File f=new File("xxxx");
      f.getAbsolutePath();

------解决方案--------------------
File f=new File("xxxx");
     String path=f.getAbsolutePath();
       try {
			FileWriter fw =new FileWriter("C:\\filename");
			fw.append(path+'\n');
			fw.flush();
			fw.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}