---
title: 使用 Messages API
url: https://platform.claude.com/docs/zh-CN/build-with-claude/working-with-messages
description: 有效使用 Messages API 的实用模式和示例
---

Anthropic 提供两种使用 Claude 进行构建的方式，每种方式适用于不同的使用场景：

|          | Messages API   | Claude Managed Agents    |
| -------- | -------------- | ------------------------ |
| **它是什么** | 直接的模型提示访问      | 预构建、可配置的智能体框架，运行在托管基础设施中 |
| **最适合**  | 自定义智能体循环和细粒度控制 | 长时间运行的任务和异步工作            |

本指南涵盖使用 Messages API 的常见模式，包括基本请求、多轮对话、预填充技术和视觉功能。有关完整的 API 规范，请参阅 [Messages API 参考](https://platform.claude.com/docs/zh-CN/api/messages/create)。如需了解托管智能体框架，请参阅 [Claude Managed Agents 概述](https://platform.claude.com/docs/zh-CN/managed-agents/overview)。

<Note>
  要了解"zero data retention"（零数据保留），即 ZDR 如何适用于此功能，请参阅 [API 与数据保留](https://platform.claude.com/docs/zh-CN/manage-claude/api-and-data-retention)。
</Note>

## 基本请求和响应

<Note>
  Claude 4.7 及更高版本的模型以及 Claude Mythos Preview 不支持 `temperature`、`top_p` 和 `top_k` 采样参数。将它们设置为非默认值会返回 400 错误。请在请求负载中省略这些参数，改用提示来引导模型的行为。请参阅[迁移指南](https://platform.claude.com/docs/zh-CN/models/opus-5-5/migration-guide#opus-46-breaking-changes)。
</Note>

<CodeGroup>
  ```bash cURL
  #!/bin/sh
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 1024,
      "messages": [
        {"role": "user", "content": "Hello, Claude"}
      ]
    }'
  ```

  ```bash CLI
  ant messages create \
    --model claude-opus-5-5 \
    --max-tokens 1024 \
    --message '{role: user, content: "Hello, Claude"}'
  ```

  ```python Python
  message = anthropic.Anthropic().messages.create(
      model="claude-opus-5-5",
      max_tokens=1024,
      messages=[{"role": "user", "content": "Hello, Claude"}],
  )
  print(message)
  ```

  ```typescript TypeScript
  const anthropic = new Anthropic();

  const message = await anthropic.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [{ role: "user", content: "Hello, Claude" }]
  });
  console.log(message);
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages = [new() { Role = Role.User, Content = "Hello, Claude" }]
  };
  var message = await client.Messages.Create(parameters);
  Console.WriteLine(message);
  ```

  ```go Go
  client := anthropic.NewClient()

  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Hello, Claude")),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(response)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addUserMessage("Hello, Claude")
      .build();

  Message response = client.messages().create(params);
  System.out.println(response);
  ```

  ```php PHP
  $client = new Client();

  $message = $client->messages->create(
      maxTokens: 1024,
      messages: [['role' => 'user', 'content' => 'Hello, Claude']],
      model: 'claude-opus-5-5',
  );
  echo json_encode($message, JSON_PRETTY_PRINT), PHP_EOL;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  message = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "Hello, Claude" }
    ]
  )
  puts message
  ```
</CodeGroup>

```json Output
{
  "id": "msg_01XFDUDYJgAACzvnptvVoYEL",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello!"
    }
  ],
  "model": "claude-opus-5-5",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 12,
    "output_tokens": 6
  }
}
```

在所有模型上，拒绝响应（`stop_reason: "refusal"`）还会包含一个 `stop_details` 对象，用于标识触发拒绝的策略类别。有关字段参考和示例处理代码，请参阅[处理停止原因](https://platform.claude.com/docs/zh-CN/build-with-claude/refusals-and-fallback#refusal-response)。

## 多轮对话

Messages API 是无状态的，这意味着您始终需要将完整的对话历史发送给 API。您可以使用这种模式逐步构建对话。较早的对话轮次不一定需要真正来自 Claude。您可以使用合成的 `assistant` 消息。

