JavaScript中正确获取并处理API返回的二进制数据（如ZIP文件）教程

/**
 * 将ArrayBuffer转换为Base64字符串。
 * @param buffer 要转换的ArrayBuffer对象。
 * @returns Base64编码的字符串。
 */
function arrayBufferToBase64(buffer: ArrayBuffer): string {
    let binary = '';
    // 创建一个Uint8Array视图来访问ArrayBuffer的字节
    const bytes = new Uint8Array(buffer);
    const len = bytes.byteLength;
    // 遍历所有字节，将其转换为字符并拼接
    for (let i = 0; i < len; i += 1) {
        binary += String.fromCharCode(bytes[i]);
    }
    // 使用btoa函数进行Base64编码
    return btoa(binary);
}

import { Context, Next } from 'koa'; // 假设在Koa环境中使用

// 辅助函数：生成随机整数
function getRandomInt(max: number): number {
    return Math.floor(Math.random() * max);
}

// 将ArrayBuffer转换为Base64字符串的函数
function arrayBufferToBase64(buffer: ArrayBuffer): string {
    let binary = '';
    const bytes = new Uint8Array(buffer);
    const len = bytes.byteLength;
    for (let i = 0; i < len; i += 1) {
        binary += String.fromCharCode(bytes[i]);
    }
    return btoa(binary);
}

// 示例Koa路由处理器
async function handleImageGeneration(ctx: Context, next: Next) {
    const accessToken = 'YOUR_ACCESS_TOKEN'; // 替换为你的实际访问令牌
    const queryparse = { data: { input: 'a beautiful landscape' } }; // 示例输入
    const model = 'nai-diffusion-3'; // 示例模型名称

    try {
        const response = await fetch("https://api.novelai.net/ai/generate-image", {
            method: "POST",
            headers: {
                'Content-Type': 'application/json',
                'Authorization': `Bearer ${accessToken}`,
                'Accept': "*/*" // 接受所有类型的响应
            },
            body: JSON.stringify({
                "input": `masterpiece, best quality, ${queryparse.data.input}`,
                "model": model,
                "action": "generate",
                "parameters": {
                    "width": 768,
                    "height": 512,
                    "scale": 11,
                    "sampler": "k_dpmpp_2m",
                    "steps": 28,
                    "seed": getRandomInt(10000000000),
                    "n_samples": 1,
                    "ucPreset": 0,
                    "qualityToggle": true,
                    "sm": false,
                    "sm_dyn": false,
                    "dynamic_thresholding": false,
                    "controlnet_strength": 1,
                    "legacy": false,
                    "add_original_image": false,
                    "negative_prompt": "lowres, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry"
                }
            })
        });

        // 设置响应状态码
        ctx.status = response.status;

        if (response.ok) {
            // 关键步骤：使用 arrayBuffer() 获取原始二进制数据
            const arrayBuffer = await response.arrayBuffer();
            // 将 ArrayBuffer 转换为 Base64 字符串
            ctx.body = arrayBufferToBase64(arrayBuffer);
            // 提示：NovelAI API返回的ZIP文件通常名为 images.zip，内部包含 image_0.png
        } else {
            // 处理非成功响应，例如错误信息
            const errorText = await response.text();
            ctx.body = `Error: ${response.status} - ${errorText}`;
            console.error(`API Error: ${response.status} - ${errorText}`);
        }
    } catch (error) {
        ctx.status = 500;
        ctx.body = `Internal Server Error: ${error.message}`;
        console.error('Fetch operation failed:', error);
    }

    await next(); // 继续Koa的中间件链
}

// 示例用法 (在实际应用中，这会是一个路由定义)
// app.use(handleImageGeneration);