java后台jsp Request获取url信息的各种方法比较

 从Request对象中可以获取各种路径信息，以下例子：
 假设请求的页面是index.jsp,项目是WebDemo，则在index.jsp中获取有关request对象的各种路径信息如下
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 String remoteAddress=request.getRemoteAddr();
 String servletPath=request.getServletPath();
 String realPath=request.getRealPath("/");
 String remoteUser=request.getRemoteUser();
 String requestURI=request.getRequestURI();
 out.println("path:"+path+"<br>");
 out.println("basePath:"+basePath+"<br>");
 out.println("remoteAddr:"+remoteAddress+"<br>");
 out.println("servletPath:"+servletPath+"<br>");
 out.println("realPath:"+realPath+"<br>");
 out.println("remoteUser:"+remoteUser+"<br>");
 out.println("requestURI:"+requestURI+"<br>");
 结果：
 path:/WebDemo
 basePath:http://localhost:8683/WebDemo/
 remoteAddr:127.0.0.1
 servletPath:/index.jsp
 realPath:D:\apache-tomcat-6.0.13\webapps\WebDemo\
 remoteUser:null
 requestURI:/WebDemo/index.jsp
 从上不难看出request各个对应方法所代表的含义

 从request获取各种路径总结：
 request.getRealPath("url");//虚拟目录映射为实际目录
 request.getRealPath("./");//网页所在的目录
 request.getRealPath("../");//网页所在目录的上一层目录
 假定你的web application(web应用)名称为news，你的浏览器中输入请求路径：http://localhost:8080/uploading/load.jsp
 request.getContextPath()  =>  /uploading
 request.getServletPath()  =>  /load.jsp
 request.getRequestURL()  =>  http://localhost:8080/uploading/load.jsp
 request.getRealPath("/")  =>   F:\learn\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\uploading\
 现在request.getRealPath("/") 这个方法已经不推荐使用了
 可以使用
 ServletContext.getRealPath(java.lang.String)  instead.
 request.getSession().getServletContext().getRealPath() 得到工程文件的实际物理路径,也就是绝对地址

       //Returns the part of this request's URL from the protocol name up to the query string in the first line of the HTTP request
          //  eg.     /manage/editExam.domethod=goExamSet&type=U
       String url = request.getRequestURI();
       //The returned URL contains a protocol, server name, port number, and server path, but it does not include query string parameters
         //eg.      http://127.0.0.1:8080/manage/editExam.domethod=goExamSet&type=U
       StringBuffer url_buffer = request.getRequestURL();
   HttpServletRequest 的这两种方法都只能得到不包含参数的请求url，区别如下：
 1 前者返回相对路径，后者返回完整路径
 2 前者返回string ，后者返回stringbuffer
 得到完整请求url可以通过如下方法，getQueryString()得到的是url后面的参数串，和前者相加就是带参数的请求路径了
   String queryString = request.getQueryString();
 ring fullPath = url + queryString;   // 或者是url_buffer.toString()+queryString;

借鉴地址：http://www.cnblogs.com/zhwl/p/3625360.html