<CodeGroup>
  ```bash cURL
  #!/bin/sh
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 1024,
      "messages": [
        {"role": "user", "content": "Hello, Claude"},
        {"role": "assistant", "content": "Hello!"},
        {"role": "user", "content": "Can you describe LLMs to me?"}

      ]
    }'
  ```

  ```bash CLI
  ant messages create \
    --model claude-opus-5-5 \
    --max-tokens 1024 \
    --message '{role: user, content: "Hello, Claude"}' \
    --message '{role: assistant, content: "Hello!"}' \
    --message '{role: user, content: "Can you describe LLMs to me?"}'
  ```

  ```python Python
  message = anthropic.Anthropic().messages.create(
      model="claude-opus-5-5",
      max_tokens=1024,
      messages=[
          {"role": "user", "content": "Hello, Claude"},
          {"role": "assistant", "content": "Hello!"},
          {"role": "user", "content": "Can you describe LLMs to me?"},
      ],
  )
  print(message)
  ```

  ```typescript TypeScript
  const anthropic = new Anthropic();

  const message = await anthropic.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "Hello, Claude" },
      { role: "assistant", content: "Hello!" },
      { role: "user", content: "Can you describe LLMs to me?" }
    ]
  });
  console.log(message);
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages =
      [
          new() { Role = Role.User, Content = "Hello, Claude" },
          new() { Role = Role.Assistant, Content = "Hello!" },
          new() { Role = Role.User, Content = "Can you describe LLMs to me?" }
      ]
  };

  var message = await client.Messages.Create(parameters);
  Console.WriteLine(message);
  ```

  ```go Go
  client := anthropic.NewClient()

  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Hello, Claude")),
  		anthropic.NewAssistantMessage(anthropic.NewTextBlock("Hello!")),
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Can you describe LLMs to me?")),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(response)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addUserMessage("Hello, Claude")
      .addAssistantMessage("Hello!")
      .addUserMessage("Can you describe LLMs to me?")
      .build();

  Message response = client.messages().create(params);
  System.out.println(response);
  ```

  ```php PHP
  $client = new Client();

  $message = $client->messages->create(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'Hello, Claude'],
          ['role' => 'assistant', 'content' => 'Hello!'],
          ['role' => 'user', 'content' => 'Can you describe LLMs to me?'],
      ],
      model: 'claude-opus-5-5',
  );

  echo json_encode($message, JSON_PRETTY_PRINT), PHP_EOL;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  message = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "Hello, Claude" },
      { role: "assistant", content: "Hello!" },
      { role: "user", content: "Can you describe LLMs to me?" }
    ]
  )
  puts message
  ```
</CodeGroup>

```json Output
{
  "id": "msg_018gCsTGsXkYJVqYPxTgDHBU",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Sure, I'd be happy to provide..."
    }
  ],
  "model": "claude-opus-5-5",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 30,
    "output_tokens": 309
  }
}
```

### 消息中的 system 角色

在 Claude Fable 5.1、[Claude Mythos 5.1](https://platform.claude.com/docs/zh-CN/models/mythos-5-1/overview)、Claude Fable 5、[Claude Mythos 5](https://platform.claude.com/docs/zh-CN/models/mythos-5/overview)、Claude Opus 5.5、Claude Opus 4.8、Claude Opus 5、Claude Sonnet 5.5 和 Claude Haiku 5.5 上，您可以在用户轮次之后包含 `"role": "system"` 的消息（需遵守[放置规则](https://platform.claude.com/docs/zh-CN/build-with-claude/mid-conversation-system-messages#limitations)），以便在对话中途添加新的系统指令。携带内容的 `system` 消息不能作为 `messages` 中的第一个条目。对于从一开始就适用的指令，请使用顶层 `system` 字段。

对话中途的系统消息与顶层 `system` 字段具有相同的权威性，但由于它被追加到消息历史的末尾，因此不会使其之前的任何已缓存前缀失效。对于应从第一轮就适用的指令，请使用顶层 `system` 字段；对于仅在稍后才变得相关的指令，请使用对话中途的系统消息。

请参阅[对话中途的系统消息](https://platform.claude.com/docs/zh-CN/build-with-claude/mid-conversation-system-messages)获取完整指南，包括如何将其与 "prompt caching"（提示缓存）结合使用，详见[提示缓存](https://platform.claude.com/docs/zh-CN/build-with-claude/prompt-caching)。

## 预填充 Claude 的响应

您可以在输入消息列表的最后一个位置预填充 Claude 响应的一部分。使用此技术可以塑造 Claude 的响应。以下示例使用 `"max_tokens": 1` 从 Claude 获取单个多项选择答案。

