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JSP&Servlet路径问题

程序员文章站 2022-04-17 11:30:22
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2019独角兽企业重金招聘Python工程师标准>>> JSP&Servlet路径问题

如果带WebRoot，那么js、css、img都应该放到WebRoot目录下，否则访问会有问题。千万不要放在WEB-INF下，因为WEB-INF下的内容只有服务器转发可以访问到，出于安全考虑。

如果不带有WebRoot目录，那么可以放在WEB-INF外面（建立的文件夹中）。

一、JSP、Servlet中的相对路径

a) 在JSP中

“/”代表站点（服务器）根目录http://127.0.0.1/

b)     在Servlet中

“/”代表Web应用的根目录http://127.0.0.1/JSP_Servlet_Path/

request.getRequestDispatcher("/a/a.jsp").forward(request, response);

相对路径/a/a.jsp中/相对于web应用的根目录，所以相当于请求跳转到绝对路径

http://127.0.0.1/JSP_Servlet_Path/a/a.jsp

response.sendRedirect("/JSP_Servlet_Path/b/b.jsp");

因为重定向中的方法是传递给浏览器，用于重新发送请求的，而在浏览器端“/”代表，相对于站点根目录http://127.0.0.1/，所以这里必须要加上/JSP_Servlet_Path，这样浏览器重新请求的地址为：http://127.0.0.1/JSP_Servlet_Path/b/b.jsp 

package com.jsp_servlet_path.rqq;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class JSP_Servlet extends HttpServlet {
 
    @Override
    public voiddoGet(HttpServletRequest request, HttpServletResponse response)
                    throwsServletException, IOException {
                    
           doPost(request,response);
    }
 
    @Override
    public voiddoPost(HttpServletRequest request, HttpServletResponse response)
                        throwsServletException, IOException {
               System.out.println(request.getContextPath());
                //请求转发，在服务器端，"/"代表（相对于）web应用http://localhost:8000/JSP_Servlet_Path/
               //所以请求转发的绝对路径为http://localhost:8000/JSP_Servlet_Path/a/a.jsp
                // request.getRequestDispatcher("/a/a.jsp").forward(request,response);
               //请求重定向，将方法中的地址参数传递给浏览器，让浏览器重新发送请求，
               //"/"代表（相对于）服务器站点http://localhost:8000/
               //所以相当于浏览器重新请求了绝对路径http://localhost:8000/JSP_Servlet_Path/b/b.jsp
               response.sendRedirect("/JSP_Servlet_Path/b/b.jsp");
               //response.sendRedirect(request.getContextPath()+ "/b/b.jsp");
    }
}

二、JSP中加入basePath

<%
    String path = request.getContextPath();
    String basePath= request.getScheme()+"://"
        +request.getServerName()+":"
        +request.getServerPort()+path+"/";
%>
<head>
<base href="<%=basePath%>">

    注：相当于所有的href相对路径前面都加入了：

               http://localhost:8000/JSP_Servlet_Path/

三、JSP与Servlet相互访问

<?xmlversion="1.0"encoding="UTF-8"?>
<web-appversion="2.5"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
         http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
    <servlet-name>JSP_Servlet</servlet-name>
    <servlet-class>com.jsp_servlet_path.rqq.JSP_Servlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>CopyOfJSP_Servlet</servlet-name>
    <servlet-class>com.jsp_servlet_path.rqq.CopyOfJSP_Servlet</servlet-class>
  </servlet>
 
  <servlet-mapping>
    <servlet-name>JSP_Servlet</servlet-name>
    <url-pattern>/servlet/JSP_Servlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>CopyOfJSP_Servlet</servlet-name>
    <url-pattern>/servlet/CopyOfJSP_Servlet</url-pattern>
  </servlet-mapping>
 
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>
<%@ page language="java"import="java.util.*"pageEncoding="GBK"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
 
<!DOCTYPEHTMLPUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN">
<html>
  <head>
   <basehref="<%=basePath%>">
   
