Nano Banana API：Gemini 图像模型总览与接入

{
  "candidates": [{
    "content": {
      "role": "model",
      "parts": [
        {"inlineData": {"mimeType": "image/png", "data": "iVBORw0KGgo..."}}
      ]
    },
    "finishReason": "STOP"
  }]
}

export LAOZHANG_API_KEY="替换为你的老张API密钥"
python -m pip install requests

"""Nano Banana 共用函数：发送请求、读取本地图片、保存返回的图片。"""
import base64
import json
import os
import re
import sys
from pathlib import Path

import requests

API_BASE = "https://api.laozhang.ai"
MIME_TYPES = {".png": "image/png", ".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".webp": "image/webp"}
EXTENSIONS = {"png": "png", "jpeg": "jpg", "jpg": "jpg", "webp": "webp"}


def post(path, payload):
    """发送 JSON 请求；HTTP 状态不是 200 时显示错误正文并退出。"""
    response = requests.post(
        API_BASE + path,
        headers={"Authorization": f"Bearer {os.environ['LAOZHANG_API_KEY']}"},
        json=payload,
        timeout=300,
    )
    if response.status_code != 200:
        raise SystemExit(f"HTTP {response.status_code}：{response.text[:1000]}")
    return response.json()


def read_image(path):
    """读取本地 PNG、JPEG 或 WebP 图片，返回 (MIME 类型, Base64 字符串)。"""
    path = Path(path)
    mime = MIME_TYPES.get(path.suffix.lower())
    if mime is None:
        raise SystemExit(f"只支持 PNG、JPEG、WebP 图片：{path}")
    return mime, base64.b64encode(path.read_bytes()).decode("ascii")


def save_images(result, prefix):
    """保存 OpenAI 兼容或 Gemini 原生响应中的全部图片，返回文件名列表。"""
    if "choices" in result:
        # OpenAI 兼容格式：图片是 message.content 里的 data URL
        content = str(result["choices"][0]["message"].get("content") or "")
        images = re.findall(r"data:image/(png|jpe?g|webp);base64,([A-Za-z0-9+/=]+)", content)
    else:
        # Gemini 原生格式：图片在 candidates[].content.parts[].inlineData 中
        images = [
            (part["inlineData"]["mimeType"].split("/")[-1], part["inlineData"]["data"])
            for candidate in result.get("candidates") or []
            for part in (candidate.get("content") or {}).get("parts") or []
            if "inlineData" in part and not part.get("thought")
        ]
    if not images:
        raise SystemExit("响应中没有图片：" + json.dumps(result, ensure_ascii=False)[:1000])
    filenames = []
    for index, (kind, data) in enumerate(images, start=1):
        filename = f"{prefix}-{index}.{EXTENSIONS.get(kind, kind)}"
        Path(filename).write_bytes(base64.b64decode(data + "=" * (-len(data) % 4)))
        print("已保存", filename)
        filenames.append(filename)
    return filenames


if __name__ == "__main__":
    if len(sys.argv) != 3:
        raise SystemExit("用法：python nano_banana.py 响应文件.json 输出文件前缀")
    save_images(json.loads(Path(sys.argv[1]).read_text(encoding="utf-8")), sys.argv[2])

from nano_banana import post, read_image, save_images

mime, data = read_image("standard-generate-1.png")  # 替换为你的图片路径

result = post("/v1/chat/completions", {
    "model": "gemini-2.5-flash-image",
    "stream": False,
    "messages": [{
        "role": "user",
        "content": [
            {"type": "text", "text": "把背景换成雪后的松林，保留小木屋的结构和颜色"},
            {"type": "image_url", "image_url": {"url": f"data:{mime};base64,{data}"}},
        ],
    }],
})
save_images(result, "standard-edit")

{
  "contents": [{
    "role": "user",
    "parts": [
      {"text": "让第一张图中的人物穿上第二张图里的外套"},
      {"fileData": {"mimeType": "image/jpeg", "fileUri": "https://cdn.example.com/person.jpg"}},
      {"inlineData": {"mimeType": "image/png", "data": "<外套图片的 Base64 数据>"}}
    ]
  }],
  "generationConfig": {"responseModalities": ["IMAGE"]}
}