<Warning>
  Claude 4.6 及更高版本的模型以及 [Claude Mythos Preview](https://anthropic.com/glasswing) 不支持预填充。对这些模型使用预填充的请求会返回 400 错误。请改为在支持的模型上使用[结构化输出](https://platform.claude.com/docs/zh-CN/build-with-claude/structured-outputs)，或使用系统提示指令。有关迁移模式，请参阅[迁移指南](https://platform.claude.com/docs/zh-CN/about-claude/models/migration-guide)。
</Warning>

<CodeGroup>
  ```bash cURL
  #!/bin/sh
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-sonnet-4-5",
      "max_tokens": 1,
      "messages": [
        {"role": "user", "content": "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae"},
        {"role": "assistant", "content": "The answer is ("}
      ]
    }'
  ```

  ```bash CLI
  ant messages create <<'YAML'
  model: claude-sonnet-4-5
  max_tokens: 1
  messages:
    - role: user
      content: "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae"
    - role: assistant
      content: "The answer is ("
  YAML
  ```

  ```python Python
  message = anthropic.Anthropic().messages.create(
      model="claude-sonnet-4-5",
      max_tokens=1,
      messages=[
          {
              "role": "user",
              "content": "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae",
          },
          {"role": "assistant", "content": "The answer is ("},
      ],
  )
  print(message)
  ```

  ```typescript TypeScript
  const anthropic = new Anthropic();

  const message = await anthropic.messages.create({
    model: "claude-sonnet-4-5",
    max_tokens: 1,
    messages: [
      {
        role: "user",
        content: "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae"
      },
      { role: "assistant", content: "The answer is (" }
    ]
  });
  console.log(message);
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeSonnet4_5,
      MaxTokens = 1,
      Messages = [
          new() { Role = Role.User, Content = "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae" },
          new() { Role = Role.Assistant, Content = "The answer is (" }
      ]
  };

  var message = await client.Messages.Create(parameters);
  Console.WriteLine(message);
  ```

  ```go Go
  client := anthropic.NewClient()

  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeSonnet4_5,
  	MaxTokens: 1,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae")),
  		anthropic.NewAssistantMessage(anthropic.NewTextBlock("The answer is (")),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(response)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_SONNET_4_5)
      .maxTokens(1L)
      .addUserMessage("What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae")
      .addAssistantMessage("The answer is (")
      .build();

  Message response = client.messages().create(params);
  System.out.println(response);
  ```

  ```php PHP
  $client = new Client();

  $message = $client->messages->create(
      maxTokens: 1,
      messages: [
          ['role' => 'user', 'content' => 'What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae'],
          ['role' => 'assistant', 'content' => 'The answer is ('],
      ],
      model: 'claude-sonnet-4-5',
  );
  echo $message->content[0]->text;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  message = client.messages.create(
    model: "claude-sonnet-4-5",
    max_tokens: 1,
    messages: [
      {
        role: "user",
        content: "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae"
      },
      { role: "assistant", content: "The answer is (" }
    ]
  )
  puts message
  ```
</CodeGroup>

```json Output
{
  "id": "msg_01Q8Faay6S7QPTvEUUQARt7h",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "C"
    }
  ],
  "model": "claude-sonnet-4-5",
  "stop_reason": "max_tokens",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 42,
    "output_tokens": 1
  }
}
```

## 视觉

Claude 可以读取请求中的文本和图像。您可以使用 `base64`、`url` 或 `file` 源类型提供图像。`file` 源类型引用通过 [Files API](https://platform.claude.com/docs/zh-CN/build-with-claude/files) 上传的图像。支持的媒体类型为 `image/jpeg`、`image/png`、`image/gif` 和 `image/webp`。有关更多详细信息，请参阅[视觉指南](https://platform.claude.com/docs/zh-CN/build-with-claude/vision)。

