Python的StringIO模块和cStringIO模块

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1.StringIO模块

StringIO用于像文件一样对字符串缓冲区或者叫做内存文件进行读写。
    f = StringIO()      # ready for writing
    f = StringIO(buf)   # ready for reading
    f.close()           # explicitly release resources held
    flag = f.isatty()   # always false
    pos = f.tell()      # get current position
    f.seek(pos)         # set current position
    f.seek(pos, mode)   # mode 0: absolute; 1: relative; 2: relative to EOF
    buf = f.read()      # read until EOF
    buf = f.read(n)     # read up to n bytes
    buf = f.readline()  # read until end of line ('\n') or EOF
    list = f.readlines()# list of f.readline() results until EOF
    f.truncate([size])  # truncate file at to at most size (default: current pos)
    f.write(buf)        # write at current position
    f.writelines(list)  # for line in list: f.write(line)
    f.getvalue()        # return whole file's contents as a string

在有些时候python调用shell命令或者使用socket向端口发送命令后返回一大串分行的字符串。就可以使用StringIO对这些字符串分行读写。
例如向ZooKeeper的端口发送mntr命令

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import socket s=socket.socket() s.connect(('localhost',2181)) s.send('mntr') data_mntr=s.recv(2048) s.close() print data_mntr

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# python test.py zk_version3.4.6-1569965, built on 02/20/2014 09:09 GMT zk_avg_latency0 zk_max_latency0 zk_min_latency0 zk_packets_received335 zk_packets_sent334 zk_num_alive_connections1 zk_outstanding_requests0 zk_server_statefollower zk_znode_count17159 zk_watch_count0 zk_ephemerals_count1 zk_approximate_data_size6666471 zk_open_file_descriptor_count27 zk_max_file_descriptor_count102400

data_mntr返回的数据就是一个string buffer，如果需要对每行数据进行读写，就需要像文件那样使用readline()或者readlines()

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#!/usr/bin/python import socket from StringIO import StringIO s=socket.socket() s.connect(('localhost',2181)) s.send('mntr') data_mntr=s.recv(2048) s.close() h=StringIO(data_mntr) print h.readline() print h.readlines()

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# python test.py zk_version3.4.6-1569965, built on 02/20/2014 09:09 GMT ['zk_avg_latency\t0\n', 'zk_max_latency\t0\n', 'zk_min_latency\t0\n', 'zk_packets_received\t347\n', 'zk_packets_sent\t346\n', 'zk_num_alive_connections\t1\n', 'zk_outstanding_requests\t0\n', 'zk_server_state\tfollower\n', 'zk_znode_count\t17159\n', 'zk_watch_count\t0\n', 'zk_ephemerals_count\t1\n', 'zk_approximate_data_size\t6666471\n', 'zk_open_file_descriptor_count\t27\n', 'zk_max_file_descriptor_count\t102400\n']

2.cStringIO模块
cStringIO模块和StringIO模块功能类似。不过这个模块是用C语言编写的。

将以上的

1	from StringIO import StringIO

直接换成

1	from cStringIO import StringIO