AstrBot/astrbot/core/provider/sources/gemini_source.py

import asyncio
import base64
import json
import logging
import random
from collections.abc import AsyncGenerator
from typing import cast

from google import genai
from google.genai import types
from google.genai.errors import APIError

import astrbot.core.message.components as Comp
from astrbot import logger
from astrbot.api.provider import Provider
from astrbot.core.message.message_event_result import MessageChain
from astrbot.core.provider.entities import LLMResponse
from astrbot.core.provider.func_tool_manager import ToolSet
from astrbot.core.utils.io import download_image_by_url

from ..register import register_provider_adapter


class SuppressNonTextPartsWarning(logging.Filter):
    """过滤 Gemini SDK 中的非文本部分警告"""

    def filter(self, record):
        return "there are non-text parts in the response" not in record.getMessage()


logging.getLogger("google_genai.types").addFilter(SuppressNonTextPartsWarning())


@register_provider_adapter(
    "googlegenai_chat_completion",
    "Google Gemini Chat Completion 提供商适配器",
)
class ProviderGoogleGenAI(Provider):
    CATEGORY_MAPPING = {
        "harassment": types.HarmCategory.HARM_CATEGORY_HARASSMENT,
        "hate_speech": types.HarmCategory.HARM_CATEGORY_HATE_SPEECH,
        "sexually_explicit": types.HarmCategory.HARM_CATEGORY_SEXUALLY_EXPLICIT,
        "dangerous_content": types.HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
    }

    THRESHOLD_MAPPING = {
        "BLOCK_NONE": types.HarmBlockThreshold.BLOCK_NONE,
        "BLOCK_ONLY_HIGH": types.HarmBlockThreshold.BLOCK_ONLY_HIGH,
        "BLOCK_MEDIUM_AND_ABOVE": types.HarmBlockThreshold.BLOCK_MEDIUM_AND_ABOVE,
        "BLOCK_LOW_AND_ABOVE": types.HarmBlockThreshold.BLOCK_LOW_AND_ABOVE,
    }

    def __init__(
        self,
        provider_config,
        provider_settings,
    ) -> None:
        super().__init__(
            provider_config,
            provider_settings,
        )
        self.api_keys: list = super().get_keys()
        self.chosen_api_key: str = self.api_keys[0] if len(self.api_keys) > 0 else ""
        self.timeout: int = int(provider_config.get("timeout", 180))

        self.api_base: str | None = provider_config.get("api_base", None)
        if self.api_base and self.api_base.endswith("/"):
            self.api_base = self.api_base[:-1]

        self._init_client()
        self.set_model(provider_config["model_config"]["model"])
        self._init_safety_settings()

    def _init_client(self) -> None:
        """初始化Gemini客户端"""
        self.client = genai.Client(
            api_key=self.chosen_api_key,
            http_options=types.HttpOptions(
                base_url=self.api_base,
                timeout=self.timeout * 1000,  # 毫秒
            ),
        ).aio

    def _init_safety_settings(self) -> None:
        """初始化安全设置"""
        user_safety_config = self.provider_config.get("gm_safety_settings", {})
        self.safety_settings = [
            types.SafetySetting(
                category=harm_category,
                threshold=self.THRESHOLD_MAPPING[threshold_str],
            )
            for config_key, harm_category in self.CATEGORY_MAPPING.items()
            if (threshold_str := user_safety_config.get(config_key))
            and threshold_str in self.THRESHOLD_MAPPING
        ]

    async def _handle_api_error(self, e: APIError, keys: list[str]) -> bool:
        """处理API错误，返回是否需要重试"""
        if e.message is None:
            e.message = ""

        if e.code == 429 or "API key not valid" in e.message:
            keys.remove(self.chosen_api_key)
            if len(keys) > 0:
                self.set_key(random.choice(keys))
                logger.info(
                    f"检测到 Key 异常({e.message})，正在尝试更换 API Key 重试... 当前 Key: {self.chosen_api_key[:12]}...",
                )
                await asyncio.sleep(1)
                return True
            logger.error(
                f"检测到 Key 异常({e.message})，且已没有可用的 Key。 当前 Key: {self.chosen_api_key[:12]}...",
            )
            raise Exception("达到了 Gemini 速率限制, 请稍后再试...")
        # logger.error(
        #     f"发生了错误(gemini_source)。Provider 配置如下: {self.provider_config}",
        # )
        raise e

    async def _prepare_query_config(
        self,
        payloads: dict,
        tools: ToolSet | None = None,
        system_instruction: str | None = None,
        modalities: list[str] | None = None,
        temperature: float = 0.7,
    ) -> types.GenerateContentConfig:
        """准备查询配置"""
        if not modalities:
            modalities = ["Text"]

