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参考数据：Claude API 参考 — Java ​

Data: Claude API reference — Java

v2.1.63

Java SDK reference including installation, client initialization, basic requests, streaming, and beta tool use

Claude API — Java ​

注意： Java SDK 支持 Claude API 和带注解类的 beta 工具使用。Agent SDK 目前尚未适用于 Java。

安装 ​

Maven：

xml
<dependency>
    <groupId>com.anthropic</groupId>
    <artifactId>anthropic-java</artifactId>
    <version>2.15.0</version>
</dependency>

Gradle：

groovy
implementation("com.anthropic:anthropic-java:2.15.0")

客户端初始化 ​

java
import com.anthropic.client.AnthropicClient;
import com.anthropic.client.okhttp.AnthropicOkHttpClient;

// 默认方式（从环境变量读取 ANTHROPIC_API_KEY）
AnthropicClient client = AnthropicOkHttpClient.fromEnv();

// 显式指定 API 密钥
AnthropicClient client = AnthropicOkHttpClient.builder()
    .apiKey("your-api-key")
    .build();

基础消息请求 ​

java
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.Model;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("What is the capital of France?")
    .build();

Message response = client.messages().create(params);
response.content().stream()
    .flatMap(block -> block.text().stream())
    .forEach(textBlock -> System.out.println(textBlock.text()));

流式传输 ​

java
import com.anthropic.core.http.StreamResponse;
import com.anthropic.models.messages.RawMessageStreamEvent;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("Write a haiku")
    .build();

try (StreamResponse<RawMessageStreamEvent> streamResponse = client.messages().createStreaming(params)) {
    streamResponse.stream()
        .flatMap(event -> event.contentBlockDelta().stream())
        .flatMap(deltaEvent -> deltaEvent.delta().text().stream())
        .forEach(textDelta -> System.out.print(textDelta.text()));
}

工具使用（Beta） ​

Java SDK 支持通过带注解的类进行 beta 工具使用。工具类实现 Supplier<String> 接口，可通过 BetaToolRunner 自动执行。

工具运行器（自动循环） ​

java
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.BetaMessage;
import com.anthropic.helpers.BetaToolRunner;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonPropertyDescription;
import java.util.function.Supplier;

@JsonClassDescription("Get the weather in a given location")
static class GetWeather implements Supplier<String> {
    @JsonPropertyDescription("The city and state, e.g. San Francisco, CA")
    public String location;

    @Override
    public String get() {
        return "The weather in " + location + " is sunny and 72°F";
    }
}

BetaToolRunner toolRunner = client.beta().messages().toolRunner(
    MessageCreateParams.builder()
        .model("{\{OPUS_ID}\}")
        .maxTokens(1024L)
        .putAdditionalHeader("anthropic-beta", "structured-outputs-2025-11-13")
        .addTool(GetWeather.class)
        .addUserMessage("What's the weather in San Francisco?")
        .build());

for (BetaMessage message : toolRunner) {
    System.out.println(message);
}

非 Beta 工具使用 ​

工具使用也可以通过非 beta 的 com.anthropic.models.messages.MessageCreateParams 实现，使用 addTool(Tool) 方法处理手动定义的 JSON 模式，无需 beta 命名空间。beta 命名空间仅用于类注解便利层（@JsonClassDescription、BetaToolRunner）。

手动循环 ​

对于手动工具循环，需要在请求中将工具定义为 JSON 模式，在响应中处理 tool_use 块，发送 tool_result 返回，并循环直到 stop_reason 为 "end_turn"。有关 agentic 循环模式，请参阅共享工具使用概念。

英文原文 / English Original

Claude API — Java ​

Note: The Java SDK supports the Claude API and beta tool use with annotated classes. Agent SDK is not yet available for Java.

Installation ​

Maven:

xml
<dependency>
    <groupId>com.anthropic</groupId>
    <artifactId>anthropic-java</artifactId>
    <version>2.15.0</version>
</dependency>

Gradle:

groovy
implementation("com.anthropic:anthropic-java:2.15.0")

Client Initialization ​

java
import com.anthropic.client.AnthropicClient;
import com.anthropic.client.okhttp.AnthropicOkHttpClient;

// Default (reads ANTHROPIC_API_KEY from environment)
AnthropicClient client = AnthropicOkHttpClient.fromEnv();

// Explicit API key
AnthropicClient client = AnthropicOkHttpClient.builder()
    .apiKey("your-api-key")
    .build();

Basic Message Request ​

java
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.Model;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("What is the capital of France?")
    .build();

Message response = client.messages().create(params);
response.content().stream()
    .flatMap(block -> block.text().stream())
    .forEach(textBlock -> System.out.println(textBlock.text()));

Streaming ​

java
import com.anthropic.core.http.StreamResponse;
import com.anthropic.models.messages.RawMessageStreamEvent;

MessageCreateParams params = MessageCreateParams.builder()
    .model(Model.CLAUDE_OPUS_4_6)
    .maxTokens(1024L)
    .addUserMessage("Write a haiku")
    .build();

try (StreamResponse<RawMessageStreamEvent> streamResponse = client.messages().createStreaming(params)) {
    streamResponse.stream()
        .flatMap(event -> event.contentBlockDelta().stream())
        .flatMap(deltaEvent -> deltaEvent.delta().text().stream())
        .forEach(textDelta -> System.out.print(textDelta.text()));
}

Tool Use (Beta) ​

The Java SDK supports beta tool use with annotated classes. Tool classes implement Supplier<String> for automatic execution via BetaToolRunner.

Tool Runner (automatic loop) ​

java
import com.anthropic.models.beta.messages.MessageCreateParams;
import com.anthropic.models.beta.messages.BetaMessage;
import com.anthropic.helpers.BetaToolRunner;
import com.fasterxml.jackson.annotation.JsonClassDescription;
import com.fasterxml.jackson.annotation.JsonPropertyDescription;
import java.util.function.Supplier;

@JsonClassDescription("Get the weather in a given location")
static class GetWeather implements Supplier<String> {
    @JsonPropertyDescription("The city and state, e.g. San Francisco, CA")
    public String location;

    @Override
    public String get() {
        return "The weather in " + location + " is sunny and 72°F";
    }
}

BetaToolRunner toolRunner = client.beta().messages().toolRunner(
    MessageCreateParams.builder()
        .model("{\{OPUS_ID}\}")
        .maxTokens(1024L)
        .putAdditionalHeader("anthropic-beta", "structured-outputs-2025-11-13")
        .addTool(GetWeather.class)
        .addUserMessage("What's the weather in San Francisco?")
        .build());

for (BetaMessage message : toolRunner) {
    System.out.println(message);
}

Non-Beta Tool Use ​

Tool use is also available through the non-beta com.anthropic.models.messages.MessageCreateParams with addTool(Tool) for manually defined JSON schemas, without needing the beta namespace. The beta namespace is only needed for the class-annotation convenience layer (@JsonClassDescription, BetaToolRunner).

Manual Loop ​

For manual tool loops, define tools as JSON schema in the request, handle tool_use blocks in the response, send tool_result back, and loop until stop_reason is "end_turn". See the shared tool use concepts for the agentic loop pattern.