   <title>My JSP 'index.jsp' starting page</title>
         <metahttp-equiv="pragma"content="no-cache">
         <metahttp-equiv="cache-control"content="no-cache">
         <metahttp-equiv="expires"content="0">   
         <metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">
         <metahttp-equiv="description"content="This is my page">
         <!--
         <linkrel="stylesheet" type="text/css"href="styles.css">
         -->
  </head>
 
  <bodybackground="/JSP_Servlet_Path/img/main1.jpg">
   This is index.jsp page. <br>
   <%--href中隐含了basePath，因为<basehref="<%=basePath%>">--%>
   <ahref="a/a.jsp">a.jsp(a/a.jsp)</a><br/>
   <ahref="/JSP_Servlet_Path/a/a.jsp">a.jsp(/JSP_Servlet_Path/a/a.jsp)</a><br/>
   <ahref="a/c/c.jsp">c.jsp(a/c/c.jsp)</a><br/>
   <ahref="a/c/e/e.jsp">e.jsp(a/c/e/e.jsp)</a><br/>
   <imgsrc="/JSP_Servlet_Path/img/2012317253390833.jpg"><br/>
   <imgsrc="a/main1.jpg"><br/>
   <ahref="servlet/JSP_Servlet?i=0">JSP_Servlet(servlet/JSP_Servlet)</a>
<a href="/JSP_Servlet_Path/servlet/JSP_Servlet?i=0">
JSP_Servlet(/JSP_Servlet_Path/servlet/JSP_Servlet)</a><br/>
    <ahref="servlet/JSP_Servlet?i=100">请求JSP_Servlet，并转发给CopyOfJSP_Servlet</a>
  </body>
</html>
package com.jsp_servlet_path.rqq;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class JSP_Servlet extends HttpServlet {
 
    @Override
    public voiddoGet(HttpServletRequest request, HttpServletResponse response)
                    throwsServletException, IOException {
                    
           doPost(request,response);
    }
 
    @Override
    public voiddoPost(HttpServletRequest request, HttpServletResponse response)
                        throwsServletException, IOException {
            System.out.println(request.getContextPath());
            //请求转发，在服务器端，"/"代表（相对于）web应用http://localhost:8000/JSP_Servlet_Path/
            //所以请求转发的绝对路径为http://localhost:8000/JSP_Servlet_Path/a/a.jsp
            // request.getRequestDispatcher("/a/a.jsp").forward(request,response);
            //请求重定向，将方法中的地址参数传递给浏览器，让浏览器重新发送请求，
            //"/"代表（相对于）服务器站点http://localhost:8000/
            //所以相当于浏览器重新请求了绝对路径http://localhost:8000/JSP_Servlet_Path/b/b.jsp
            response.sendRedirect("/JSP_Servlet_Path/b/b.jsp");
            //response.sendRedirect(request.getContextPath()+ "/b/b.jsp");
             Stringstr_i = request.getParameter("i");
             int i =new Integer(str_i);
             switch(i) {
                    case 0:
                        request.getRequestDispatcher("/index.jsp").forward(request,response);
                        System.out.println("index.jsp");
                        break;
                    case 1:
                        request.getRequestDispatcher("/a/a.jsp").forward(request, response);
                        System.out.println("a.jsp");
                        break;
                    case 2:
                        request.getRequestDispatcher("/b/b.jsp").forward(request,response);
                        System.out.println("b.jsp");
                        break;
                    case 3:
                        request.getRequestDispatcher("/a/c/c.jsp").forward(request,response);
                        System.out.println("c.jsp");
                        break;
                    case 100:
                        request.getRequestDispatcher("/servlet/CopyOfJSP_Servlet").forward(request,response);
                        System.out.println("forward to CopyOfJSP_Servlet");
                        break;
                    default:
                        System.out.println("default");
                        return;
             }
    }
}


转载于:https://my.oschina.net/fairy1674/blog/549314

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