        # 流式输出不支持图片模态
        if (
            self.provider_settings.get("streaming_response", False)
            and "Image" in modalities
        ):
            logger.warning("流式输出不支持图片模态，已自动降级为文本模态")
            modalities = ["Text"]

        tool_list: list[types.Tool] | None = []
        model_name = self.get_model()
        native_coderunner = self.provider_config.get("gm_native_coderunner", False)
        native_search = self.provider_config.get("gm_native_search", False)
        url_context = self.provider_config.get("gm_url_context", False)

        if "gemini-2.5" in model_name:
            if native_coderunner:
                tool_list.append(types.Tool(code_execution=types.ToolCodeExecution()))
                if native_search:
                    logger.warning("代码执行工具与搜索工具互斥，已忽略搜索工具")
                if url_context:
                    logger.warning(
                        "代码执行工具与URL上下文工具互斥，已忽略URL上下文工具",
                    )
            else:
                if native_search:
                    tool_list.append(types.Tool(google_search=types.GoogleSearch()))

                if url_context:
                    if hasattr(types, "UrlContext"):
                        tool_list.append(types.Tool(url_context=types.UrlContext()))
                    else:
                        logger.warning(
                            "当前 SDK 版本不支持 URL 上下文工具，已忽略该设置，请升级 google-genai 包",
                        )

        elif "gemini-2.0-lite" in model_name:
            if native_coderunner or native_search or url_context:
                logger.warning(
                    "gemini-2.0-lite 不支持代码执行、搜索工具和URL上下文，将忽略这些设置",
                )
            tool_list = None

        else:
            if native_coderunner:
                tool_list.append(types.Tool(code_execution=types.ToolCodeExecution()))
                if native_search:
                    logger.warning("代码执行工具与搜索工具互斥，已忽略搜索工具")
            elif native_search:
                tool_list.append(types.Tool(google_search=types.GoogleSearch()))

            if url_context and not native_coderunner:
                if hasattr(types, "UrlContext"):
                    tool_list.append(types.Tool(url_context=types.UrlContext()))
                else:
                    logger.warning(
                        "当前 SDK 版本不支持 URL 上下文工具，已忽略该设置，请升级 google-genai 包",
                    )

        if not tool_list:
            tool_list = None

        if tools and tool_list:
            logger.warning("已启用原生工具，函数工具将被忽略")
        elif tools and (func_desc := tools.get_func_desc_google_genai_style()):
            tool_list = [
                types.Tool(function_declarations=func_desc["function_declarations"]),
            ]

        return types.GenerateContentConfig(
            system_instruction=system_instruction,
            temperature=temperature,
            max_output_tokens=payloads.get("max_tokens")
            or payloads.get("maxOutputTokens"),
            top_p=payloads.get("top_p") or payloads.get("topP"),
            top_k=payloads.get("top_k") or payloads.get("topK"),
            frequency_penalty=payloads.get("frequency_penalty")
            or payloads.get("frequencyPenalty"),
            presence_penalty=payloads.get("presence_penalty")
            or payloads.get("presencePenalty"),
            stop_sequences=payloads.get("stop") or payloads.get("stopSequences"),
            response_logprobs=payloads.get("response_logprobs")
            or payloads.get("responseLogprobs"),
            logprobs=payloads.get("logprobs"),
            seed=payloads.get("seed"),
            response_modalities=modalities,
            tools=cast(types.ToolListUnion | None, tool_list),
            safety_settings=self.safety_settings if self.safety_settings else None,
            thinking_config=(
                types.ThinkingConfig(
                    thinking_budget=min(
                        int(
                            self.provider_config.get("gm_thinking_config", {}).get(
                                "budget",
                                0,
                            ),
                        ),
                        24576,
                    ),
                )
                if "gemini-2.5-flash" in self.get_model()
                and hasattr(types.ThinkingConfig, "thinking_budget")
                else None
            ),
            automatic_function_calling=types.AutomaticFunctionCallingConfig(
                disable=True,
            ),
        )

