大模型 API 调用实践指南

2026 年，调用大模型 API 已经成为后端开发的基本功。

流式响应

const response = await fetch("https://api.deepseek.com/chat/completions", {
  method: "POST",
  headers: { "Authorization": "Bearer sk-xxx" },
  body: JSON.stringify({
    model: "deepseek-chat",
    messages: [{ role: "user", content: "写一首诗" }],
    stream: true,
  }),
});
const reader = response.body.getReader();
const decoder = new TextDecoder();
while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  process.stdout.write(decoder.decode(value));
}

函数调用（Tools）

const response = await fetch("https://api.deepseek.com/v1/chat/completions", {
  method: "POST",
  headers: { "Authorization": "Bearer sk-xxx" },
  body: JSON.stringify({
    model: "deepseek-chat",
    messages: [{ role: "user", content: "北京今天多少度？" }],
    tools: [{
      type: "function",
      function: {
        name: "get_weather",
        description: "获取天气信息",
        parameters: {
          type: "object",
          properties: { city: { type: "string" } },
          required: ["city"],
        },
      },
    }],
  }),
});

掌握大模型 API 调用在 2026 年就像当年掌握 REST API 一样重要。