搭建简单的CGI应用程序

原文来源于《核心编程3》第10章web编程

一、静态文件+脚本文件

1.首先开启cgiweb服务器

python2 -m CGIHTTPServer 8000

看到如下反应

2.服务器目录新建cgi-bin目录，html文件放入服务器目录，python cgi脚本放入刚刚建好的cgi-bin目录

3.看下html代码和python cgi脚本代码都是些什么内容

friends.htm

 1 <HTML><HEAD><TITLE>
 2 Friends CGI Demo (static screen)
 3 </TITLE></HEAD>
 4 <BODY><H3>Friends list for: <I>NEW USER</I></H3>
 5 <FORM ACTION="/cgi-bin/friendsA.py">
 6 <B>Enter your Name:</B>
 7 <INPUT TYPE=text NAME=person VALUE="NEW USER" SIZE=15>
 8 <P><B>How many friends do you have?</B>
 9 <INPUT TYPE=radio NAME=howmany VALUE="0" CHECKED> 0
10 <INPUT TYPE=radio NAME=howmany VALUE="10"> 10
11 <INPUT TYPE=radio NAME=howmany VALUE="25"> 25
12 <INPUT TYPE=radio NAME=howmany VALUE="50"> 50
13 <INPUT TYPE=radio NAME=howmany VALUE="100"> 100
14 <P><INPUT TYPE=submit></FORM></BODY></HTML>

friends.htm

friendsA.py

 1 #!/usr/bin/env python
 2 
 3 import cgi
 4 
 5 reshtml = '''Content-Type: text/html

 6 <HTML><HEAD><TITLE>
 7 Friends CGI Demo (dynamic screen)
 8 </TITLE></HEAD>
 9 <BODY><H3>Friends list for: <I>%s</I></H3>
10 Your name is: <B>%s</B><P>
11 You have <B>%s</B> friends.
12 </BODY></HTML>'''
13 
14 form = cgi.FieldStorage()
15 who = form['person'].value
16 howmany = form['howmany'].value
17 print reshtml % (who, who, howmany)

friendsA.py

4.运行起来看看，浏览器输入

http://localhost:8000/friends.htm

结果可以看到

我们随意添加一个，点提交

可以看到正文部分变化了，同时地址内容也变化了，

再看下终端，也在有相应的显示。

二、单个脚本文件

　　1.服务器照常开启，脚本文件friendsB.py放在cgi-bin目录下

　　2.代码内容

#coding=utf-8
import cgi

header = 'Content-Type: text/html

'  #需要先返回一个适当的http头文件，再返回结果页面

formhtml = '''<HTML><HEAD><TITLE>
Friends CGI Demo</TITLE></HEAD>
<BODY><H3>Friends list for: <I>NEW USER</I></H3>
<FORM ACTION="/cgi-bin/friendsB.py">
<B>Enter your Name:</B>
<INPUT TYPE=hidden NAME=action VALUE=edit>
<INPUT TYPE=text NAME=person VALUE="NEW USER" SIZE=15>
<P><B>How many friends do you have?</B>
%s
<P><INPUT TYPE=submit></FORM></BODY></HTML>'''

fradio = '<INPUT TYPE=radio NAME=howmany VALUE="%s" %s> %s
'

def showForm():
    friends = []
    for i in (0, 10, 25, 50, 100):
        checked = ''
        if i == 0:
            checked = 'CHECKED'
        friends.append(fradio % (str(i), checked, str(i)))  #灵活输出，避免太多重复

    print '%s%s' % (header, formhtml % ''.join(friends))    #表单页面http头文件和内容都加进去了

reshtml = '''<HTML><HEAD><TITLE>
Friends CGI Demo</TITLE></HEAD>
<BODY><H3>Friends list for: <I>%s</I></H3>
Your name is: <B>%s</B><P>
You have <B>%s</B> friends.
</BODY></HTML>'''

