使用路径装饰器依赖项还可以避免开发新人误会代码中包含无用的未使用参数。

///

/// info | "说明"

本例中，使用的是自定义响应头 `X-Key` 和 `X-Token`。

但实际开发中，尤其是在实现安全措施时，最好使用 FastAPI 内置的[安全工具](../security/index.md){.internal-link target=_blank}（详见下一章）。

///

## 依赖项错误和返回值

路径装饰器依赖项也可以使用普通的依赖项*函数*。

### 依赖项的需求项

路径装饰器依赖项可以声明请求的需求项（比如响应头）或其他子依赖项：

```Python hl_lines="6  11"
{!../../docs_src/dependencies/tutorial006.py!}

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import junit.framework.Test;
import junit.framework.TestSuite;

/**
 * Generates a test suite covering the {@link Queue} implementations in the {@link java.util}
 * package. Can be subclassed to specify tests that should be suppressed.
 *
 * @author Jared Levy
 */
@GwtIncompatible
public class TestsForQueuesInJavaUtil {

import com.google.common.collect.testing.testers.TestExceptions.SomeUncheckedException;
import java.util.Map;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#compute}. Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import com.google.common.collect.ImmutableList;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link Graphs#hasCycle(Graph)} and {@link Graphs#hasCycle(Network)}. */
// TODO(user): Consider moving this to GraphsTest.
@RunWith(JUnit4.class)
public class GraphPropertiesTest {
  ImmutableList<MutableGraph<Integer>> graphsToTest;

import com.google.common.collect.testing.features.ListFeature;
import java.util.List;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Test suite covering {@link Floats#asList(float[])})}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
public class FloatArrayAsListTest extends TestCase {

  private static List<Float> asList(Float[] values) {

import com.google.common.collect.testing.testers.TestExceptions.SomeUncheckedException;
import java.util.Map;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#compute}. Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import com.google.common.collect.testing.features.ListFeature;
import java.util.List;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Test suite covering {@link Floats#asList(float[])})}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
public class FloatArrayAsListTest extends TestCase {

  private static List<Float> asList(Float[] values) {

import com.google.common.collect.testing.features.ListFeature;
import java.util.List;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Test suite covering {@link Ints#asList(int[])}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@SuppressWarnings("cast") // redundant casts are intentional and harmless
public class IntArrayAsListTest extends TestCase {

import java.io.OutputStream;
import java.nio.file.attribute.PosixFileAttributeView;
import java.nio.file.attribute.PosixFileAttributes;
import java.util.Arrays;

/**
 * Unit tests for {@link FileBackedOutputStream}.
 *
 * <p>For a tiny bit more testing, see {@link FileBackedOutputStreamAndroidIncompatibleTest}.
 *
 * @author Chris Nokleberg
 */
public class FileBackedOutputStreamTest extends IoTestCase {

import org.apache.maven.model.v4.MavenStaxWriter;
import org.codehaus.plexus.util.xml.XmlStreamWriter;

/**
 * Handles serialization of a model into some kind of textual format like XML.
 *
 * @deprecated use {@link XmlStreamWriter} instead
 */
@Named
@Singleton
@Deprecated(since = "4.0.0")
public class DefaultModelWriter implements ModelWriter {

    @Override