java 的Class中获得相对路径，绝对路径的方法

import java.io.File;   
   
public class FileTest {   
    public static void main(String[] args) throws Exception {   
        System.out.println(Thread.currentThread().getContextClassLoader().getResource(""));   
   
        System.out.println(FileTest.class.getClassLoader().getResource(""));   
   
        System.out.println(ClassLoader.getSystemResource(""));   
        System.out.println(FileTest.class.getResource(""));   
        System.out.println(FileTest.class.getResource("/")); 
        //Class文件所在路径 
        System.out.println(new File("/").getAbsolutePath());   
        System.out.println(System.getProperty("user.dir"));   
    }   
}