    def _prepare_conversation(self, payloads: dict) -> list[types.Content]:
        """准备 Gemini SDK 的 Content 列表"""

        def create_text_part(text: str) -> types.Part:
            content_a = text if text else " "
            if not text:
                logger.warning("文本内容为空，已添加空格占位")
            return types.Part.from_text(text=content_a)

        def process_image_url(image_url_dict: dict) -> types.Part:
            url = image_url_dict["url"]
            mime_type = url.split(":")[1].split(";")[0]
            image_bytes = base64.b64decode(url.split(",", 1)[1])
            return types.Part.from_bytes(data=image_bytes, mime_type=mime_type)

        def append_or_extend(
            contents: list[types.Content],
            part: list[types.Part],
            content_cls: type[types.Content],
        ) -> None:
            if contents and isinstance(contents[-1], content_cls):
                assert contents[-1].parts is not None
                contents[-1].parts.extend(part)
            else:
                contents.append(content_cls(parts=part))

        gemini_contents: list[types.Content] = []
        native_tool_enabled = any(
            [
                self.provider_config.get("gm_native_coderunner", False),
                self.provider_config.get("gm_native_search", False),
            ],
        )
        for message in payloads["messages"]:
            role, content = message["role"], message.get("content")

            if role == "user":
                if isinstance(content, list):
                    parts = [
                        (
                            types.Part.from_text(text=item["text"] or " ")
                            if item["type"] == "text"
                            else process_image_url(item["image_url"])
                        )
                        for item in content
                    ]
                else:
                    parts = [create_text_part(content)]
                append_or_extend(gemini_contents, parts, types.UserContent)

            elif role == "assistant":
                if content:
                    parts = [types.Part.from_text(text=content)]
                    append_or_extend(gemini_contents, parts, types.ModelContent)
                elif not native_tool_enabled and "tool_calls" in message:
                    parts = []
                    for tool in message["tool_calls"]:
                        part = types.Part.from_function_call(
                            name=tool["function"]["name"],
                            args=json.loads(tool["function"]["arguments"]),
                        )
                        # we should set thought_signature back to part if exists
                        # for more info about thought_signature, see:
                        # https://ai.google.dev/gemini-api/docs/thought-signatures
                        if "extra_content" in tool and tool["extra_content"]:
                            ts_bs64 = (
                                tool["extra_content"]
                                .get("google", {})
                                .get("thought_signature")
                            )
                            if ts_bs64:
                                part.thought_signature = base64.b64decode(ts_bs64)
                        parts.append(part)
                    append_or_extend(gemini_contents, parts, types.ModelContent)
                else:
                    logger.warning("assistant 角色的消息内容为空，已添加空格占位")
                    if native_tool_enabled and "tool_calls" in message:
                        logger.warning(
                            "检测到启用Gemini原生工具，且上下文中存在函数调用，建议使用 /reset 重置上下文",
                        )
                    parts = [types.Part.from_text(text=" ")]
                    append_or_extend(gemini_contents, parts, types.ModelContent)

            elif role == "tool" and not native_tool_enabled:
                parts = [
                    types.Part.from_function_response(
                        name=message["tool_call_id"],
                        response={
                            "name": message["tool_call_id"],
                            "content": message["content"],
                        },
                    ),
                ]
                append_or_extend(gemini_contents, parts, types.UserContent)

        if gemini_contents and isinstance(gemini_contents[0], types.ModelContent):
            gemini_contents.pop()

        return gemini_contents

    def _extract_reasoning_content(self, candidate: types.Candidate) -> str:
        """Extract reasoning content from candidate parts"""
        if not candidate.content or not candidate.content.parts:
            return ""

        thought_buf: list[str] = [
            (p.text or "") for p in candidate.content.parts if p.thought
        ]
        return "".join(thought_buf).strip()

    def _process_content_parts(
        self,
        candidate: types.Candidate,
        llm_response: LLMResponse,
    ) -> MessageChain:
        """处理内容部分并构建消息链"""
        if not candidate.content:
            logger.warning(f"收到的 candidate.content 为空: {candidate}")
            raise Exception("API 返回的 candidate.content 为空。")

        finish_reason = candidate.finish_reason
        result_parts: list[types.Part] | None = candidate.content.parts

        if finish_reason == types.FinishReason.SAFETY:
            raise Exception("模型生成内容未通过 Gemini 平台的安全检查")

        if finish_reason in {
            types.FinishReason.PROHIBITED_CONTENT,
            types.FinishReason.SPII,
            types.FinishReason.BLOCKLIST,
        }:
            raise Exception("模型生成内容违反 Gemini 平台政策")

