如何在 Python 中为 AJAX 实现一个最小的服务器? [英] How to implement a minimal server for AJAX in Python?
问题描述
我想为 Python 程序创建一个非常简单的基于 HTML/AJAX 的 GUI.所以前端是一个 HTML 页面，它通过 AJAX 与程序通信.你能给我一个使用 python SimpleHTTPServer.SimpleHTTPRequestHandler 的服务器端的最小实现吗?
I want to create a very simple HTML/AJAX based GUI for a Python program. So the frontend is a HTML page which communicates with the program via AJAX. Can you give me a minimal implementation for the server-side using the python SimpleHTTPServer.SimpleHTTPRequestHandler?
一个简单的例子是一个文本框和一个按钮.当按钮被按下时，该字段的内容被发送到服务器，然后服务器发回相应的答案.我知道在 Python 中有许多强大的解决方案，但我想保持这个非常简单.我已经为这样的服务器找到了一些很好的例子(例如 here)，但是所以到目前为止，我无法想出一个真正最小的.
A simple example would be a textfield and a button. When the button is pressed the content of the field is send to the server which then sends back a corresponding answer. I am aware that there are many powerful solutions for this in Python, but I would like to keep this very simple. I already found some nice examples for such a server (e.g. here), but so far I could not come up with a truly minimal one.
如果你想知道我为什么要以这种方式实现 GUI:我对这个应用程序的关注是在一个漂亮的布局中显示大量数据，只需要最少的交互 - 所以使用 HTML+CSS 似乎最方便(而且我已经将其用于非交互式数据显示).
In case you wonder why I want to implement the GUI in such a way: My focus for this application is to display lots of data in a nice layout with only minimal interaction - so using HTML+CSS seems most convenient (and I have been already using it for non-interactive data display).
推荐答案
好的，我想我现在可以回答我自己的问题了.这是用于计算服务器上数字的平方的示例实现.如果有任何改进或误解，请告诉我.
O.K., I think I can now answer my own question. Here is an example implementation for calculating the square of a number on the server. Please let me know if there are any improvements or misconceptions.
python 服务器文件:
the python server file:
import threading
import webbrowser
import BaseHTTPServer
import SimpleHTTPServer
FILE = 'frontend.html'
PORT = 8080
class TestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
"""The test example handler."""
def do_POST(self):
"""Handle a post request by returning the square of the number."""
length = int(self.headers.getheader('content-length'))
data_string = self.rfile.read(length)
try:
result = int(data_string) ** 2
except:
result = 'error'
self.wfile.write(result)
def open_browser():
"""Start a browser after waiting for half a second."""
def _open_browser():
webbrowser.open('http://localhost:%s/%s' % (PORT, FILE))
thread = threading.Timer(0.5, _open_browser)
thread.start()
def start_server():
"""Start the server."""
server_address = ("", PORT)
server = BaseHTTPServer.HTTPServer(server_address, TestHandler)
server.serve_forever()
if __name__ == "__main__":
open_browser()
start_server()
...以及 HTML 文件(我称之为frontend.html"，不幸的是，该名称也必须出现在 JavaScript 代码中):
...and the HTML file (I call it 'frontend.html', unfortunately the name has to appear in the JavaScript code as well):
<html>
<head>
<title>AJAX test</title>
</head>
<body>
<script type="text/javascript">
function xml_http_post(url, data, callback) {
var req = false;
try {
// Firefox, Opera 8.0+, Safari
req = new XMLHttpRequest();
}
catch (e) {
// Internet Explorer
try {
req = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) {
try {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {
alert("Your browser does not support AJAX!");
return false;
}
}
}
req.open("POST", url, true);
req.onreadystatechange = function() {
if (req.readyState == 4) {
callback(req);
}
}
req.send(data);
}
function test_button() {
var data = document.test_form.test_text.value;
xml_http_post("frontend.html", data, test_handle)
}
function test_handle(req) {
var elem = document.getElementById('test_result')
elem.innerHTML = req.responseText
}
</script>
<form name=test_form>
sqr(
<input type="text" name="test_text" value="0" size="4">
) =
<span id="test_result">0</span>
<input type=button onClick="test_button();" value="start" title="start">
</form>
</body>
</html>
当然对于 XML 请求使用 jQuery 会方便得多，但是为简单起见，我将保持原样.
Of course it would be much more convenient to use jQuery for the XML request, but in the interest of simplicity I'll leave it like that.
最后一个使用 WSGI 的替代实现(不幸的是，如果请求不是 POST，我没有看到一种方法可以回退到标准文件服务处理程序):
Finally an alternative implementation using WSGI (unfortunately I didn't see a way to fall back on the standard file-serving handler if the request is not a POST):
import threading
import webbrowser
from wsgiref.simple_server import make_server
FILE = 'frontend.html'
PORT = 8080
def test_app(environ, start_response):
if environ['REQUEST_METHOD'] == 'POST':
try:
request_body_size = int(environ['CONTENT_LENGTH'])
request_body = environ['wsgi.input'].read(request_body_size)
except (TypeError, ValueError):
request_body = "0"
try:
response_body = str(int(request_body) ** 2)
except:
response_body = "error"
status = '200 OK'
headers = [('Content-type', 'text/plain')]
start_response(status, headers)
return [response_body]
else:
response_body = open(FILE).read()
status = '200 OK'
headers = [('Content-type', 'text/html'),
('Content-Length', str(len(response_body)))]
start_response(status, headers)
return [response_body]
def open_browser():
"""Start a browser after waiting for half a second."""
def _open_browser():
webbrowser.open('http://localhost:%s/%s' % (PORT, FILE))
thread = threading.Timer(0.5, _open_browser)
thread.start()
def start_server():
"""Start the server."""
httpd = make_server("", PORT, test_app)
httpd.serve_forever()
if __name__ == "__main__":
open_browser()
start_server()
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