我正在使用的一些字符串模式并没有在运行时获取匹配,而当我在线使用正则表达式检查程序(如Regular Expression Tester时)时,我看到我的模式会获取所需的输出。
public class RegexMatches
{
public static void main( String args[] ){
String input = "[1463895254]PING www.andi.dz (213.179.181.44) 100(128) bytes of data.[1463895254]108 bytes from 213.179.181.44: icmp_seq=1 ttl=54 time=195 ms[1463895255]108 bytes from 213.179.181.44: icmp_seq=2 ttl=54 time=202 ms[1463895256]108 bytes from 213.179.181.44: icmp_seq=3 ttl=54 time=180 ms[1463895257]108 bytes from 213.179.181.44: icmp_seq=4 ttl=54 time=200 ms[1463895258]108 bytes from 213.179.181.44: icmp_seq=5 ttl=54 time=206 ms[1463895259]108 bytes from 213.179.181.44: icmp_seq=6 ttl=54 time=188 ms[1463895260]108 bytes from 213.179.181.44: icmp_seq=7 ttl=54 time=182 ms[1463895261]108 bytes from 213.179.181.44: icmp_seq=8 ttl=54 time=223 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=9 ttl=54 time=187 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=10 ttl=54 time=199 ms";
try{
String op[] = parseIndividualIP(input);
System.out.println(op[1]);
System.out.println(op[8]);
}
catch (Exception e){
e.printStackTrace();
}
}
// Doesn't Work...
public static String[] parseIndividualIP(String input) throws IPAddressNotFoundException {
// Capture the ip-address after 'x byes from'
Pattern p = Pattern.compile("bytes\\s+from\\s+([\\d,\\.]+):");
Matcher m = p.matcher(input);
if (m.find()){
int i = 0;
String[] s = new String[10];
while(m.find()){
s[i] = m.group(++i);
}
return s;
}
else
throw new IPAddressNotFoundException();
}
}
我不知道为什么在运行时我没有匹配以及我应该如何调试此问题。由于模式在运行之前和之后进行了交叉检查。
输入字符串 -
[1463895254]PING www.andi.dz (213.179.181.44) 100(128) bytes of data.[1463895254]108 bytes from 213.179.181.44: icmp_seq=1 ttl=54 time=195 ms[1463895255]108 bytes from 213.179.181.44: icmp_seq=2 ttl=54 time=202 ms[1463895256]108 bytes from 213.179.181.44: icmp_seq=3 ttl=54 time=180 ms[1463895257]108 bytes from 213.179.181.44: icmp_seq=4 ttl=54 time=200 ms[1463895258]108 bytes from 213.179.181.44: icmp_seq=5 ttl=54 time=206 ms[1463895259]108 bytes from 213.179.181.44: icmp_seq=6 ttl=54 time=188 ms[1463895260]108 bytes from 213.179.181.44: icmp_seq=7 ttl=54 time=182 ms[1463895261]108 bytes from 213.179.181.44: icmp_seq=8 ttl=54 time=223 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=9 ttl=54 time=187 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=10 ttl=54 time=199 ms
使用正则表达式模式 -
bytes\\s+from\\s+([\\d,\\.]+):
答案 0 :(得分:1)
主要问题是使用m.group(++i)
。在正则表达式中,您有一个捕获组来捕获IP地址(([\\d,\\.]+)
),这意味着您应该调用m.group(1)
,因为它返回第一组捕获的字符串。
Pattern对象是线程安全的,因此可以编译一次并重复使用相同的实例。
以下代码包含组修复以及一些可读性修改。将数组的用法更改为链接列表,而不是抛出异常,方法返回,如果找不到匹配项,则返回空列表。
import java.util.LinkedList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexMatches {
private static final Pattern PATTERN = Pattern.compile("bytes\\s+from\\s+([\\d,\\.]+):");
public static void main(String args[]) {
String input = "[1463895254]PING www.andi.dz (213.179.181.44) 100(128) bytes of data.[1463895254]108 bytes from 213.179.181.44: icmp_seq=1 ttl=54 time=195 ms[1463895255]108 bytes from 213.179.181.44: icmp_seq=2 ttl=54 time=202 ms[1463895256]108 bytes from 213.179.181.44: icmp_seq=3 ttl=54 time=180 ms[1463895257]108 bytes from 213.179.181.44: icmp_seq=4 ttl=54 time=200 ms[1463895258]108 bytes from 213.179.181.44: icmp_seq=5 ttl=54 time=206 ms[1463895259]108 bytes from 213.179.181.44: icmp_seq=6 ttl=54 time=188 ms[1463895260]108 bytes from 213.179.181.44: icmp_seq=7 ttl=54 time=182 ms[1463895261]108 bytes from 213.179.181.44: icmp_seq=8 ttl=54 time=223 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=9 ttl=54 time=187 ms[1463895263]108 bytes from 213.179.181.44: icmp_seq=10 ttl=54 time=199 ms";
List<String> op = parseIndividualIP(input);
op.forEach(System.out::println);
}
public static List<String> parseIndividualIP(String input) {
Matcher m = PATTERN.matcher(input);
List<String> ips = new LinkedList<>();
while (m.find()) {
ips.add(m.group(1));
}
return ips;
}
}