        # 防止旧版本SDK不存在IMAGE_SAFETY
        if hasattr(types.FinishReason, "IMAGE_SAFETY"):
            if finish_reason == types.FinishReason.IMAGE_SAFETY:
                raise Exception("模型生成内容违反 Gemini 平台政策")

        if not result_parts:
            logger.warning(f"收到的 candidate.content.parts 为空: {candidate}")
            raise Exception("API 返回的 candidate.content.parts 为空。")

        # 提取 reasoning content
        reasoning = self._extract_reasoning_content(candidate)
        if reasoning:
            llm_response.reasoning_content = reasoning

        chain = []
        part: types.Part

        # 暂时这样Fallback
        if all(
            part.inline_data
            and part.inline_data.mime_type
            and part.inline_data.mime_type.startswith("image/")
            for part in result_parts
        ):
            chain.append(Comp.Plain("这是图片"))
        for part in result_parts:
            if part.text:
                chain.append(Comp.Plain(part.text))
            elif (
                part.function_call
                and part.function_call.name is not None
                and part.function_call.args is not None
            ):
                llm_response.role = "tool"
                llm_response.tools_call_name.append(part.function_call.name)
                llm_response.tools_call_args.append(part.function_call.args)
                # function_call.id might be None, use name as fallback
                tool_call_id = part.function_call.id or part.function_call.name
                llm_response.tools_call_ids.append(tool_call_id)
                # extra_content
                if part.thought_signature:
                    ts_bs64 = base64.b64encode(part.thought_signature).decode("utf-8")
                    llm_response.tools_call_extra_content[tool_call_id] = {
                        "google": {"thought_signature": ts_bs64}
                    }
            elif (
                part.inline_data
                and part.inline_data.mime_type
                and part.inline_data.mime_type.startswith("image/")
                and part.inline_data.data
            ):
                chain.append(Comp.Image.fromBytes(part.inline_data.data))
        return MessageChain(chain=chain)

    async def _query(self, payloads: dict, tools: ToolSet | None) -> LLMResponse:
        """非流式请求 Gemini API"""
        system_instruction = next(
            (msg["content"] for msg in payloads["messages"] if msg["role"] == "system"),
            None,
        )

        modalities = ["Text"]
        if self.provider_config.get("gm_resp_image_modal", False):
            modalities.append("Image")

        conversation = self._prepare_conversation(payloads)
        temperature = payloads.get("temperature", 0.7)

        result: types.GenerateContentResponse | None = None
        while True:
            try:
                config = await self._prepare_query_config(
                    payloads,
                    tools,
                    system_instruction,
                    modalities,
                    temperature,
                )
                result = await self.client.models.generate_content(
                    model=self.get_model(),
                    contents=cast(types.ContentListUnion, conversation),
                    config=config,
                )
                logger.debug(f"genai result: {result}")

                if not result.candidates:
                    logger.error(f"请求失败, 返回的 candidates 为空: {result}")
                    raise Exception("请求失败, 返回的 candidates 为空。")

                if result.candidates[0].finish_reason == types.FinishReason.RECITATION:
                    if temperature > 2:
                        raise Exception("温度参数已超过最大值2，仍然发生recitation")
                    temperature += 0.2
                    logger.warning(
                        f"发生了recitation，正在提高温度至{temperature:.1f}重试...",
                    )
                    continue

                break

            except APIError as e:
                if e.message is None:
                    e.message = ""
                if "Developer instruction is not enabled" in e.message:
                    logger.warning(
                        f"{self.get_model()} 不支持 system prompt，已自动去除(影响人格设置)",
                    )
                    system_instruction = None
                elif "Function calling is not enabled" in e.message:
                    logger.warning(f"{self.get_model()} 不支持函数调用，已自动去除")
                    tools = None
                elif (
                    "Multi-modal output is not supported" in e.message
                    or "Model does not support the requested response modalities"
                    in e.message
                    or "only supports text output" in e.message
                ):
                    logger.warning(
                        f"{self.get_model()} 不支持多模态输出，降级为文本模态",
                    )
                    modalities = ["Text"]
                else:
                    raise
                continue

