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Python的PIL库实现验证码图片 #67

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myyyy opened this issue Mar 16, 2018 · 0 comments
Open

Python的PIL库实现验证码图片 #67

myyyy opened this issue Mar 16, 2018 · 0 comments
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@myyyy
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@myyyy myyyy commented Mar 16, 2018

现在的网页中,为了防止机器人提交表单,图片验证码是很常见的应对手段之一。这里就不详细介绍了,相信大家都遇到过。

现在就给出用Python的PIL库实现验证码图片的代码。代码中有详细注释。

#!/usr/bin/env python
    #coding=utf-8
    import random
    from PIL import Image, ImageDraw, ImageFont, ImageFilter

    _letter_cases = "abcdefghjkmnpqrstuvwxy" # 小写字母,去除可能干扰的i,l,o,z
    _upper_cases = _letter_cases.upper() # 大写字母
    _numbers = ''.join(map(str, range(3, 10))) # 数字
    init_chars = ''.join((_letter_cases, _upper_cases, _numbers))

    def create_validate_code(size=(120, 30),
                             chars=init_chars,
                             img_type="GIF",
                             mode="RGB",
                             bg_color=(255, 255, 255),
                             fg_color=(0, 0, 255),
                             font_size=18,
                             font_type="ae_AlArabiya.ttf",
                             length=4,
                             draw_lines=True,
                             n_line=(1, 2),
                             draw_points=True,
                             point_chance = 2):
        '''
        @todo: 生成验证码图片
        @param size: 图片的大小,格式(宽,高),默认为(120, 30)
        @param chars: 允许的字符集合,格式字符串
        @param img_type: 图片保存的格式,默认为GIF,可选的为GIF,JPEG,TIFF,PNG
        @param mode: 图片模式,默认为RGB
        @param bg_color: 背景颜色,默认为白色
        @param fg_color: 前景色,验证码字符颜色,默认为蓝色#0000FF
        @param font_size: 验证码字体大小
        @param font_type: 验证码字体,默认为 ae_AlArabiya.ttf
        @param length: 验证码字符个数
        @param draw_lines: 是否划干扰线
        @param n_lines: 干扰线的条数范围,格式元组,默认为(1, 2),只有draw_lines为True时有效
        @param draw_points: 是否画干扰点
        @param point_chance: 干扰点出现的概率,大小范围[0, 100]
        @return: [0]: PIL Image实例
        @return: [1]: 验证码图片中的字符串
        '''

        width, height = size # 宽, 高
        img = Image.new(mode, size, bg_color) # 创建图形
        draw = ImageDraw.Draw(img) # 创建画笔

        def get_chars():
            '''生成给定长度的字符串,返回列表格式'''
            return random.sample(chars, length)

        def create_lines():
            '''绘制干扰线'''
            line_num = random.randint(*n_line) # 干扰线条数

            for i in range(line_num):
                # 起始点
                begin = (random.randint(0, size[0]), random.randint(0, size[1]))
                #结束点
                end = (random.randint(0, size[0]), random.randint(0, size[1]))
                draw.line([begin, end], fill=(0, 0, 0))

        def create_points():
            '''绘制干扰点'''
            chance = min(100, max(0, int(point_chance))) # 大小限制在[0, 100]
           
            for w in xrange(width):
                for h in xrange(height):
                    tmp = random.randint(0, 100)
                    if tmp > 100 - chance:
                        draw.point((w, h), fill=(0, 0, 0))

        def create_strs():
            '''绘制验证码字符'''
            c_chars = get_chars()
            strs = ' %s ' % ' '.join(c_chars) # 每个字符前后以空格隔开
           
            font = ImageFont.truetype(font_type, font_size)
            font_width, font_height = font.getsize(strs)

            draw.text(((width - font_width) / 3, (height - font_height) / 3),
                        strs, font=font, fill=fg_color)
           
            return ''.join(c_chars)

        if draw_lines:
            create_lines()
        if draw_points:
            create_points()
        strs = create_strs()

        # 图形扭曲参数
        params = [1 - float(random.randint(1, 2)) / 100,
                  0,
                  0,
                  0,
                  1 - float(random.randint(1, 10)) / 100,
                  float(random.randint(1, 2)) / 500,
                  0.001,
                  float(random.randint(1, 2)) / 500
                  ]
        img = img.transform(size, Image.PERSPECTIVE, params) # 创建扭曲

        img = img.filter(ImageFilter.EDGE_ENHANCE_MORE) # 滤镜,边界加强(阈值更大)

        return img, strs

    if __name__ == "__main__":
        code_img = create_validate_code()

        code_img[0].save("validate.gif", "GIF")

最后结果返回一个元组,第一个返回值是Image类的实例,第二个参数是图片中的字符串(比较是否正确的作用)。

最后结果返回一个元组,第一个返回值是Image类的实例,第二个参数是图片中的字符串(比较是否正确的作用)。

需要提醒的是,如果在生成ImageFont.truetype实例的时候抛出IOError异常,有可能是运行代码的电脑没有包含指定的字体,需要下载安装。

生成的验证码图片效果:

这时候,细心的同学可能要问,如果每次生成验证码,都要先保存生成的图片,再显示到页面。这么做让人太不能接受了。这个时候,我们需要使用python内置的StringIO模块,它有着类似file对象的行为,但是它操作的是内存文件。于是,我们可以这么写代码:

try:
    import cStringIO as StringIO
except ImportError:
    import StringIO

mstream = StringIO.StringIO()
    
img = create_validate_code()[0]
img.save(mstream, "GIF")

这样,我们需要输出的图片的时候只要使用“mstream.getvalue()”即可。比如在Django里,我们首先定义这样的url:

from django.conf.urls.defaults import *

urlpatterns = patterns('example.views',
    url(r'^validate/$', 'validate', name='validate'),
)

在views中,我们把正确的字符串保存在session中,这样当用户提交表单的时候,就可以和session中的正确字符串进行比较。

from django.shortcuts import HttpResponse

from validate import create_validate_code

def validate(request):
    mstream = StringIO.StringIO()
    
    validate_code = create_validate_code()
    img = validate_code[0]
    img.save(mstream, "GIF")
    
    request.session['validate'] = validate_code[1]
    
    return HttpResponse(mstream.getvalue(), "image/gif")

如果是使用python的bottle框架,可以这么写:

from lib.bottle import Bottle,response
import sys,hashlib,traceback,StringIO

@app.route('/')
@app.route('/code')
def get_code():
  try: 
    stringio = StringIO.StringIO()
    code_img = verifycode.create_validate_code()
    img = code_img[0]
    img.save(stringio, "GIF") 
    print code_img[1]
    response.headers['Content-Type'] = 'image/jpeg'
    return stringio.getvalue()
    #response.body=stringio.getvalue()
    #return response
  except:
    traceback.print_exc()

原文地址:http://blog.csdn.net/csapr1987/article/details/7728315

@myyyy myyyy added the python label Mar 16, 2018
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