import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;
import junit.framework.TestCase;

/**
 * Tests for {@link InetAddresses}.
 *
 * @author Erik Kline
 */
public class InetAddressesTest extends TestCase {

  public void testNulls() {

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.charset.Charset;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;

	RSP
	RPC
)

// Arch wraps the link architecture object with more architecture-specific information.
type Arch struct {
	*obj.LinkArch
	// Map of instruction names to enumeration.
	Instructions map[string]obj.As
	// Map of register names to enumeration.
	Register map[string]int16
	// Table of register prefix names. These are things like R for R(0) and SPR for SPR(268).
	RegisterPrefix map[string]bool

```Python hl_lines="6  11"
{!../../docs_src/path_params/tutorial003.py!}
```

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值

路径操作使用 Python 的 <abbr title="Enumeration">`Enum`</abbr> 类型接收预设的*路径参数*。

### 创建 `Enum` 类

导入 `Enum` 并创建继承自 `str` 和 `Enum` 的子类。

通过从 `str` 继承，API 文档就能把值的类型定义为**字符串**，并且能正确渲染。

然后，创建包含固定值的类属性，这些固定值是可用的有效值：

```Python hl_lines="1  6-9"

<p>
The form <code>a … b</code> represents the set of characters from
<code>a</code> through <code>b</code> as alternatives. The horizontal
ellipsis <code>…</code> is also used elsewhere in the spec to informally denote various
enumerations or code snippets that are not further specified. The character <code>…</code>
(as opposed to the three characters <code>...</code>) is not a token of the Go
language.
</p>

<p>

import java.net.Proxy;
import java.net.Proxy.Type;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

        int n, level;
        String name;

        Config.setProperty( "jcifs.smb1.smb.client.soTimeout", "600000" );
        Config.setProperty( "jcifs.smb1.smb.client.attrExpirationPeriod", "300000" );

        Enumeration e = getInitParameterNames();
        while( e.hasMoreElements() ) {
            name = (String)e.nextElement();
            if( name.startsWith( "jcifs.smb1." )) {

      this.millis = millis;
      this.label = label;
    }

    @Override
    public String toString() {
      return label;
    }
  }

  /** Convenient subsets of the {@link Timeout} enumeration for specifying scenario outcomes. */
  private enum TimeoutsToUse {
    ANY(Timeout.values()),
    PAST(Timeout.MIN, Timeout.MINUS_SMALL, Timeout.ZERO),
    FUTURE(Timeout.SMALL, Timeout.MAX),
    SMALL(Timeout.SMALL),

	cmd.PersistentFlags().StringVar(&workloadsNamespace, "workload-namespace", "",
		"Filter workloads by namespace field")

	return cmd
}

// Level is an enumeration of all supported log levels.
type Level int

const (
	defaultLoggerName = "level"
)

const (
	// OffLevel disables logging
	OffLevel Level = iota

      this.millis = millis;
      this.label = label;
    }

    @Override
    public String toString() {
      return label;
    }
  }

  /** Convenient subsets of the {@link Timeout} enumeration for specifying scenario outcomes. */
  private enum TimeoutsToUse {
    ANY(Timeout.values()),
    PAST(Timeout.MIN, Timeout.MINUS_SMALL, Timeout.ZERO),
    FUTURE(Timeout.SMALL, Timeout.MAX),
    SMALL(Timeout.SMALL),