        llm_response = LLMResponse("assistant")
        llm_response.raw_completion = result
        llm_response.result_chain = self._process_content_parts(
            result.candidates[0],
            llm_response,
        )
        return llm_response

    async def _query_stream(
        self,
        payloads: dict,
        tools: ToolSet | None,
    ) -> AsyncGenerator[LLMResponse, None]:
        """流式请求 Gemini API"""
        system_instruction = next(
            (msg["content"] for msg in payloads["messages"] if msg["role"] == "system"),
            None,
        )

        conversation = self._prepare_conversation(payloads)

        result = None
        while True:
            try:
                config = await self._prepare_query_config(
                    payloads,
                    tools,
                    system_instruction,
                )
                result = await self.client.models.generate_content_stream(
                    model=self.get_model(),
                    contents=cast(types.ContentListUnion, conversation),
                    config=config,
                )
                break
            except APIError as e:
                if e.message is None:
                    e.message = ""
                if "Developer instruction is not enabled" in e.message:
                    logger.warning(
                        f"{self.get_model()} 不支持 system prompt，已自动去除(影响人格设置)",
                    )
                    system_instruction = None
                elif "Function calling is not enabled" in e.message:
                    logger.warning(f"{self.get_model()} 不支持函数调用，已自动去除")
                    tools = None
                else:
                    raise
                continue

        # Accumulate the complete response text for the final response
        accumulated_text = ""
        accumulated_reasoning = ""
        final_response = None

        async for chunk in result:
            llm_response = LLMResponse("assistant", is_chunk=True)

            if not chunk.candidates:
                logger.warning(f"收到的 chunk 中 candidates 为空: {chunk}")
                continue
            if not chunk.candidates[0].content:
                logger.warning(f"收到的 chunk 中 content 为空: {chunk}")
                continue

            if chunk.candidates[0].content.parts and any(
                part.function_call for part in chunk.candidates[0].content.parts
            ):
                llm_response = LLMResponse("assistant", is_chunk=False)
                llm_response.raw_completion = chunk
                llm_response.result_chain = self._process_content_parts(
                    chunk.candidates[0],
                    llm_response,
                )
                yield llm_response
                return

            _f = False

            # 提取 reasoning content
            reasoning = self._extract_reasoning_content(chunk.candidates[0])
            if reasoning:
                _f = True
                accumulated_reasoning += reasoning
                llm_response.reasoning_content = reasoning
            if chunk.text:
                _f = True
                accumulated_text += chunk.text
                llm_response.result_chain = MessageChain(chain=[Comp.Plain(chunk.text)])
            if _f:
                yield llm_response

            if chunk.candidates[0].finish_reason:
                # Process the final chunk for potential tool calls or other content
                if chunk.candidates[0].content.parts:
                    final_response = LLMResponse("assistant", is_chunk=False)
                    final_response.raw_completion = chunk
                    final_response.result_chain = self._process_content_parts(
                        chunk.candidates[0],
                        final_response,
                    )
                break

        # Yield final complete response with accumulated text
        if not final_response:
            final_response = LLMResponse("assistant", is_chunk=False)

        # Set the complete accumulated reasoning in the final response
        if accumulated_reasoning:
            final_response.reasoning_content = accumulated_reasoning

        # Set the complete accumulated text in the final response
        if accumulated_text:
            final_response.result_chain = MessageChain(
                chain=[Comp.Plain(accumulated_text)],
            )
        elif not final_response.result_chain:
            # If no text was accumulated and no final response was set, provide empty space
            final_response.result_chain = MessageChain(chain=[Comp.Plain(" ")])

        yield final_response

    async def text_chat(
        self,
        prompt=None,
        session_id=None,
        image_urls=None,
        func_tool=None,
        contexts=None,
        system_prompt=None,
        tool_calls_result=None,
        model=None,
        **kwargs,
    ) -> LLMResponse:
        if contexts is None:
            contexts = []
        new_record = None
        if prompt is not None:
            new_record = await self.assemble_context(prompt, image_urls)
        context_query = self._ensure_message_to_dicts(contexts)
        if new_record:
            context_query.append(new_record)
        if system_prompt:
            context_query.insert(0, {"role": "system", "content": system_prompt})

        for part in context_query:
            if "_no_save" in part:
                del part["_no_save"]