def doResults(who, howmany):
    print header + reshtml % (who, who, howmany)    #结果页面也都加进去了

def process():
    form = cgi.FieldStorage()
    if 'person' in form:
        who = form['person'].value
    else:
        who = 'NEW USER'

    if 'howmany' in form:
        howmany = form['howmany'].value
    else:
        howmany = 0

    if 'action' in form:            #action变量用来判断选择哪个页面，表单页面、结果页面
        doResults(who, howmany)
    else:
        showForm()

if __name__ == '__main__':
    process()

friendsB.py

　　3.浏览器输入

http://localhost:8000/cgi-bin/friendsB.py

会看到一样的界面，提交后也是一样的

三、单个脚本文件，带有用户交互和错误处理

　　1.代码

#coding=utf-8
#!/usr/bin/env python
import cgi
from urllib import quote_plus

header = 'Content-Type: text/html

'
url = '/cgi-bin/friendsC.py'

errhtml = '''<HTML><HEAD><TITLE>
Friends CGI Demo</TITLE></HEAD>
<BODY><H3>ERROR</H3>
<B>%s</B><P>
<FORM><INPUT TYPE=button VALUE=Back
ONCLICK="window.history.back()"></FORM>
</BODY></HTML>'''   #后退按钮

def showError(error_str):   #错误处理部分
    print header + errhtml % error_str

formhtml = '''<HTML><HEAD><TITLE>
Friends CGI Demo</TITLE></HEAD>
<BODY><H3>Friends list for: <I>%s</I></H3>
<FORM ACTION="%s">
<B>Enter your Name:</B>
<INPUT TYPE=hidden NAME=action VALUE=edit>
<INPUT TYPE=text NAME=person VALUE="%s" SIZE=15>
<P><B>How many friends do you have?</B>
%s
<P><INPUT TYPE=submit></FORM></BODY></HTML>'''

fradio = '<INPUT TYPE=radio NAME=howmany VALUE="%s" %s> %s
'

def showForm(who, howmany):
    friends = []
    for i in (0, 10, 25, 50, 100):
        checked = ''
        if str(i) == howmany:   #多传一个参数，用来记录'历史数据'
            checked = 'CHECKED'
        friends.append(fradio % (str(i), checked, str(i)))
    print '%s%s' % (header, formhtml % (
        who, url, who, ''.join(friends)))

reshtml = '''<HTML><HEAD><TITLE>
Friends CGI Demo</TITLE></HEAD>
<BODY><H3>Friends list for: <I>%s</I></H3>
Your name is: <B>%s</B><P>
You have <B>%s</B> friends.
<P>Click <A HREF="%s">here</A> to edit your data again.
</BODY></HTML>'''

def doResults(who, howmany):
    newurl = url + '?action=reedit&person=%s&howmany=%s' % (
        quote_plus(who), howmany)               #表单记录包含

    print header + reshtml % (who, who, howmany, newurl)    #再次编辑回到表单界面

def process():
    error = ''
    form = cgi.FieldStorage()

    if 'person' in form:
        who = form['person'].value.title()
    else:
        who = 'NEW USER'

    if 'howmany' in form:   #根据howmany字段判定有没有选择人数，没有就算有错误，返回错误页面
        howmany = form['howmany'].value
    else:
        if 'action' in form and 
                form['action'].value == 'edit':
            error = 'Please select number of friends.'
        else:
            howmany = 0

    if not error:
        if 'action' in form and 
                form['action'].value != 'reedit':
            doResults(who, howmany)
        else:
            showForm(who, howmany)
    else:
        showError(error)

if __name__ == '__main__':
    process()

friendsC

　　2.用法和B一样，代码结构也差不多，看下使用效果

浏览器输入地址后

提交用户名，但是不提交数量

点back返回，选数量

点击here，里面是个引用

会回到提交表单的地方，保存了"历史记录"

至此一个简单的cgi应用程序完成了。