Node.js AI 开发实战

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一、环境准备

安装 Node.js

访问 Node.js 官网 下载 LTS 版本。

创建项目

mkdir ai-app
cd ai-app
npm init -y
npm install express openai

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二、基础 API 调用

OpenAI SDK

import OpenAI from 'openai';
const client = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY
});
async function chat(message) {
  const response = await client.chat.completions.create({
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: message }]
  });
  return response.choices[0].message.content;
}

流式输出

async function chatStream(message) {
  const stream = await client.chat.completions.create({
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: message }],
    stream: true
  });
  
  for await (const chunk of stream) {
    process.stdout.write(chunk.choices[0].delta.content || '');
  }
}

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三、构建 API 服务

Express 服务

import express from 'express';
const app = express();
app.use(express.json());
app.post('/chat', async (req, res) => {
  const { message } = req.body;
  const reply = await chat(message);
  res.json({ reply });
});
app.listen(3000, () => {
  console.log('AI API running on port 3000');
});

流式 API

app.post('/chat/stream', async (req, res) => {
  res.setHeader('Content-Type', 'text/event-stream');
  
  const stream = await client.chat.completions.create({
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: req.body.message }],
    stream: true
  });
  
  for await (const chunk of stream) {
    res.write(data: ${JSON.stringify(chunk)}\n\n);
  }
  
  res.end();
});

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四、实战案例

1. 文档问答

async function answerQuestion(doc, question) {
  const response = await client.chat.completions.create({
    model: 'gpt-4o-mini',
    messages: [
      { role: 'system', content: 参考文档：${doc} },
      { role: 'user', content: question }
    ]
  });
  return response.choices[0].message.content;
}

2. 图片分析

async function analyzeImage(imageUrl, question) {
  const response = await client.chat.completions.create({
    model: 'gpt-4o',
    messages: [{
      role: 'user',
      content: [
        { type: 'text', text: question },
        { type: 'image_url', image_url: { url: imageUrl } }
      ]
    }]
  });
  return response.choices[0].message.content;
}

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五、部署

PM2 部署

npm install -g pm2
pm2 start app.js --name ai-api
pm2 save
pm2 startup

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