jsp中路径的问题。。。

　　　　　　刚刚学jsp的时候都是从看别人的代码，模仿着做，但是这样也有看不懂的地方，这个相对路径和绝对路径就让我纠结了好久。。所以我自己弄了一个demo实验了一下，试验出结果了，但是不明白原理，纠结了一天，终于问别人知道了，最关键的是我自己看到“地址栏”才理解啊。。。所有不能离了题。先附上demo的代码：

　　　　index.jsp

<FORM  action="servlet/TiaoZhuanServlet" method="post">
          请输入内容：<input type="text" name="info">
          <input type="submit" value="提交">
          </FORM>

　　　　show.jsp:

    <%
                          String info=(String)request.getAttribute("info");
                   %>
                   <h3>info的内容是：<%=info%></h3>

web.xml:

 <servlet>
     <servlet-name>TiaoZhuanServlet</servlet-name>
     <servlet-class>org.gsh.wh.servlet.TiaoZhuanServlet</servlet-class>
   </servlet>
 
   <servlet-mapping>
     <servlet-name>TiaoZhuanServlet</servlet-name>
     <url-pattern>/servlet/TiaoZhuanServlet</url-pattern>
   </servlet-mapping>

servlet:

 public class TiaoZhuanServlet extends HttpServlet {
 
     private static final long serialVersionUID = 1L;
 
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         request.setCharacterEncoding("GBK");
         String info=request.getParameter("info");
         request    .setAttribute("info", info);
         request.getRequestDispatcher("show.jsp").forward(request, response);
     }
 
     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
                 this.doGet(request, response);
 
     }

web.xml中德配置<servlet>     <description>This is the description of my J2EE component</description>     <display-name>This is the display name of my J2EE component</display-name>     <servlet-name>TiaoZhuanServlet</servlet-name>     <servlet-class>org.gsh.wh.servlet.TiaoZhuanServlet</servlet-class>   </servlet>

<servlet-mapping>     <servlet-name>TiaoZhuanServlet</servlet-name>     <url-pattern>/servlet/TiaoZhuanServlet</url-pattern>   </servlet-mapping>  在加“/”和不加“/”的理解上是这样的：加了“/”就是绝对路径。而不加“/”就是相对路径 绝对路径：比如在“/show”,那么它会在http://localhost/Test2下面照“show.jsp”, 如果不加的话：就是相对路径：从http://localhost/Test2/servlet/TiaoZhuanServlet（a）往show.jsp跳转,相对a的话跳转后的就是： http://localhost/Test2/servlet/show.jsp此时肯定找不到show.jsp

而如果你的配置如下： <servlet>     <description>This is the description of my J2EE component</description>     <display-name>This is the display name of my J2EE component</display-name>     <servlet-name>TiaoZhuanServlet</servlet-name>     <servlet-class>org.gsh.wh.servlet.TiaoZhuanServlet</servlet-class>   </servlet>

<servlet-mapping>     <servlet-name>TiaoZhuanServlet</servlet-name>     <url-pattern>/TiaoZhuanServlet</url-pattern>   </servlet-mapping> 表单那 里的action="TiaoZhuanServlet",记得更改。

则相对路径是：http://localhost/Test2下面照“show.jsp”,而不加的话：依然跳转http://localhost/Test2/TiaoZhuanServlet 往"show.jsp"跳转，结果为：http://localhost/Test2/show.jsp，所以加和不加一样

demo的图片