System.out.println(System.getProperty("user.dir"));//user.dir指定了当前的路径 

File directory = new File("");//设定为当前文件夹 
try{ 
  System.out.println(directory.getCanonicalPath());//获取标准的路径 
  System.out.println(directory.getAbsolutePath());//获取绝对路径 
}catch(Exceptin e){} 

File directory = new File("abc"); 
directory.getCanonicalPath(); //得到的是C:/test/abc 
directory.getAbsolutePath();  //得到的是C:/test/abc 
direcotry.getPath();          //得到的是abc 

File directory = new File("."); 
directory.getCanonicalPath(); //得到的是C:/test 
directory.getAbsolutePath();  //得到的是C:/test/. 
direcotry.getPath();          //得到的是. 

File directory = new File(".."); 
directory.getCanonicalPath(); //得到的是C:/ 
directory.getAbsolutePath();  //得到的是C:/test/.. 
direcotry.getPath();          //得到的是.. 

# java.version                Java Runtime Environment version 
# java.vendor                Java Runtime Environment vendor 
# java.vendor.url              Java vendor URL 
# java.home                Java installation directory 
# java.vm.specification.version  Java Virtual Machine specification version 
# java.vm.specification.vendor  Java Virtual Machine specification vendor 
# java.vm.specification.name   Java Virtual Machine specification name 
# java.vm.version            Java Virtual Machine implementation version 
# java.vm.vendor            Java Virtual Machine implementation vendor 
# java.vm.name            Java Virtual Machine implementation name 
# java.specification.version    Java Runtime Environment specification version 
# java.specification.vendor     Java Runtime Environment specification vendor 
# java.specification.name      Java Runtime Environment specification name 
# java.class.version          Java class format version number 
# java.class.path           Java class path 
# java.library.path         List of paths to search when loading libraries 
# java.io.tmpdir            Default temp file path 
# java.compiler            Name of JIT compiler to use 
# java.ext.dirs            Path of extension directory or directories 
# os.name               Operating system name 
# os.arch                 Operating system architecture 
# os.version            Operating system version 
# file.separator             File separator ("/" on UNIX) 
# path.separator         Path separator (":" on UNIX) 
# line.separator            Line separator ("/n" on UNIX) 
# user.name            User's account name 
# user.home               User's home directory 
# user.dir                User's current working directory

request.getRequestURI() 

request.getContextPath() 

request.getServletPath() 

application.getRealPath("页面.jsp") 

absPath=new java.io.File(application.getRealPath(request.getRequestURI())).getParent(); 

Class.class.getClass().getResource("/").getPath() 

System.getProperty("user.dir") 

request.getSession().getServletContext().getRealPath("") 参数可具体到包名。 

request.getRequestURL() 

request.getRequestURI()