Web应用中request获取path，URI，URL

Web应用中有各种获取path或URI，URL的方法，假设网页访问地址:

http://localhost:8080/tradeload/TestServlet

Web应用context: /tradeload 

各路径鉴定如下：

request.getContextPath()= /tradeload
request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()= http://localhost:8080
request.getRequestURL() = http://localhost:8080/tradeload/TestServlet
request.getRequestURI() = /tradeload/TestServlet
request.getPathInfo() = null
request.getServletPath() = /TestServlet
getServletContext().getRealPath('/') = C:serverglassfishdomainsdomain1applicationsj2ee-modules	radeload

其中的servletpath就是web.xml中配置的url-pattern。

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假定你的web application 名称为news,你在浏览器中输入请求路径： 
http://localhost:8080/news/main/list.jsp 
则执行下面向行代码后打印出如下结果：

1、System.out.println(request.getContextPath());

打印结果：/news

2、System.out.println(request.getServletPath());

打印结果：/main/list.jsp

3、System.out.println(request.getRequestURI());

打印结果：/news/main/list.jsp

4、System.out.println(request.getRealPath("/"));

打印结果：F:Tomcat 6.0webapps
ews	est

String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

out.println("basePath:"+basePath);
out.println("<br/>");
out.println("getContextPath:"+request.getContextPath());
out.println("<br/>");
out.println("getServletPath:"+request.getServletPath());
out.println("<br/>");
out.println("getRequestURI:"+request.getRequestURI());
out.println("<br/>");
out.println("getRequestURL:"+request.getRequestURL());
out.println("<br/>");
out.println("getRealPath:"+request.getRealPath("/"));
out.println("<br/>");
out.println("getServletContext().getRealPath:"+getServletContext().getRealPath("/"));
out.println("<br/>");
out.println("getQueryString:"+request.getQueryString());

显示结果：

basePath:http://localhost:8080/test/

getContextPath:/test
getServletPath:/test.jsp
getRequestURI:/test/test.jsp
getRequestURL:http://localhost:8080/test/test.jsp
getRealPath:D:Tomcat 6.0webapps est
getServletContext().getRealPath:D:Tomcat 6.0webapps est
getQueryString:p=fuck

在一些应用中，未登录用户请求了必须登录的资源时，提示用户登录，此时要记住用户访问的当前页面的URL，当他登录成功后根据记住的URL跳回用户最后访问的页面：

String lastAccessUrl = request.getRequestURL() + "?" + request.getQueryString();