<CodeGroup>
  ```bash cURL
  #!/bin/sh

  # 选项 1：Base64 编码的图像
  IMAGE_URL="https://platform.claude.com/docs/images/vision-example.jpg"
  IMAGE_MEDIA_TYPE="image/jpeg"
  IMAGE_BASE64=$(curl "$IMAGE_URL" | base64 | tr -d '\n')

  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d @- <<EOF
  {
    "model": "claude-opus-5-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": [
        {"type": "image", "source": {
          "type": "base64",
          "media_type": "$IMAGE_MEDIA_TYPE",
          "data": "$IMAGE_BASE64"
        }},
        {"type": "text", "text": "What is in the above image?"}
      ]}
    ]
  }
  EOF

  # 选项 2：通过 URL 引用的图像
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 1024,
      "messages": [
        {"role": "user", "content": [
          {"type": "image", "source": {
            "type": "url",
            "url": "https://platform.claude.com/docs/images/vision-example.jpg"
          }},
          {"type": "text", "text": "What is in the above image?"}
        ]}
      ]
    }'
  ```

  ```bash CLI
  IMAGE_URL="https://platform.claude.com/docs/images/vision-example.jpg"

  # 选项 1：Base64 编码的图像（CLI 会自动编码二进制 @file 引用）
  curl -s "$IMAGE_URL" -o ./vision-example.jpg

  ant messages create <<'YAML'
  model: claude-opus-5-5
  max_tokens: 1024
  messages:
    - role: user
      content:
        - type: image
          source:
            type: base64
            media_type: image/jpeg
            data: "@./vision-example.jpg"
        - type: text
          text: What is in the above image?
  YAML

  # 选项 2：通过 URL 引用的图像
  ant messages create <<YAML
  model: claude-opus-5-5
  max_tokens: 1024
  messages:
    - role: user
      content:
        - type: image
          source:
            type: url
            url: $IMAGE_URL
        - type: text
          text: What is in the above image?
  YAML
  ```

  ```python Python
  import base64
  import httpx2

  # 选项 1：Base64 编码的图像
  image_url = "https://platform.claude.com/docs/images/vision-example.jpg"
  image_media_type = "image/jpeg"
  image_data = base64.standard_b64encode(httpx2.get(image_url).content).decode("utf-8")

  message = anthropic.Anthropic().messages.create(
      model="claude-opus-5-5",
      max_tokens=1024,
      messages=[
          {
              "role": "user",
              "content": [
                  {
                      "type": "image",
                      "source": {
                          "type": "base64",
                          "media_type": image_media_type,
                          "data": image_data,
                      },
                  },
                  {"type": "text", "text": "What is in the above image?"},
              ],
          }
      ],
  )
  print(message)

  # 选项 2：通过 URL 引用的图像
  message_from_url = anthropic.Anthropic().messages.create(
      model="claude-opus-5-5",
      max_tokens=1024,
      messages=[
          {
              "role": "user",
              "content": [
                  {
                      "type": "image",
                      "source": {
                          "type": "url",
                          "url": "https://platform.claude.com/docs/images/vision-example.jpg",
                      },
                  },
                  {"type": "text", "text": "What is in the above image?"},
              ],
          }
      ],
  )
  print(message_from_url)
  ```

  ```typescript TypeScript
  const anthropic = new Anthropic();

  // 选项 1：Base64 编码的图像
  const imageUrl = "https://platform.claude.com/docs/images/vision-example.jpg";
  const imageMediaType = "image/jpeg";
  const imageArrayBuffer = await (await fetch(imageUrl)).arrayBuffer();
  const imageData = Buffer.from(imageArrayBuffer).toString("base64");

  const message = await anthropic.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: [
          {
            type: "image",
            source: {
              type: "base64",
              media_type: imageMediaType,
              data: imageData
            }
          },
          {
            type: "text",
            text: "What is in the above image?"
          }
        ]
      }
    ]
  });
  console.log(message);

  // 选项 2：通过 URL 引用的图像
  const messageFromUrl = await anthropic.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: [
          {
            type: "image",
            source: {
              type: "url",
              url: "https://platform.claude.com/docs/images/vision-example.jpg"
            }
          },
          {
            type: "text",
            text: "What is in the above image?"
          }
        ]
      }
    ]
  });
  console.log(messageFromUrl);
  ```

  ```csharp C#
  using System.Collections.Generic;
  using System.Net.Http;
  using Anthropic;
  using Anthropic.Models.Messages;

  AnthropicClient client = new();

  // 选项 1：Base64 编码的图像
  string imageUrl = "https://platform.claude.com/docs/images/vision-example.jpg";

  using HttpClient httpClient = new();
  byte[] imageBytes = await httpClient.GetByteArrayAsync(imageUrl);
  string imageData = Convert.ToBase64String(imageBytes);

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages =
      [
          new()
          {
              Role = Role.User,
              Content = new MessageParamContent(new List<ContentBlockParam>
              {
                  new ContentBlockParam(new ImageBlockParam(
                      new ImageBlockParamSource(new Base64ImageSource()
                      {
                          Data = imageData,
                          MediaType = MediaType.ImageJpeg,
                      })
                  )),
                  new ContentBlockParam(new TextBlockParam("What is in the above image?")),
              }),
          }
      ]
  };

  var message = await client.Messages.Create(parameters);
  Console.WriteLine(message);

  // 选项 2：通过 URL 引用的图像
  var parametersFromUrl = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages =
      [
          new()
          {
              Role = Role.User,
              Content = new MessageParamContent(new List<ContentBlockParam>
              {
                  new ContentBlockParam(new ImageBlockParam(
                      new ImageBlockParamSource(new UrlImageSource()
                      {
                          Url = "https://platform.claude.com/docs/images/vision-example.jpg",
                      })
                  )),
                  new ContentBlockParam(new TextBlockParam("What is in the above image?")),
              }),
          }
      ]
  };

  var messageFromUrl = await client.Messages.Create(parametersFromUrl);
  Console.WriteLine(messageFromUrl);
  ```

  ```go Go
  client := anthropic.NewClient()

  // 选项 1：Base64 编码的图像
  imageURL := "https://platform.claude.com/docs/images/vision-example.jpg"

  req, err := http.NewRequest("GET", imageURL, nil)
  if err != nil {
  	log.Fatal(err)
  }
