.fa-facebook-f:before{content:"\f39e"}.fa...

* データ変換
* データの検証
* 自動文書化

## 特殊な型とバリデーション

`str`や`int`、`float`のような通常の単数型の他にも、`str`を継承したより複雑な単数型を使うこともできます。

すべてのオプションをみるには、<a href="https://docs.pydantic.dev/latest/concepts/types/" class="external-link" target="_blank">Pydanticのエキゾチック な型</a>のドキュメントを確認してください。次の章でいくつかの例をみることができます。

例えば、`Image`モデルのように`url`フィールドがある場合、`str`の代わりにPydanticの`HttpUrl`を指定することができます:

```Python hl_lines="4 10"