EraseSensitiveDataConverter.java

import org.apache.logging.log4j.core.pattern.LogEventPatternConverter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@Plugin(name = "EraseSensitiveData", category = "Converter")
@ConverterKeys({ "msg" })
public class EraseSensitiveDataConverter extends LogEventPatternConverter {

    private static final String NAME = "msg";
    private static final String JSON_REPLACEMENT_REGEX_1 = "\"$1\":\"٩(◕‿◕｡)۶\"";
    private static final String JSON_REPLACEMENT_REGEX_2 = "\"$1\":\"(づ ◕‿◕ )づ\"";  
    private static final String JSON_KEYS = "sensitive1|sensitive2"
    private static final Pattern JSON_PATTERN = Pattern.compile(/"(${JSON_KEYS})": "([^"]+)"/)

    public EraseSensitiveDataConverter(String[] options) {
        super(NAME, NAME); // What !?
    }

    public static EraseSensitiveDataConverter newInstance(final String[] options) {
        return new EraseSensitiveDataConverter(options);
    }

    @Override
    public void  format(LogEvent logEvent, StringBuilder outputMsg) {
        Message message = logEvent.getMessage();
        Message outMessage = new ParameterizedMessage(message.getFormattedMessage(),
                message.getParameters(),
                message.getThrowable());
        outputMsg.append(this.converter(outMessage.getFormat()));
    }
    
    private String converter(String message) {
        StringBuffer buffer = new StringBuffer();
        Matcher matcher = JSON_PATTERN.matcher(message);
        int i = 1;
        while (matcher.find()) {
            matcher.appendReplacement(buffer, i%2==0 ? JSON_REPLACEMENT_REGEX_1 : JSON_REPLACEMENT_REGEX_2);
          i++;
        }
        matcher.appendTail(buffer);
        return buffer.toString();
    }
}