  req.Header.Set("User-Agent", "AnthropicDocsBot/1.0")

  resp, err := http.DefaultClient.Do(req)
  if err != nil {
  	log.Fatal(err)
  }
  defer resp.Body.Close()

  imageBytes, err := io.ReadAll(resp.Body)
  if err != nil {
  	log.Fatal(err)
  }
  imageData := base64.StdEncoding.EncodeToString(imageBytes)

  message, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(
  			anthropic.NewImageBlockBase64("image/jpeg", imageData),
  			anthropic.NewTextBlock("What is in the above image?"),
  		),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(message)

  // 选项 2：通过 URL 引用的图像
  messageFromURL, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(
  			anthropic.NewImageBlock(anthropic.URLImageSourceParam{
  				URL: "https://platform.claude.com/docs/images/vision-example.jpg",
  			}),
  			anthropic.NewTextBlock("What is in the above image?"),
  		),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(messageFromURL)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  // 选项 1：Base64 编码的图像
  String imageUrl = "https://platform.claude.com/docs/images/vision-example.jpg";

  HttpClient httpClient = HttpClient.newHttpClient();
  HttpRequest request = HttpRequest.newBuilder().uri(URI.create(imageUrl)).build();
  HttpResponse<byte[]> response = httpClient.send(request, HttpResponse.BodyHandlers.ofByteArray());
  String imageData = Base64.getEncoder().encodeToString(response.body());

  List<ContentBlockParam> base64Content = List.of(
      ContentBlockParam.ofImage(
          ImageBlockParam.builder()
              .source(Base64ImageSource.builder()
                  .data(imageData)
                  .mediaType(Base64ImageSource.MediaType.IMAGE_JPEG)
                  .build())
              .build()),
      ContentBlockParam.ofText(
          TextBlockParam.builder()
              .text("What is in the above image?")
              .build())
  );

  Message message = client.messages().create(
      MessageCreateParams.builder()
          .model(Model.CLAUDE_OPUS_5_5)
          .maxTokens(1024L)
          .addUserMessageOfBlockParams(base64Content)
          .build());
  System.out.println(message);

  // 选项 2：通过 URL 引用的图像
  List<ContentBlockParam> urlContent = List.of(
      ContentBlockParam.ofImage(
          ImageBlockParam.builder()
              .source(UrlImageSource.builder()
                  .url("https://platform.claude.com/docs/images/vision-example.jpg")
                  .build())
              .build()),
      ContentBlockParam.ofText(
          TextBlockParam.builder()
              .text("What is in the above image?")
              .build())
  );

  Message messageFromUrl = client.messages().create(
      MessageCreateParams.builder()
          .model(Model.CLAUDE_OPUS_5_5)
          .maxTokens(1024L)
          .addUserMessageOfBlockParams(urlContent)
          .build());
  System.out.println(messageFromUrl);
  ```

  ```php PHP
  $client = new Client();

  // 选项 1：Base64 编码的图像
  $image_url = 'https://platform.claude.com/docs/images/vision-example.jpg';
  $image_media_type = "image/jpeg";
  $image_data = base64_encode(file_get_contents($image_url));

  $message = $client->messages->create(
      maxTokens: 1024,
      messages: [
          [
              'role' => 'user',
              'content' => [
                  [
                      'type' => 'image',
                      'source' => [
                          'type' => 'base64',
                          'media_type' => $image_media_type,
                          'data' => $image_data,
                      ],
                  ],
                  [
                      'type' => 'text',
                      'text' => 'What is in the above image?',
                  ],
              ],
          ],
      ],
      model: 'claude-opus-5-5',
  );
  echo $message;

  // 选项 2：通过 URL 引用的图像
  $message_from_url = $client->messages->create(
      maxTokens: 1024,
      messages: [
          [
              'role' => 'user',
              'content' => [
                  [
                      'type' => 'image',
                      'source' => [
                          'type' => 'url',
                          'url' => 'https://platform.claude.com/docs/images/vision-example.jpg',
                      ],
                  ],
                  [
                      'type' => 'text',
                      'text' => 'What is in the above image?',
                  ],
              ],
          ],
      ],
      model: 'claude-opus-5-5',
  );
  echo $message_from_url;
  ```

  ```ruby Ruby
  require "base64"
  require "net/http"

  client = Anthropic::Client.new

  # 选项 1：Base64 编码的图像
  image_url = "https://platform.claude.com/docs/images/vision-example.jpg"
  image_media_type = "image/jpeg"
  image_data = Base64.strict_encode64(Net::HTTP.get(URI(image_url)))

  message = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: [
          {
            type: "image",
            source: {
              type: "base64",
              media_type: image_media_type,
              data: image_data
            }
          },
          {
            type: "text",
            text: "What is in the above image?"
          }
        ]
      }
    ]
  )
  puts message

  # 选项 2：通过 URL 引用的图像
  message_from_url = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: [
          {
            type: "image",
            source: {
              type: "url",
              url: "https://platform.claude.com/docs/images/vision-example.jpg"
            }
          },
          {
            type: "text",
            text: "What is in the above image?"
          }
        ]
      }
    ]
  )
  puts message_from_url
  ```
</CodeGroup>

```json Output
{
  "id": "msg_011CdKmWtV3oFx1C5yUbf5CY",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "This image is a beautiful minimalist/flat-design illustration of a sunset landscape. Here's what it contains:\n\n**Sky & Sun:**\n- A warm gradient sky transitioning from golden-yellow at the top to deep orange toward the horizon\n- A large pale yellow sun positioned in the upper-right area\n\n**Birds:**\n- Three small silhouetted birds flying in the upper-left portion of the sky, depicted as simple \"M\" or \"v\" shapes\n\n**Mountains:**\n- Multiple layered mountain peaks in purple and maroon tones\n- The mountains overlap to create depth, with varying shades of dusty purple and deep burgundy\n\n**Water:**\n- A dark purple body of water at the bottom of the image\n- A reflection of the sun shown as horizontal cream/peach colored lines in the center-bottom area\n\nThe overall style is clean, geometric, and uses a warm sunset color palette (oranges, yellows, purples, and maroons), giving it a peaceful, serene aesthetic typical of modern vector/flat design artwork."
    }
  ],
  "model": "claude-opus-5-5",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 1030,
    "output_tokens": 350
  }
}
```

