///

## Use cases

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. <a href="https://msgpack.org/index.html" class="external-link" target="_blank">`msgpack`</a>).
* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings

   */
  public abstract Writer openStream() throws IOException;

  /**
   * Opens a new buffered {@link Writer} for writing to this sink. The returned stream is not
   * required to be a {@link BufferedWriter} in order to allow implementations to simply delegate to
   * {@link #openStream()} when the stream returned by that method does not benefit from additional

  }

  /**
   * Wrapper for {@link Map#get(Object)} that forces the caller to pass in a key of the same type as
   * the map. Besides being slightly shorter than code that uses {@link #getMap()}, it also ensures
   * that callers don't pass an {@link Entry} by mistake.
   */
  protected V get(K key) {
    return getMap().get(key);
  }

@ElementTypesAreNonnullByDefault
public enum RemovalCause {
  /**
   * The entry was manually removed by the user. This can result from the user invoking {@link
   * Cache#invalidate}, {@link Cache#invalidateAll(Iterable)}, {@link Cache#invalidateAll()}, {@link
   * Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
   */
  EXPLICIT {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**

# 高级安全

## 附加特性

除 [教程 - 用户指南: 安全性](../../tutorial/security/index.md){.internal-link target=_blank} 中涵盖的功能之外，还有一些额外的功能来处理安全性.

/// tip | "小贴士"

接下来的章节 **并不一定是 "高级的"**.

而且对于你的使用场景来说，解决方案很可能就在其中。

///

## 先阅读教程

接下来的部分假设你已经阅读了主要的 [教程 - 用户指南: 安全性](../../tutorial/security/index.md){.internal-link target=_blank}.

/// tip

The actual callback is just an HTTP request.

When implementing the callback yourself, you could use something like <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> or <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requests</a>.

///

## Write the callback documentation code

O callback real é apenas uma solicitação HTTP.

Quando implementando o callback por você mesmo, você pode usar algo como <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> ou <a href="https://requests.readthedocs.io/" class="external-link" target="_blank">Requisições</a>.

///

## Escrevendo o código de documentação do callback

* 可获取上传文件的元数据；
* 自带 <a href="https://docs.python.org/zh-cn/3/glossary.html#term-file-like-object" class="external-link" target="_blank">file-like</a> `async` 接口；
* 暴露的 Python <a href="https://docs.python.org/zh-cn/3/library/tempfile.html#tempfile.SpooledTemporaryFile" class="external-link" target="_blank">`SpooledTemporaryFile`</a> 对象，可直接传递给其他预期「file-like」对象的库。

### `UploadFile`

`UploadFile` 的属性如下：

<c:if test="${osddLink}">
	<link rel="search" type="application/opensearchdescription+xml"
		href="${fe:url('/osdd')}"
		title="<la:message key="labels.index_osdd_title" />" />
</c:if>
<link href="${fe:url('/css/bootstrap.min.css')}" rel="stylesheet"
	type="text/css" />
<link href="${fe:url('/css/style.css')}" rel="stylesheet" type="text/css" />
<link href="${fe:url('/css/font-awesome.min.css')}" rel="stylesheet"

<c:if test="${osddLink}">
	<link rel="search" type="application/opensearchdescription+xml"
		href="${fe:url('/osdd')}"
		title="<la:message key="labels.index_osdd_title" />" />
</c:if>
<link href="${fe:url('/css/bootstrap.min.css')}" rel="stylesheet"
	type="text/css" />
<link href="${fe:url('/css/style.css')}" rel="stylesheet" type="text/css" />
<link href="${fe:url('/css/font-awesome.min.css')}" rel="stylesheet"