如何在Java中使用java.regex.Matcher解析日志文件

Question

我试图理解Java中的正则表达式。 我正在玩Java中的日志文件，因此可以提取日志字段。 例如，我有以下一行：

Apr 10 21:08:55 kali sshd[37727]: Failed password for root from 127.0.0.1 port 42035 ssh2"

我想要这样的输出：

"Date&Time" = Apr 10 21:08:55
"Hostname" = kali
"Program Name" = sshd
"Log" = Failed password for root from 127.0.0.1 port 42035 ssh2

到目前为止，这是我的Java代码：

公共类LogRegExp {

public static void main(String argv[]) {
    String logEntryLine = "Apr 10 21:08:55 kali sshd[37727]: Failed password for root from 127.0.0.1 port 42035 ssh2";
    String logEntryPattern = "(\\w.+) (\\d.+) (\\w.+) (\\w.+)";

    Pattern p = Pattern.compile(logEntryPattern);
    Matcher matcher = p.matcher(logEntryLine);
    if (!matcher.matches()) {
        System.err.println("Bad log entry (or problem with RE?):");
        System.err.println(logEntryLine);
        return;
    }
    System.out.println("Date&Time: " + matcher.group(1));
        System.out.println("Hostname: " + matcher.group(2));
    System.out.println("Program Name: " + matcher.group(3));
        System.out.println("Log: " + matcher.group(4));

}

我尝试按照以下示例进行操作： http : //www.java2s.com/Code/Java/Development-Class/ParseanApachelogfilewithRegularExpressions.htm

但是我无法适应它的需求。 我知道如何应用esacape字符，数字等，但是我不知道如何适应我的情况。 谁能帮我吗？

Answer 1

使用此代码：

public class LogRegExp {

    public static void main(String argv[]) {
        String logEntryLine = "Apr 10 21:08:55 kali sshd[37727]: Failed password for root from 127.0.0.1 port 42035 ssh2";
        String logEntryPattern = "([\\w]+\\s[\\d]+\\s[\\d:]+)\\s([\\w]+)\\s([\\w]+)\\[.+\\]:\\s(.+)";

        Pattern p = Pattern.compile(logEntryPattern);
        Matcher matcher = p.matcher(logEntryLine);
        if (!matcher.matches()) {
            System.err.println("Bad log entry (or problem with RE?):");
            System.err.println(logEntryLine);
            return;
        }
        System.out.println("Date&Time: " + matcher.group(1));
        System.out.println("Hostname: " + matcher.group(2));
        System.out.println("Program Name: " + matcher.group(3));
        System.out.println("Log: " + matcher.group(4));

    }
}

Answer 2

您可以对代码进行以下修改：

public class LogRegExp {

    public static void main(String argv[]) {
        String logEntryLine = "Apr 10 21:08:55 kali sshd[37727]: Failed password for root from 127.0.0.1 port 42035 ssh2";
        String logEntryPattern = "([\\w]+\\s[\\d]+\\s[\\d:]+) (\\w+) (\\w{4})(\\[\\d{5}\\]:) (\\w.+)";

        Pattern p = Pattern.compile(logEntryPattern);
        Matcher matcher = p.matcher(logEntryLine);
        if (!matcher.matches()) {
            System.err.println("Bad log entry (or problem with RE?):");
            System.err.println(logEntryLine);
            return;
        }
        System.out.println("Date&Time: " + matcher.group(1));
        System.out.println("Hostname: " + matcher.group(2));
        System.out.println("Program Name: " + matcher.group(3));
        System.out.println("Log: " + matcher.group(5));

    }
}

该程序的输出为：

Date&Time: Apr 10 21:08:55
Hostname: kali
Program Name: sshd
Log: Failed password for root from 127.0.0.1 port 42035 ssh2

Answer 3

尝试使用以下模式：

String logEntryPattern = "(.+\\d\\d?:\\d\\d?:\\d\\d?) (\\S+) ([^\\[]+)\\S+ (.+)";
                                   hh::mm::ss