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-6.0.13webappsWebDemo  
    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.pluginsorg.eclipse.wst.server.core	mp0wtpwebappsuploading  
    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;