java - 如何从 .log 文件中删除某些列/元素？

Question

我想删除某些日志条目以解析文件。但是，在运行 BufferedReader 和其他导入的函数和库时，我使用 .replaceAll 方法运行的代码出现错误。我该如何删除“rule_uid:{C1336766-9489-4049-9817-50584D83A245};”而不会导致错误？

日志文件:

Jan 1 22:54:17 drop   %LOGSOURCE% >eth1 rule: 7; rule_uid: {C1336766-9489-4049-9817-50584D83A245};
Jan 1 22:54:22 drop   %LOGSOURCE% >eth1 rule: 7; rule_uid: {C1336766-9489-4049-9817-50584D83A245};
Jan 1 22:54:23 drop   %LOGSOURCE% >eth1 rule: 7; rule_uid: {C1336766-9489-4049-9817-50584D83A245};
Jan 1 22:54:41 drop   %LOGSOURCE% >eth1 rule: 7; rule_uid: {C1336766-9489-4049-9817-50584D83A245};

错误:

"Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal repetition near index 9
rule_uid: {C1336766-9489-4049-9817-50584D83A245};" (which is at the .replaceAll() method for rule_uid column)

代码:

try {
        File file = new    File("filename");
        BufferedReader reader = new BufferedReader(new FileReader(file));
        String line = "", oldtext = "";
        while ((line = reader.readLine()) != null) {
            oldtext += line + "\r\n";
        }
        reader.close();
        // replace a word in a file
        String newtext = oldtext.replaceAll("%LOGSOURCE% >eth1 rule: 7;", "");
        String newtext1 = oldtext.replaceAll("rule_uid: {C1336766-9489-4049-9817-50584D83A245};", "");

     //To replace a line in a file
        FileWriter writer = new FileWriter("newfilename");
        writer.write(newtext);
        writer.write(newtext1);
        writer.close();
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
}

Answer 1

第二次调用 replaceAll() 时，输入字符串中有特殊字符，这些字符被解释为正则表达式语法的一部分，而不是要替换的纯文本。一旦我在 IntelliJ 中转义了这些特殊字符，编译器错误就消失了。

改变这个:

String newtext = oldtext.replaceAll("%LOGSOURCE% >eth1 rule: 7;", "");
String newtext1 = oldtext.replaceAll("rule_uid: {C1336766-9489-4049-9817-50584D83A245};", "");

对此:

String newtext = oldtext.replaceAll("%LOGSOURCE% >eth1 rule: 7;", "");
String newtext1 = oldtext.replaceAll("rule_uid: \\{C1336766-9489-4049-9817-50584D83A245\\};", "");

我所做的只是用两个前导反斜杠来转义大括号，例如\\{

更新:

您的代码中还有其他一些逻辑问题。这是我建议您使用的完整代码:

try {
    File file = new File("filename");
    BufferedReader reader = new BufferedReader(new FileReader(file));
    String line = "", oldtext = "";
    while ((line = reader.readLine()) != null) {
        oldtext += line + "\r\n";
    }
    reader.close();

    // replace a word in a file
    oldtext = oldtext.replaceAll("%LOGSOURCE% >eth1 rule: 7;", "");
    oldtext = oldtext.replaceAll("rule_uid: \\{C1336766-9489-4049-9817-50584D83A245\\};", "");

    FileWriter writer = new FileWriter("newfilename");

    // the entire file is contained within the String 'oldtext'
    // you only need one write operation to output it
    writer.write(oldtext);
    writer.close();
} catch (IOException ioe) {
    ioe.printStackTrace();
}