static <T> IdentityLoader<T> identityLoader() {
    return new IdentityLoader<T>();
  }

  /**
   * Returns a {@code new Object()} for every request, and increments a counter for every request.
   * The count is accessible via {@link #getCount}.
   */
  static class CountingLoader extends CacheLoader<Object, Object> {
    private final AtomicInteger count = new AtomicInteger();

# Lernen { #learn }

Hier sind die einführenden Abschnitte und Tutorials, um **FastAPI** zu lernen.

  private WorkerRunningState workerRunningState = IDLE;

  /**
   * This counter prevents an ABA issue where a thread may successfully schedule the worker, the
   * worker runs and exhausts the queue, another thread enqueues a task and fails to schedule the
   * worker, and then the first thread's call to delegate.execute() returns. Without this counter,
   * it would observe the QUEUING state and set it to QUEUED, and the worker would never be

/// note | 技術細節

你也可以使用 `from starlette.staticfiles import StaticFiles`。

**FastAPI** 為了方便開發者，提供與 `starlette.staticfiles` 相同的介面作為 `fastapi.staticfiles`。但它其實是直接來自 Starlette。

///

### 什麼是「掛載」 { #what-is-mounting }

「掛載（mounting）」是指在特定路徑下加入一個完整且「獨立」的應用，之後所有該路徑下的子路徑都由它處理。

這與使用 `APIRouter` 不同，因為被掛載的應用是完全獨立的。主應用的 OpenAPI 與文件不會包含掛載應用的任何內容，等等。

你可以在[進階使用者指南](../advanced/index.md)中閱讀更多相關內容。

## 細節 { #details }

import org.bouncycastle.crypto.generators.KDFCounterBytesGenerator;
import org.bouncycastle.crypto.macs.HMac;
import org.bouncycastle.crypto.params.KDFCounterParameters;

/**
 * SMB3 SP800-108 Counter Mode Key Derivation
 *
 * @author mbechler
 *
 */
public final class Smb3KeyDerivation {

    private static final byte[] SIGNCONTEXT_300 = toCBytes("SmbSign");

Wenn Sie diese optionalen Abhängigkeiten nicht haben möchten, können Sie stattdessen `pip install fastapi` installieren.

Wenn Sie die Standard-Abhängigkeiten, aber ohne das `fastapi-cloud-cli` installieren möchten, können Sie mit `pip install "fastapi[standard-no-fastapi-cloud-cli]"` installieren.

///

/// tip | Tipp

```html
<a href="/items/42">
```

## Templates and static files { #templates-and-static-files }

You can also use `url_for()` inside of the template, and use it, for example, with the `StaticFiles` you mounted with the `name="static"`.

```jinja hl_lines="4"
{!../../docs_src/templates/templates/item.html!}
```

In this example, it would link to a CSS file at `static/styles.css` with:

```CSS hl_lines="4"

Wenn etwas für Ihr Projekt interessant und nützlich erscheint, lesen Sie es, andernfalls überspringen Sie es einfach.

/// tip | Tipp

Wenn Sie strukturiert **FastAPI lernen** möchten (empfohlen), lesen Sie stattdessen Kapitel für Kapitel das [Tutorial – Benutzerhandbuch](../tutorial/index.md).

type MetricType int

const (
	// CounterMT - represents a counter metric.
	CounterMT MetricType = iota
	// GaugeMT - represents a gauge metric.
	GaugeMT
	// HistogramMT - represents a histogram metric.
	HistogramMT
)

// rangeL - represents a range label.
const rangeL = "range"

func (mt MetricType) String() string {
	switch mt {
	case CounterMT:
		return "counter"
	case GaugeMT:
		return "gauge"
	case HistogramMT:

            // If we need more bytes, hash again with counter
            int counter = 1;
            while (derived.length > hash.length * counter) {
                md.update(input);
                md.update((byte) counter);
                hash = md.digest();
                int copyLen = Math.min(length - (hash.length * counter), hash.length);