基本的llm应用

import os

from langchain_core.prompts import ChatPromptTemplate

from langchain_core.output_parsers import StrOutputParser

from langchain_openai import ChatOpenAI

os.environ["OPENAI_API_KEY"] = "sk-..." # 或通过环境变量配置

# 1. Prompt

prompt = ChatPromptTemplate.from_messages([

("system", "你是一位资深的{role},请用简洁的中文回答。"),

("user", "{question}"),

])

# 2. Model

model = ChatOpenAI(model="gpt-4o-mini", temperature=0)

# 3. Parser

parser = StrOutputParser()

# 用 | 组合成链 (LCEL)

chain = prompt | model | parser

result = chain.invoke({

"role": "Python 工程师",

"question": "什么是装饰器?用一句话回答。",

})

print(result)