Detailed explanation of four HTTP methods (GET, POST, PUT and DELETE)

1. GET and POST

1. GET method

Features：

• use: Used to obtain data from the server.
• Parameter transfer method: The parameter will be appended to the URL to key=valueThe form is passed through query strings, for example:

/page?name=John&age=30

• Visibility: The parameters are plain text, and users can directly see the passed parameters in the browser address bar.
• limit: Due to the URL length limitation (specific restrictions vary by browser and server, but generally around 2,000 characters), the amount of data transmitted is relatively small.
• Idepotency: GET requests are idempotent, and repeatedly sending the same GET request will not change the state of the server.
• cache: The data requested by the GET can be cached by the browser or saved in the browser history.

advantage：

• Simple and intuitive, suitable for obtaining data.
• It can be saved through bookmarks for easy sharing.

shortcoming：

• Parameters are exposed to URLs, and sensitive data (such as passwords) are not secure.
• The amount of data is limited and large data cannot be uploaded.

2. POST method

Features：

• use: Used to submit data to the server, such as form submission or upload files.
• Parameter delivery method: Parameters are contained in the request body (Body), usually implicit. For example:

POST /form HTTP/1.1
Host: 
Content-Type: application/x-www-form-urlencoded
Content-Length: 27
name=John&age=30

• Visibility: The parameters are not displayed in the URL, and the user cannot see the specific transferred content.
• limit: There is almost no data size limit, and large files can be transferred.
• Idepotency: POST requests are not idempotent, and each request will have a different impact on the server resources (such as adding new data).
• cache: POST requests will not be cached by the browser by default.

advantage：

• The security is slightly higher than that of GET (the parameters are not directly exposed to the URL, but the data is still protected with HTTPS).
• Supports the transmission of large amounts of data, suitable for complex data submissions.

shortcoming：

• It is not as intuitive as GET, and cannot be shared directly through URLs.
• Compared to GET, the performance may be slightly lower (requires more resources to handle the request body).

3. Summary and comparison

Select method：

• GET: Suitable for scenarios where data is only obtained and no side effects, such as loading web page content.
• POST: Suitable for submitting form data, uploading files or other scenarios where server data needs to be modified.

2. PUT and DELETE

PUTandDELETEThese are two methods in the HTTP protocol, mainly used to perform modification and deletion operations on resources. They andGET、POSTLikewise, they are basic methods defined in HTTP/1.1 and are often used in RESTful API.

1. PUT method

Features

• Purpose: Used to create or update resources.

  • If the specified resourceDoes not exist, create a new resource.
  • If the specified resourceAlready exists, the resource is updated.

• Idepotency: PUT is idempotent, and repeatedly sending the same PUT requests will not have additional impact on the server's status (the same data will overwrite existing resources).

• Request body: The PUT request body contains data that needs to be created or updated.

Example

Scene: Create or update user information.

ask:

PUT /users/123 HTTP/1.1
Host: 
Content-Type: application/json
Content-Length: 47
{
  "username": "johndoe",
  "email": "john@"
}

• Target resources:/users/123(Resource with user ID 123).
• Request body: Contains user data.

response:

• Successfully created the resource:201 Created
• Resources updated successfully:200 OK

2. DELETE method

Features

• use: Used to delete the specified resource on the server.
• Idepotency:DELETE is also idempotent. Send multiple DELETE requests to the same resource, and the result is the same: the resource is deleted (or no longer exists).
• Request body: Usually no request body is needed, resource information is specified by the URL.

Example

Scene: Delete user information.

ask：

DELETE /users/123 HTTP/1.1
Host: 

• Target resources:/users/123(Resource with user ID 123).

response：

• Deletion successfully:200 OKor204 No Content
• The resource does not exist:404 Not Found

3. The difference between PUT and DELETE

4. Comparison between PUT and POST

• PUTis idempotent, usually specifying the full path to the resource (e.g./users/123),emphasizeResource replacement。
• POSTNot idempotent, usually operates on resource collections (such as/users),emphasizeNew resources。

5. RESTful API Practical Recommendations

• PUT: Used toAlready have resourcesMake modifications, or create a resource with the resource path known.
• DELETE: Used to delete specified resources and ensure resource uniqueness.
• POST: Used to add new resources, especially when the path is unknown or the creation rules are complex.

3. Summary

1. GET (read data)

• effect：Get data from the server
• Parameter position: Pass parameters through the query string of the URL.
• Request body: No request body.
• Idepotency: Idempotropic, the result of multiple requests is the same.
• Applicable scenarios: Load web page content, obtain user information, etc.
• Example:

GET /users/123 HTTP/1.1

2. POST (create data)

• effect：Submit data to the server, usually used to create new resources

• Parameter position: Data is passed in the request body.

• Request body: There is a request body (such as form data or JSON).

• Idepotency: Non-idempotent, new resources may be created per request.

• Applicable scenarios: Submit forms, add new users, upload files, etc.

• Example:

POST /users HTTP/1.1
Content-Type: application/json
{
  "username": "johndoe",
  "email": "john@"
}

3. PUT (create or update data)

• effect：Create or update a specified resource

• Parameter position: Data is passed in the request body.

• Request body: There is a request body (including complete resource data).

• Idepotency: Idempotropic, the results of multiple requests are consistent.

• Applicable scenarios: Update user information, replace files, etc.

• Example:

PUT /users/123 HTTP/1.1
Content-Type: application/json
{
  "username": "newname",
  "email": "new@"
}

4. DELETE (delete data)

• effect：Delete specified resource from the server

• Parameter position: The resource is specified via the URL.

• Request body: Usually no request body.

• Idepotency: Idempogenic, multiple requests have the same result (resources are deleted).

• Applicable scenarios: Delete users, delete files, etc.

• Example:

DELETE /users/123 HTTP/1.1

Summary comparison table

Simply put:

• GET= Check.
• POST= Increase.
• PUT= Change (or overwrite).
• DELETE= Delete.

4. HTTP status code collection

This form has been verified and complies with the latest HTTP standards.

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