java - 如何在 Java 中使用 java.regex.Matcher 解析日志文件

Question

我正在尝试理解 java 中的正则表达式。我正在用 java 处理日志文件，因此我可以提取日志字段。例如，我有以下行:

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(public)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));

}

我试着按照这个例子:http://www.java2s.com/Code/Java/Development-Class/ParseanApachelogfilewithRegularExpressions.htm

但我无法使其适应我的需要。我了解如何应用转义字符、数字等，但我不知道如何根据我的情况进行调整。谁能帮帮我？

Answer 1

使用这段代码:

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));

    }
}