程序语言中的正则表达式

java处理正则表达式

读取文件，并解析文件中的ip地址。例子：

package getIP;
import java.io.BufferedReader; import java.io.File; import java.io.FileReader; import java.io.IOException; import java.util.HashMap; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern;
class GetIp{ public static void main(String[] args) throws IOException {
    Map<String,Integer>result = <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">new</span> HashMap<String,Integer>();
    
    String s = <span class="hljs-string" style="color: #ec7600;">"Aug 23 09:29:46 oracle205 sshd[222466]: Accepted password for root from 124.127.207.154 port 46955 ssh2"</span>;
    File f = <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">new</span> File(<span class="hljs-string" style="color: #ec7600;">"E:\\secure-20150830"</span>);
    GetIp.getfromFile(result,f);
    
    GetIp.print(result);
}

<span class="hljs-function"><span class="hljs-keyword" style="color: #93c763; font-weight: bold;">public</span> <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">static</span> <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">void</span> <span class="hljs-title" style="font-weight: bold;">print</span><span class="hljs-params">(Map<String,Integer>result)</span></span>{
    <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">for</span>(String ip:result.keySet()){
        System.out.println(ip+<span class="hljs-string" style="color: #ec7600;">"--"</span>+result.get(ip));
    }
}

<span class="hljs-function"><span class="hljs-keyword" style="color: #93c763; font-weight: bold;">public</span> <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">static</span> <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">void</span> <span class="hljs-title" style="font-weight: bold;">getfromFile</span><span class="hljs-params">(Map<String,Integer>result,File f)</span> <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">throws</span> IOException</span>{
    String regex = <span class="hljs-string" style="color: #ec7600;">"((2[0-4]\\d|25[0-5]|[01]?\\d\\d?)\\.){3}(2[0-4]\\d|25[0-5]|[01]?\\d\\d?)"</span>;
    Pattern pa = Pattern.compile(regex);
    BufferedReader br = <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">new</span> BufferedReader(<span class="hljs-keyword" style="color: #93c763; font-weight: bold;">new</span> FileReader(f));
    String line = <span class="hljs-string" style="color: #ec7600;">""</span>;
    <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">while</span>((line = br.readLine())!=<span class="hljs-keyword" style="color: #93c763; font-weight: bold;">null</span>){
        Matcher match = pa.matcher(line);
        <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">while</span>(match.find()){
            String x = match.group();
            <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">if</span>(result.containsKey(x)){
                result.put(x,result.get(x)+<span class="hljs-number" style="color: #ffcd22;">1</span>);
            }
            <span class="hljs-keyword" style="color: #93c763; font-weight: bold;">else</span>{
                result.put(x,<span class="hljs-number" style="color: #ffcd22;">1</span>);
            }
        }
    }
    br.close();
    
}
Map<String,<span class="hljs-number" style="color: #ffcd22;">1</span>);
            }
        }
    }
    br.close();
    
}}

python处理正则表达式

读取文件，并解析文件中的ip地址。

import re
author = 'hgfdo'
f = open(r"e:\secure",'r')
pattern = re.compile(r'(\d+).(\d+).(\d+).(\d+)') result = {}
for line in f.readlines(): match = pattern.search(line) if match: x = match.group() if x in result.keys(): result[x] = result[x] + 1 else: result[x] = 1
for x in result.keys(): print "%s --- %d" %(x,result[x])

注意：在java中使用的是Pattern.matcher(String),在String中搜索匹配的字符串（不管这个匹配是不是在字符串的起始位置），而python的match(string)只能匹配出在字符串起始位置的子字符串，若子字符串在字符串中间，则匹配不出，需要使用search(String)来匹配字符串中的子字符串。

贺广福(heguangfu)@2015-9-17