python实战–Http代理服务器-爱站

最近打算好好深入研究下python的socket编程，于是打算学习下，仿写了一下，发现写好还真不容易，中途出现很多问题，果真是看的容易，做起来难啊

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import socket
import thread
import urlparse
import select
  
BUFLEN=8192
  
  
class Proxy(object):
    def __init__(self,conn,addr):
        self.source=conn
        self.request=""
        self.headers={}
        self.destnation=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.run()
  
    def get_headers(self):
        header=''
        while True:
            header+=self.source.recv(BUFLEN)
            index=header.find('\n')
            if index >0:
                break
        #firstLine,self.request=header.split('\r\n',1) 
        firstLine=header[:index]
        self.request=header[index+1:]
        self.headers['method'],self.headers['path'],self.headers['protocol']=firstLine.split()
  
    def conn_destnation(self):
        url=urlparse.urlparse(self.headers['path'])
        hostname=url[1]
        port="80"
        if hostname.find(':') >0:
            addr,port=hostname.split(':')
        else:
            addr=hostname
        port=int(port)
        ip=socket.gethostbyname(addr)
        print ip,port
        self.destnation.connect((ip,port))
        data="%s %s %s\r\n" %(self.headers['method'],self.headers['path'],self.headers['protocol'])
        self.destnation.send(data+self.request)
        print data+self.request
  
  
    def renderto(self):
        readsocket=[self.destnation]
        while True:
            data=''
            (rlist,wlist,elist)=select.select(readsocket,[],[],3)
            if rlist:
                data=rlist[0].recv(BUFLEN)
                if len(data)>0:
                    self.source.send(data)
                else:
                    break
    def run(self):
        self.get_headers()
        self.conn_destnation()
        self.renderto()
  
  
  
class Server(object):
  
    def __init__(self,host,port,handler=Proxy):
        self.host=host
        self.port=port
        self.server=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,1)
        self.server.bind((host,port))
        self.server.listen(5)
        self.handler=handler
  
    def start(self):
        while True:
            try:
                conn,addr=self.server.accept()
                thread.start_new_thread(self.handler,(conn,addr))
            except:
                pass
  
  
if __name__=='__main__':
    s=Server('127.0.0.1',8080)
    s.start()
import socket
import thread
import urlparse
import select
BUFLEN=8192
class Proxy(object):
    def __init__(self,conn,addr):
        self.source=conn
        self.request=""
        self.headers={}
        self.destnation=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.run()
    def get_headers(self):
        header=''
        while True:
            header+=self.source.recv(BUFLEN)
            index=header.find('\n')
            if index >0:
                break
        #firstLine,self.request=header.split('\r\n',1)
        firstLine=header[:index]
        self.request=header[index+1:]
        self.headers['method'],self.headers['path'],self.headers['protocol']=firstLine.split()
    def conn_destnation(self):
        url=urlparse.urlparse(self.headers['path'])
        hostname=url[1]
        port="80"
        if hostname.find(':') >0:
            addr,port=hostname.split(':')
        else:
            addr=hostname
        port=int(port)
        ip=socket.gethostbyname(addr)
        print ip,port
        self.destnation.connect((ip,port))
        data="%s %s %s\r\n" %(self.headers['method'],self.headers['path'],self.headers['protocol'])
        self.destnation.send(data+self.request)
        print data+self.request
    def renderto(self):
        readsocket=[self.destnation]
        while True:
            data=''
            (rlist,wlist,elist)=select.select(readsocket,[],[],3)
            if rlist:
                data=rlist[0].recv(BUFLEN)
                if len(data)>0:
                    self.source.send(data)
                else:
                    break
    def run(self):
        self.get_headers()
        self.conn_destnation()
        self.renderto()
  
class Server(object):
    def __init__(self,host,port,handler=Proxy):
        self.host=host
        self.port=port
        self.server=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,1)
        self.server.bind((host,port))
        self.server.listen(5)
        self.handler=handler
    def start(self):
        while True:
            try:
                conn,addr=self.server.accept()
                thread.start_new_thread(self.handler,(conn,addr))
            except:
                pass
if __name__=='__main__':
    s=Server('127.0.0.1',8080)
    s.start()

其实Http代理服务器本身不难，但写出来还是挺费事的，这里就不细说源代码了，很简单。主要说说，我遇到的问题。

一：我本来只知道，thread.start_new_thread的第一个参数是函数对象，但当我看到上面的博文时，心里一愣，这样也可以，于是我迅速的测试了一下：

import thread
  
class Hello:
    def __init__(self,content):
        print content
  
def cs():
        thread.start_new_thread(Hello, ("Hello World",))
  
if __name__=='__main__':
    cs()
import thread
class Hello:
    def __init__(self,content):
        print content
def cs():
        thread.start_new_thread(Hello, ("Hello World",))
if __name__=='__main__':
    cs()

Unhandled exception in thread started by
Error in sys.excepthook:

Original exception was:

Unhandled exception in thread started by
Error in sys.excepthook:

Original exception was:

一看，我说嘛，第一个参数怎么可以是对象，我呵呵一笑，稍微鄙视了一下作者。于是，我洗洗睡了，第二天，我还是不死心，于是把代码下下来，本地实验了一下，可以的，立马意识到是我2了，于是立马百度。

原来thread模块中，主线程如果比子线程先结束，就会抛出这个异常，所以我们必须让子线程先结束，最简单的方法就是让主线程sleep足够长的时间，至于多长时间，貌似不知道，那到底怎么解决呢？

比较好的解决办法就是，主线程给每个子线程都加一把锁，子线程在结束前将锁释放掉，主线程一直循环检查锁的状态。代码如下：

import thread
  
class Hello:
    def __init__(self,content,lock):
        print content
        """
        do something
        ....
        At the end,release the lock
        """
        lock.release()
  
def cs():
        lock=thread.allocate_lock()
        lock.acquire()
        thread.start_new_thread(Hello, ("Hello World",lock))
        while True:
            if not lock.locked():
                break
        print "lock release"
  
if __name__=='__main__':
    cs()
import thread
class Hello:
    def __init__(self,content,lock):
        print content
        """
        do something
        ....
        At the end,release the lock
        """
        lock.release()
def cs():
        lock=thread.allocate_lock()
        lock.acquire()
        thread.start_new_thread(Hello, ("Hello World",lock))
        while True:
            if not lock.locked():
                break
        print "lock release"
if __name__=='__main__':
    cs()