### Question:
PropertiesUtil { public final static String key(String key) { return System.getProperty(key); }  final static String key(String key); final static String GetValueByKey(String filePath, String key); final static Map<String, String> properties(InputStream in); final static Map<String, String> GetAllProperties(String filePath); final static void WriteProperties(String filePath, String pKey, String pValue); static Logger logger; }### Answer:
@Test @Ignore public void testKey() { System.out.println(System.getProperties()); System.out.println(PropertiesUtil.key("user.name")); System.out.println(PropertiesUtil.key("file.encoding")); }