flask使用原生ajax、不使用表单(Form)上传文件 -云博客

flask使用原生ajax、不使用表单(Form)上传文件

# 前端 2024-05-05 15:32 0 49 来源：云博客

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 osfrom flask import Flask, request, jsonify, render_templatefrom werkzeug import secure_filenameUPLOAD_FOLDER = ‘uploads‘ALLOWED_EXTENSIONS = set([‘txt‘, ‘pdf‘, ‘png‘, ‘jpg‘, ‘jpeg‘, ‘gif‘])app = Flask(__name__)app.config[‘UPLOAD_FOLDER‘] = UPLOAD_FOLDERdef 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,)), 201if __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 osfrom flask import Flask, request, jsonify, render_templatefrom werkzeug import secure_filenameUPLOAD_FOLDER = ‘uploads‘ALLOWED_EXTENSIONS = set([‘txt‘, ‘pdf‘, ‘png‘, ‘jpg‘, ‘jpeg‘, ‘gif‘])app = Flask(__name__)app.config[‘UPLOAD_FOLDER‘] = UPLOAD_FOLDERdef 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,)), 201if __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 enctype=‘multipart/form-data‘> 注意：非必须指定enctype=‘multipart/form-data‘ --> <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 osfrom flask import Flask, request, redirect, url_for, render_templatefrom werkzeug import secure_filenameUPLOAD_FOLDER = ‘uploads‘ALLOWED_EXTENSIONS = set([‘txt‘, ‘pdf‘, ‘png‘, ‘jpg‘, ‘jpeg‘, ‘gif‘])app = Flask(__name__)app.config[‘UPLOAD_FOLDER‘] = UPLOAD_FOLDERdef 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/<filename>‘)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‘> <!-- 注意：三个全指定action, enctype, method --> <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>