## 后续步骤

<CardGroup cols={2}>
  <Card title="停止原因和回退" icon="list" href="https://platform.claude.com/docs/zh-CN/build-with-claude/handling-stop-reasons">
    处理每个 `stop_reason` 值，并决定响应结束时该做什么。
  </Card>

  <Card title="使用 Claude 进行工具使用" icon="wrench" href="https://platform.claude.com/docs/zh-CN/agents-and-tools/tool-use/overview">
    为 Claude 提供工具，以便在 Messages API 中调用外部服务和 API。
  </Card>

  <Card title="计算机使用工具" icon="computer" href="https://platform.claude.com/docs/zh-CN/agents-and-tools/tool-use/computer-use-tool">
    使用 Messages API 控制桌面计算机环境。
  </Card>

  <Card title="浏览器使用工具" icon="browser" href="https://platform.claude.com/docs/zh-CN/agents-and-tools/tool-use/browser-use-tool">
    让 Claude 在您运行的浏览器中导航、阅读网页并与之交互。
  </Card>

  <Card title="结构化输出" icon="code-brackets" href="https://platform.claude.com/docs/zh-CN/build-with-claude/structured-outputs">
    从 Claude 获取有保证的、经过模式验证的 JSON 输出。
  </Card>

  <Card title="任务预算" icon="gauge" href="https://platform.claude.com/docs/zh-CN/build-with-claude/task-budgets">
    使用 `output_config.task_budget` 为整个智能体循环设置建议性的令牌预算。
  </Card>
</CardGroup>