〇、知识点
jquery ajax 文档 告诉你可以使用默认的 application/x-www-form-urlencoded, multipart/form-data, or text/plain
这三种,其它的也可以,但是需要告诉ajax 的怎样序列化它。——这句话来源于:https://www.cnblogs.com/htoooth/p/7242217.html
一、原生ajax、不使用表单(Form)
app.py
import os from flask import Flask, request, jsonify, render_template from werkzeug import secure_filename UPLOAD_FOLDER = 'uploads' ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif']) app = Flask(__name__) app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER def allowed_file(filename): return '.' in filename and \ filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS @app.route('/') def index(): return render_template('index.html') @app.route('/uploadfile', methods=['POST']) def upload_file(): if request.method == 'POST': print('request.files', dir(request.files)) file = request.files['file'] if file and allowed_file(file.filename): filename = secure_filename(file.filename) url = os.path.join(app.config['UPLOAD_FOLDER'], filename) file.save(url) return jsonify(dict(url=url,)), 201 if __name__ == "__main__": app.run(debug=True)
index.html
DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Flask上传图片演示三title>
head>
<body>
<h1>Flask上传本地图片示例三h1>
<p>不使用表单Form,原生javascript实现ajax,返回上传的图片所保存的位置p>
<input type="file" name="file" />
<br>
<input type="button" value="上传" />
<p id="res">p>
<script>
var file = document.querySelector('input[type="file"]');
var btn = document.querySelector('input[type="button"]');
//ajax
btn.addEventListener('click', function(event){
event.preventDefault();
var data = new FormData();
data.append(file.name, file.files[0]);var xhr = new XMLHttpRequest();
xhr.open('POST', '/uploadfile', true);
//xhr.setRequestHeader("Content-Type", "multipart\/form-data;"); //千万不能要这一句,否则后台request.files读不到file
xhr.send(data);
xhr.addEventListener('loadend', function(){
if(xhr.status == 201){
var res_json = JSON.parse(xhr.responseText);
document.querySelector('#res').innerHTML = "上传的图片保存在:" + res_json.url;
}
}, false);
}, false);
script>
body>
html>
二、原生ajax、使用表单(Form)
app.py
import os from flask import Flask, request, jsonify, render_template from werkzeug import secure_filename UPLOAD_FOLDER = 'uploads' ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif']) app = Flask(__name__) app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER def allowed_file(filename): return '.' in filename and \ filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS @app.route('/') def index(): return render_template('index.html') @app.route('/uploadfile', methods=['POST']) def upload_file(): if request.method == 'POST': file = request.files['file'] if file and allowed_file(file.filename): filename = secure_filename(file.filename) url = os.path.join(app.config['UPLOAD_FOLDER'], filename) file.save(url) return jsonify(dict(url=url,)), 201 if __name__ == "__main__": app.run(debug=True)
index.html
DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Flask上传图片演示二title>
head>
<body>
<h1>Flask上传本地图片示例二h1>
<p>使用表单Form,原生javascript实现ajax,返回上传的图片所保存的位置p>
<form>
<input type="file" name="file"/>
<br>
<input type="submit" value="上传"/>
form>
<p id="res">p>
<script>
var form = document.querySelector('form');
//ajax
form.addEventListener('submit', function(event){
event.preventDefault();
var xhr = new XMLHttpRequest();
xhr.open('POST', '/uploadfile', true);
xhr.send(new FormData(form)); //注意:不需要设置Content-Type
xhr.addEventListener('loadend', function() {
if(xhr.status == 201){
var res_json = JSON.parse(xhr.responseText);
document.querySelector('#res').innerHTML = "上传的图片保存在:" + res_json.url;
}
}, false);
}, false);
script>
body>
html>
三、无ajax、只使用表单(Form)
app.py
import os from flask import Flask, request, redirect, url_for, render_template from werkzeug import secure_filename UPLOAD_FOLDER = 'uploads' ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif']) app = Flask(__name__) app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER def allowed_file(filename): return '.' in filename and \ filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS @app.route('/') def index(): return render_template('index.html') @app.route('/uploadfile', methods=['POST']) def upload_file(): if request.method == 'POST': file = request.files['file'] if file and allowed_file(file.filename): filename = secure_filename(file.filename) file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename)) return redirect(url_for('uploaded_file', filename=filename)) from flask import send_from_directory @app.route('/uploads/') def uploaded_file(filename): return send_from_directory(app.config['UPLOAD_FOLDER'], filename) if __name__ == "__main__": app.run(debug=True)
index.html
DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Flask上传图片演示一title>
head>
<body>
<h1>Flask上传本地图片示例一h1>
<p>使用表单Form,无javascript,跳转显示上传的图片p>
<form action="/uploadfile" enctype='multipart/form-data' method='POST'>
<input type="file" name="file" style="margin-top:20px;"/>
<br>
<input type="submit" value="上传" style="margin-top:15px;"/>
form>
body>
html>
四、预览、无Form、原生ajax
index.html
DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Flask上传图片演示四title>
head>
<body>
<h1>Flask上传本地图片示例四h1>
<p>上传前预览图片,不使用表单Form,原生ajax,返回上传的图片所保存的位置p>
<img id="base64image" src="" style="max-height:150px;"/>
<br />
<input type="file" name="image" accept="image/gif,image/jpeg,image/jpg,image/png,image/svg"/>
<br />
<input type="button" value="上传"/>
<p id="res">p>
<script>
var base64image = document.querySelector('#base64image');
var fileElement = document.querySelector('input[type="file"]');
var btnElement = document.querySelector('input[type="button"]');
//预览
fileElement.addEventListener('change', function(event){
if (!event.target.files || !event.target.files[0]) {
return;
}
var reader = new FileReader();
reader.readAsDataURL(event.target.files[0]);
reader.addEventListener("load", function(e){
base64image.src = e.target.result; //base64编码
}, false);
},false);
//ajax
btnElement.addEventListener('click', function(event){
event.preventDefault();
var data = new FormData();
data.append(fileElement.name, fileElement.files[0]); //添加图片信息
var xhr = new XMLHttpRequest();
xhr.open("post", "/uploadfile", true);//true即异步
//xhr.setRequestHeader('Content-Type', 'multipart/form-data'); //千万别写这句!!
xhr.send(data);
xhr.addEventListener("loadend", function(event){
if(xhr.status == 201){ // 201,去看app.py!!
var res = JSON.parse(xhr.responseText); //接收的是json数据
console.log(res);
}
}, false);
},false);
script>
body>
html>