java里的路径

System.out.println(Thread.currentThread().getContextClassLoader().getResource(""));????

??? System.out.println(Main.class.getClassLoader().getResource(""));???????

??? System.out.println(ClassLoader.getSystemResource(""));???????
??? System.out.println(Main.class.getResource(""));???????
??? System.out.println(Main.class.getResource("/")); //Class文件所在路径?
??? System.out.println(new File("/").getAbsolutePath());???????
??? System.out.println(System.getProperty("user.dir"));??