读取属性Weblogic Server时的NullpointerException

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class WeblogicConfigReader {
    private Properties properties;

    public WeblogicConfigReader(String configFilePath) {
        properties = new Properties();
        try (FileInputStream fis = new FileInputStream(configFilePath)) {
            properties.load(fis);
        } catch (IOException e) {
            System.err.println("Failed to load configuration file: " + configFilePath);
            e.printStackTrace();
        }
    }

    public String getProperty(String key) {
        if (properties != null && properties.containsKey(key)) {
            return properties.getProperty(key);
        }
        return null;
    }

    public static void main(String[] args) {
        WeblogicConfigReader reader = new WeblogicConfigReader("path/to/config.properties");
        String serverUrl = reader.getProperty("server.url");
        if (serverUrl != null) {
            System.out.println("Server URL: " + serverUrl);
        } else {
            System.out.println("Server URL not found in configuration.");
        }
    }
}