如何基于已实现的HTTP Get/Post代码编写Delete、Put请求？

Hey there! Let's walk through how to adapt your existing POST code to handle DELETE and PUT requests, with a focus on the ID-based deletion you need.

Adjusting POST Code to DELETE (ID-Based Deletion) #

First, let's cover the key changes you'll need to make, plus important considerations for missing pieces:

Core Modifications #

1. Change the HTTP Request Method
   Swap out the POST method with DELETE in your code. For example, if you're using HttpURLConnection, update conn.setRequestMethod("POST") to conn.setRequestMethod("DELETE"). If you're using a library like OkHttp, adjust the request method to DELETE.

2. Pass the Target ID Correctly
   RESTful best practice for deletion is to embed the ID directly in the URL path (e.g., /api/your-resource/16 instead of sending it in the request body). So instead of your original POST URL (like /api/your-resource), modify it to include the ID:

   // Original POST URL
   URL url = new URL("https://your-api-domain/api/your-resource");
   // Modified DELETE URL with ID
   URL url = new URL("https://your-api-domain/api/your-resource/16");
   

   If your backend expects the ID as a query parameter (e.g., /api/your-resource?id=16), adjust the URL accordingly instead.

3. Remove Request Body Logic
   Unlike POST, DELETE requests rarely require a request body (most REST APIs follow this convention). So you can remove all code that writes data to the request output stream. For HttpURLConnection, this means skipping conn.setDoOutput(true) (or setting it to false), and removing the OutputStream writing block.

Missing Pieces & Considerations #

• Backend Interface Confirmation: Double-check your API docs to confirm how the ID should be passed (path param, query param, or request body—though request body for DELETE is non-standard).
• Response Handling: DELETE has specific HTTP status codes you should handle:
  • 204 No Content: Success (no response body returned)
  • 404 Not Found: The resource with ID 16 doesn't exist
  • 403 Forbidden: You don't have permission to delete the resource
• Request Headers: Ensure you're carrying over any required headers from your POST request (like Authorization tokens, Content-Type, etc.)—these are often needed for authentication/validation.
• Error Handling: Add logic to catch network exceptions, timeouts, or unexpected response codes to make your code robust.

Example Modified DELETE Code (Java HttpURLConnection)

If your original POST code looks like this:

URL url = new URL("https://your-api-domain/api/your-resource");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setDoOutput(true);

// Write POST body
String jsonBody = "{\"name\": \"test\", \"desc\": \"test\", ...}";
try (OutputStream os = conn.getOutputStream()) {
    byte[] input = jsonBody.getBytes("utf-8");
    os.write(input, 0, input.length);
}

// Handle response
int responseCode = conn.getResponseCode();
// ... rest of response handling

Your modified DELETE code would be:

URL url = new URL("https://your-api-domain/api/your-resource/16");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("DELETE");
conn.setRequestProperty("Authorization", "Bearer your-token"); // Keep required headers
conn.setDoOutput(false); // No request body needed

// Handle response
int responseCode = conn.getResponseCode();
switch(responseCode) {
    case HttpURLConnection.HTTP_NO_CONTENT:
        System.out.println("Resource with ID 16 deleted successfully");
        break;
    case HttpURLConnection.HTTP_NOT_FOUND:
        System.out.println("Resource with ID 16 does not exist");
        break;
    default:
        System.out.println("Delete failed with code: " + responseCode);
}

Adjusting POST Code to PUT Requests #

PUT is used to update an existing resource (often ID-based, similar to DELETE). Here's what to change:

Core Modifications #

1. Change the HTTP Method to PUT
   Update the request method from POST to PUT (same way you did for DELETE).

2. Embed the Target ID in the URL
   Just like DELETE, include the resource ID in the URL path (e.g., /api/your-resource/16) to specify which resource to update.

3. Keep (or Adjust) the Request Body
   Unlike DELETE, PUT requires a request body with the updated resource data (the name, desc, reward, etc. parameters you provided). You can reuse most of your POST body-writing logic, but update the JSON payload to reflect the new values you want to set.

Key Notes #

• Idempotency: PUT is designed to be idempotent—sending the same request multiple times should have the same effect (unlike POST). Ensure your payload reflects the full state of the resource (or check if your API supports partial updates with PATCH instead).
• Response Status Codes: Watch for 200 OK (update successful), 201 Created (if the ID didn't exist and the API created it), or 404 Not Found (resource doesn't exist).

Example PUT Code Snippet

URL url = new URL("https://your-api-domain/api/your-resource/16");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("PUT");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Authorization", "Bearer your-token");
conn.setDoOutput(true);

// Write updated resource data
String updatedJsonBody = "{\"name\": \"updated-test\", \"desc\": \"updated-desc\", \"reward\":\"2.00\", \"sched\":\"2018-04-05T11:49:51+08:00\"}";
try (OutputStream os = conn.getOutputStream()) {
    byte[] input = updatedJsonBody.getBytes("utf-8");
    os.write(input, 0, input.length);
}

// Handle response
int responseCode = conn.getResponseCode();
if(responseCode == HttpURLConnection.HTTP_OK) {
    System.out.println("Resource updated successfully");
} else if(responseCode == HttpURLConnection.HTTP_NOT_FOUND) {
    System.out.println("Resource with ID 16 not found");
}

内容的提问来源于stack exchange，提问作者user9551058