        # tool calls result
        if tool_calls_result:
            if not isinstance(tool_calls_result, list):
                context_query.extend(tool_calls_result.to_openai_messages())
            else:
                for tcr in tool_calls_result:
                    context_query.extend(tcr.to_openai_messages())

        model_config = self.provider_config.get("model_config", {})
        model_config["model"] = model or self.get_model()

        payloads = {"messages": context_query, **model_config}

        retry = 10
        keys = self.api_keys.copy()

        for _ in range(retry):
            try:
                return await self._query(payloads, func_tool)
            except APIError as e:
                if await self._handle_api_error(e, keys):
                    continue
                break

        raise Exception("请求失败。")

    async def text_chat_stream(
        self,
        prompt=None,
        session_id=None,
        image_urls=None,
        func_tool=None,
        contexts=None,
        system_prompt=None,
        tool_calls_result=None,
        model=None,
        **kwargs,
    ) -> AsyncGenerator[LLMResponse, None]:
        if contexts is None:
            contexts = []
        new_record = None
        if prompt is not None:
            new_record = await self.assemble_context(prompt, image_urls)
        context_query = self._ensure_message_to_dicts(contexts)
        if new_record:
            context_query.append(new_record)
        if system_prompt:
            context_query.insert(0, {"role": "system", "content": system_prompt})

        for part in context_query:
            if "_no_save" in part:
                del part["_no_save"]

        # tool calls result
        if tool_calls_result:
            if not isinstance(tool_calls_result, list):
                context_query.extend(tool_calls_result.to_openai_messages())
            else:
                for tcr in tool_calls_result:
                    context_query.extend(tcr.to_openai_messages())

        model_config = self.provider_config.get("model_config", {})
        model_config["model"] = model or self.get_model()

        payloads = {"messages": context_query, **model_config}

        retry = 10
        keys = self.api_keys.copy()

        for _ in range(retry):
            try:
                async for response in self._query_stream(payloads, func_tool):
                    yield response
                break
            except APIError as e:
                if await self._handle_api_error(e, keys):
                    continue
                break

    async def get_models(self):
        try:
            models = await self.client.models.list()
            return [
                m.name.replace("models/", "")
                for m in models
                if m.supported_actions
                and "generateContent" in m.supported_actions
                and m.name
            ]
        except APIError as e:
            raise Exception(f"获取模型列表失败: {e.message}")

    def get_current_key(self) -> str:
        return self.chosen_api_key

    def get_keys(self) -> list[str]:
        return self.api_keys

    def set_key(self, key):
        self.chosen_api_key = key
        self._init_client()

    async def assemble_context(self, text: str, image_urls: list[str] | None = None):
        """组装上下文。"""
        if image_urls:
            user_content = {
                "role": "user",
                "content": [{"type": "text", "text": text if text else "[图片]"}],
            }
            for image_url in image_urls:
                if image_url.startswith("http"):
                    image_path = await download_image_by_url(image_url)
                    image_data = await self.encode_image_bs64(image_path)
                elif image_url.startswith("file:///"):
                    image_path = image_url.replace("file:///", "")
                    image_data = await self.encode_image_bs64(image_path)
                else:
                    image_data = await self.encode_image_bs64(image_url)
                if not image_data:
                    logger.warning(f"图片 {image_url} 得到的结果为空，将忽略。")
                    continue
                user_content["content"].append(
                    {
                        "type": "image_url",
                        "image_url": {"url": image_data},
                    },
                )
            return user_content
        return {"role": "user", "content": text}

    async def encode_image_bs64(self, image_url: str) -> str:
        """将图片转换为 base64"""
        if image_url.startswith("base64://"):
            return image_url.replace("base64://", "data:image/jpeg;base64,")
        with open(image_url, "rb") as f:
            image_bs64 = base64.b64encode(f.read()).decode("utf-8")
            return "data:image/jpeg;base64," + image_bs64

    async def terminate(self):
        logger.info("Google GenAI 适配器已终止。")