Flask实现图片的上传、下载及展示示例代码

用Flask处理图片非常容易,这一篇学习一下图片的上传、下载及展示。还是以实例代码演示为主。

首先,实现一个简单的上传(过程中未做任何处理,只是为了演示)

点击选择图片,输入李四:

Flask实现图片的上传、下载及展示示例代码

HTML代码:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
  <body>
    <div>
      <form method="post" action="http://localhost:5000/up_photo" enctype="multipart/form-data">
      <input type="file" size="30" name="photo"/>
      <br>
      <input type="text" class="txt_input" name="name" style="margin-top:15px;"/>
      <input type="submit" value="提交信息" class="button-new" style="margin-top:15px;"/>
      </form>
    </div>
  </body>
</html>

点击提交信息后,通过 http://localhost:5000/up_photo,传递到后台对应的路由处理,查看控制台:

Flask实现图片的上传、下载及展示示例代码

后台接收的路由代码:

basedir = os.path.abspath(os.path.dirname(__file__))
 
@app.route('/up_photo', methods=['post'])
def up_photo():
  img = request.files.get('txt_photo')
  username = request.form.get("name")
  path = basedir+"/static/photo/"
  file_path = path+img.filename
  img.save(file_path)
  print '上传头像成功,上传的用户是:'+username
  return render_template('index.html')

此时,我们查看static/photo时,已经可以看到我们点击上传的图片了。

以上是最简单的一个文件上传示例,我们实际使用中基本不可能这样去写,通常会做一些处理。例如:上传后做图片名称唯一性的处理、限制上传文件的类型、无论上传成功或者失败,都去做一些返回提示等等。

限制上传文件类型,例如,我们希望用户上传的文件为图片类型

ALLOWED_EXTENSIONS = set(['png', 'jpg', 'JPG', 'PNG', 'gif', 'GIF'])
 
def allowed_file(filename):
  return '.' in filename and filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS

上面的代码片段通过截取上传文件的后缀名,判断是否是属于我们期望用户上传的类型。

更改上传图片名称,防止重名

这里我们使用日期加随机数生成图片名,做一个生成字符串的工具类

#-*-coding:utf-8-*-
import datetime
import random
class Pic_str:
  def create_uuid(self): #生成唯一的图片的名称字符串,防止图片显示时的重名问题
    nowTime = datetime.datetime.now().strftime("%Y%m%d%H%M%S"); # 生成当前时间
    randomNum = random.randint(0, 100); # 生成的随机整数n,其中0<=n<=100
    if randomNum <= 10:
      randomNum = str(0) + str(randomNum);
    uniqueNum = str(nowTime) + str(randomNum);
    return uniqueNum;

当我们点击图片上传,选择图片点击提交后,页面返回提示信息如下图:

Flask实现图片的上传、下载及展示示例代码

此时看我们工程下的upload文件夹,唯一名称的图片已经上传成功

Flask实现图片的上传、下载及展示示例代码

图片的下载

@app.route('/download/<string:filename>', methods=['GET'])
def download(filename):
  if request.method == "GET":
    if os.path.isfile(os.path.join('upload', filename)):
      return send_from_directory('upload', filename, as_attachment=True)
    pass

图片的展示

# show photo
@app.route('/show/<string:filename>', methods=['GET'])
def show_photo(filename):
  file_dir = os.path.join(basedir, app.config['UPLOAD_FOLDER'])
  if request.method == 'GET':
    if filename is None:
      pass
    else:
      image_data = open(os.path.join(file_dir, '%s' % filename), "rb").read()
      response = make_response(image_data)
      response.headers['Content-Type'] = 'image/png'
      return response
  else:
    pass

完整示例代码

#encoding:utf-8
#!/usr/bin/env python
from werkzeug.utils import secure_filename
from flask import Flask, render_template, jsonify, request, make_response, send_from_directory, abort
import time
import os
from strUtil import Pic_str
import base64
 
app = Flask(__name__)
UPLOAD_FOLDER = 'upload'
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
basedir = os.path.abspath(os.path.dirname(__file__))
ALLOWED_EXTENSIONS = set(['png', 'jpg', 'JPG', 'PNG', 'gif', 'GIF'])
 
def allowed_file(filename):
  return '.' in filename and filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS
 
 
@app.route('/upload')
def upload_test():
  return render_template('up.html')
 
 
# 上传文件
@app.route('/up_photo', methods=['POST'], strict_slashes=False)
def api_upload():
  file_dir = os.path.join(basedir, app.config['UPLOAD_FOLDER'])
  if not os.path.exists(file_dir):
    os.makedirs(file_dir)
  f = request.files['photo']
  if f and allowed_file(f.filename):
    fname = secure_filename(f.filename)
    print fname
    ext = fname.rsplit('.', 1)[1]
    new_filename = Pic_str().create_uuid() + '.' + ext
    f.save(os.path.join(file_dir, new_filename))
 
    return jsonify({"success": 0, "msg": "上传成功"})
  else:
    return jsonify({"error": 1001, "msg": "上传失败"})
 
@app.route('/download/<string:filename>', methods=['GET'])
def download(filename):
  if request.method == "GET":
    if os.path.isfile(os.path.join('upload', filename)):
      return send_from_directory('upload', filename, as_attachment=True)
    pass
  
  
# show photo
@app.route('/show/<string:filename>', methods=['GET'])
def show_photo(filename):
  file_dir = os.path.join(basedir, app.config['UPLOAD_FOLDER'])
  if request.method == 'GET':
    if filename is None:
      pass
    else:
      image_data = open(os.path.join(file_dir, '%s' % filename), "rb").read()
      response = make_response(image_data)
      response.headers['Content-Type'] = 'image/png'
      return response
  else:
    pass
 
 
if __name__ == '__main__':
  app.run(debug=True)

基本示例就以上这些了!

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