輪詢與長輪詢

本文轉載自查看原文 2018-07-03 15:18 870 爬蟲

輪詢

通過定時器每隔多少秒發送一次請求。

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <style>
        li{
            cursor: pointer;
        }
    </style>
</head>
<body>
    <ul id="userList">
        {% for key,val in users.items() %}
            <li uid="{{key}}">{{val.name}} ({{val.count}})</li>
        {% endfor %}
    </ul>

    <script src="https://cdn.bootcss.com/jquery/3.3.0/jquery.min.js"></script>
    <script>

        $(function () {
            $('#userList').on('dblclick','li',function () {
                var uid = $(this).attr('uid');
                $.ajax({
                    url:'/vote',
                    type:'POST',
                    data:{uid:uid},
                    success:function (arg) {
                        console.log(arg);
                    }
                })
            });

        });
        /*
        獲取投票信息
         */
        function get_vote() {
            $.ajax({
                url:'/get/vote',
                type:"GET",
                dataType:'JSON',
                success:function (arg) {
                    $('#userList').empty();
                    $.each(arg,function (k,v) {
                        var li = document.createElement('li');
                        li.setAttribute('uid',k);
                        li.innerText = v.name + "(" + v.count + ')' ;
                        $('#userList').append(li);
                    })

                }
            })
        }
        
        setInterval(get_vote,3000);
    </script>
</body>
</html>

user_list.html

app.py

from flask import Flask,render_template,request,jsonify


app = Flask(__name__)


USERS = {
    '1':{'name':'貝貝','count':1},
    '2':{'name':'小東北','count':0},
    '3':{'name':'何偉明','count':0},
}

@app.route('/user/list')
def user_list():
    import time
    return render_template('user_list.html',users=USERS)

@app.route('/vote',methods=['POST'])
def vote():
    uid = request.form.get('uid')
    USERS[uid]['count'] += 1
    return "投票成功"

@app.route('/get/vote',methods=['GET'])
def get_vote():

    return jsonify(USERS)


if __name__ == '__main__':
    # app.run(host='192.168.13.253',threaded=True)
    app.run(threaded=True) #多線程

app1.py　

from flask import Flask,render_template,request,jsonify

app = Flask(__name__)

import queue

q = queue.Queue()

@app.route('/get/vote')
def get_vote():
    try:
        val = q.get(timeout=20)
    except queue.Empty:
        val = "已超時"

    return val

@app.route('/vote')
def vote():
    q.put('10')
    return '投票成功'

if __name__ == '__main__':
    # app.run(host='192.168.13.253',threaded=True)
    app.run(threaded=True)

隊列.py

import queue

q = queue.Queue()

q.put('123')

val = q.get()
print(val)

try:
    val = q.get(timeout=5)
    print(val)
except queue.Empty:
    pass

長輪詢　

用法：讓瀏覽器發送一次請求，會把請求夯住，最多會夯住多少秒，如果在這一段時間內，沒有人再來發送數據，就讓他等30秒釋放，如果在這30秒中有人發數據，會立即拿到結果立即返回。

優勢：結果實時化，省去了連接的次數　

應用場景：

　　-實時

　　-在線

websocket也可以實現以上場景，但兼容性不好（基於html5）

長輪詢兼容性好

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <style>
        li{
            cursor: pointer;
        }
    </style>
</head>
<body>
    <ul id="userList">
        {% for key,val in users.items() %}
            <li uid="{{key}}">{{val.name}} ({{val.count}})</li>
        {% endfor %}
    </ul>

    <script src="https://cdn.bootcss.com/jquery/3.3.0/jquery.min.js"></script>
    <script>

        $(function () {
            $('#userList').on('click','li',function () {
                var uid = $(this).attr('uid');
                $.ajax({
                    url:'/vote',
                    type:'POST',
                    data:{uid:uid},
                    success:function (arg) {
                        console.log(arg);
                    }
                })
            });
            get_vote();
        });

        /*
        獲取投票信息
         */
        function get_vote() {
            $.ajax({
                url:'/get/vote',
                type:"GET",
                dataType:'JSON',
                success:function (arg) {
                    if(arg.status){
                        $('#userList').empty();
                            $.each(arg.data,function (k,v) {
                                var li = document.createElement('li');
                                li.setAttribute('uid',k);
                                li.innerText = v.name + "(" + v.count + ')' ;
                                $('#userList').append(li);
                            })
                    }
                    get_vote();

                }
            })
        }
    </script>
</body>
</html>

user_list.html

app.py

from flask import Flask,render_template,request,jsonify,session
import uuid
import queue

app = Flask(__name__)
app.secret_key = 'asdfasdfasd'


USERS = {
    '1':{'name':'貝貝','count':1},
    '2':{'name':'小東北','count':0},
    '3':{'name':'何偉明','count':0},
}

QUEQUE_DICT = {
    # 'asdfasdfasdfasdf':Queue()
}

@app.route('/user/list')
def user_list():
    user_uuid = str(uuid.uuid4())
    QUEQUE_DICT[user_uuid] = queue.Queue()

    session['current_user_uuid'] = user_uuid
    return render_template('user_list.html',users=USERS)

@app.route('/vote',methods=['POST'])
def vote():
    uid = request.form.get('uid')
    USERS[uid]['count'] += 1
    for q in QUEQUE_DICT.values():
        q.put(USERS)
    return "投票成功"


@app.route('/get/vote',methods=['GET'])
def get_vote():
    user_uuid = session['current_user_uuid']
    q = QUEQUE_DICT[user_uuid]

    ret = {'status':True,'data':None}
    try:
        users = q.get(timeout=5)
        ret['data'] = users
    except queue.Empty:
        ret['status'] = False

    return jsonify(ret)



if __name__ == '__main__':
    app.run(host='192.168.13.253',threaded=True)
    # app.run(threaded=True)

app1.py　

from flask import Flask,render_template,request,jsonify

app = Flask(__name__)

import queue

q = queue.Queue()

@app.route('/get/vote')
def get_vote():
    try:
        val = q.get(timeout=20)
    except queue.Empty:
        val = "已超時"

    return val

@app.route('/vote')
def vote():
    q.put('10')
    return '投票成功'

if __name__ == '__main__':
    # app.run(host='192.168.13.253',threaded=True)
    app.run(threaded=True)

隊列.py　

import queue

q = queue.Queue()

q.put('123')

val = q.get()
print(val)

try:
    val = q.get(timeout=5)
    print(val)
except queue.Empty:
    pass

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