使用Python3.5与Requests下载Openi图片：是否需逐个下载？

Hey there! Let's tackle this question for you.

First off: Yes, you do need to download each image individually — the Openi REST API you're calling only returns metadata (like the .png filenames) rather than providing a bulk download option. But don't worry, we can automate this process with Python so you don't have to do it manually.

Here's a step-by-step solution: #

1. Fetch the image metadata using the retrieve.php endpoint (you already have this part covered)
2. Parse the returned JSON to extract each image's filename
3. Build the direct download URL for each image and save them locally

Full example code #

import requests
import json
import time  # For adding delays if needed

# Fetch metadata for your query
response = requests.get(
    "http://openi.nlm.nih.gov/retrieve.php",
    params={"query": "Feulgen", "m": 1, "n": 12}
)

if response.status_code == 200:
    try:
        image_data = json.loads(response.content)
        # Loop through each image entry in the metadata
        for img_entry in image_data.get("list", []):
            img_filename = img_entry.get("imgFileName")
            if not img_filename:
                print("Skipping entry: No image filename found")
                continue
            
            # Construct the direct image URL
            img_url = f"http://openi.nlm.nih.gov/images/{img_filename}"
            img_response = requests.get(img_url)
            
            if img_response.status_code == 200:
                # Save the image to your local machine
                with open(img_filename, "wb") as img_file:
                    img_file.write(img_response.content)
                print(f"Successfully downloaded: {img_filename}")
                # Optional: Add a small delay to be kind to the server
                time.sleep(0.5)
            else:
                print(f"Failed to download {img_filename}: Status code {img_response.status_code}")
    except json.JSONDecodeError:
        print("Error parsing JSON response from the API")
else:
    print(f"Failed to fetch metadata: Status code {response.status_code}")

A few quick tips: #

• Handle exceptions: The code above includes basic error handling for JSON parsing and missing filenames, but you can expand this to cover network timeouts or other issues
• Respect rate limits: Adding a small delay (like time.sleep(0.5)) between requests helps avoid overwhelming the server and getting your IP blocked
• Customize save paths: Instead of saving to the current directory, you can create a dedicated folder (e.g., ./openi_images/) and save images there — just make sure the folder exists before running the code

内容的提问来源于stack exchange，提问作者MissBleu