Servlet3规范目录结构

深碍√TFBOYSˉ_ 2023-06-30 10:44 5阅读 0赞

平台的目录结构如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JvYm96YWk4Ng_size_16_color_FFFFFF_t_70][]

把静态资源、jsp等信息全部放到resources/META-INF目录下，这块不是很理解，我之前都是放到webapp/WEB-INF目录下，这样不能通过url直接访问，网上查看到一片博客讲的比较清楚，记录如下：

在Servlet3协议规范中,包含在JAR文件/META-INFO/resources/路径下的资源可以直接访问了。这么说一说，可能感觉不到到底有什么好处，以往的JSP或者HTML页面只能存在站点的目录下，或者在WEB-INF目录下（只是不能直接访问）。

规范说，$\{jar\}/META-INF/resources/被视为根目录，假设home.jsp被放在$\{jar\}/META-INF/resources/home.jsp，用户可以直接通过 http://域名/home.jsp 访问了。

呈现一个常见的代码片段：

/**
     * 简单示范
     * @author yongboy  
     * @date 2011-1-16
     * @version 1.0
     */
    @WebServlet("/jarHome")
    public class HelloJarServlet extends HttpServlet {
     private static final long serialVersionUID = 6177346686921106540L;
    
     protected void doGet(HttpServletRequest request,
       HttpServletResponse response) throws ServletException, IOException {
      request.setAttribute("date", new Date());
      request.getRequestDispatcher("/jarpage/jarhome.jsp").forward(request, response);
     }
    }

而jarhome.jsp文件路径则位于 $\{jar\}/META-INF/resources/jarpage/jarhome.jsp，当然jarhome.jsp文件则没有什么特别之处：

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <link rel="stylesheet" href="css/style.css" type="text/css" />
    <title>Welcome to jar home</title>
    </head>
    <body>
    <img alt="j2ee" src="img/j2ee.png" /><br/>
    <br/>
    now date : <%=((java.util.Date)request.getAttribute("date")).toString()%>
    </body>
    </html>

jarhome.jsp文件所引用css/style.css和img/j2ee.png等文件分别位于 **$\{jar\}/META-INF/resources/css/style.css**和**$\{jar\}/META-INF/resources/img/j2ee.png**目录下。把生成的jar文件存放在 WEB-INF/lib/ 中，下面为一个运行示范图：

样式和图片等都可以正常访问。有时候可能需要使用路径信息等，再看一个示范吧：

/**
     * 演示jarDemo
     * 
     * @author yongboy
     * @date 2011-1-16
     * @version 1.0
     */
    @WebServlet("/jarDemo")
    public class DemoWebINFPagesServlet extends HttpServlet {
     private static final long serialVersionUID = -1040850432869481349L;
     private static final Log log = LogFactory
       .getLog(DemoWebINFPagesServlet.class);
    
     @SuppressWarnings("deprecation")
     @Override
     protected void doGet(HttpServletRequest request,
       HttpServletResponse response) throws ServletException, IOException {
      log.info("the /jarDemo is accessed now!");
    
      log.info("getRealPath : " + request.getRealPath("/"));
      log.info("ServletContext : getRealPath : "
        + getServletContext().getRealPath("/"));
      log.info("getPathTranslated : " + request.getPathTranslated());
    
      log.info("get jar's resource:");
    
      InputStream is = getServletContext().getResourceAsStream(
        "/jarfile/demo.txt");
      log.info("the JAR/META-INF/resources/jarfile/demo.txt's content is :\n"
        + IOUtils.toString(is));
    
      request.getRequestDispatcher("/WEB-INF/pages/notaccess.jsp");
     }
    }

输出命令行信息为：

[framework] 2011-01-03 11:45:16,664 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798292 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - the /jarDemo is accessed now!
    [framework] 2011-01-03 11:45:16,664 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798292 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - getRealPath : /home/yongboy/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/d/
    [framework] 2011-01-03 11:45:16,664 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798292 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - ServletContext : getRealPath : /home/yongboy/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/d/
    [framework] 2011-01-03 11:45:16,665 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798293 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - getPathTranslated : null
    [framework] 2011-01-03 11:45:16,665 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798293 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - get jar's resource:
    [framework] 2011-01-03 11:45:16,665 - com.learn.servlet3.jardync.DemoWebINFPagesServlet -798293 [http-8080-exec-6] INFO  com.learn.servlet3.jardync.DemoWebINFPagesServlet  - the ${JAR}/META-INF/resources/jarfile/demo.txt's content is :
    haha,the demo.s's content!
    haha,haha,haha!

可以看到getRealPath（"/"）得到的是项目的根路径（可以参照JAR解压后的路径）。而request.getPathTranslated则因为是包含在jar文件中（规范中说包含在远程主机、数据库、JAR存档文件中，getPathTranslated都会返回null），则返回null。

包含在jar中的资源文件，一样可以使用getResourceAsStream获取到。再来看看jar文件META-INF/resources目录下文件结构：

*  css/style.css
 *  img/j2ee.png
 *  jarfile/demo.txt
 *  jarpage/jarhome.jsp
 *  jsp/h.jsp
 *  jsp/helloWorld.jsp

很显然，就是一个小型站点目录结构。每一个模块，建立一个WEB站点应用，使用ANT脚本自动打包成jar文件，拷贝到真正站点WEB-INF/lib下。假设一个JAR文件包含一个具体的模块，那么模块的部署与装载将是十分方便的。

参考：

[https://openhome.cc/Gossip/ServletJSP/DirectoryStructure.html][https_openhome.cc_Gossip_ServletJSP_DirectoryStructure.html]

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[https_openhome.cc_Gossip_ServletJSP_DirectoryStructure.html]: https://openhome.cc/Gossip/ServletJSP/DirectoryStructure.html