Servlet编程笔记

使用纯文本方式的编程方式略过。

下面利用MyEclipse和Dreamweaver这两个开发工具，设计一张调查统计，并显示调查结果。

相关知识点：Servlet获取表单参数

1.新建一个Web工程。

clip_image001

2.在Dreamweaver中，新建一个html页面，叫做survey.html。

image

右边红框内，是表示这些内容在form表单中。

设置各自input控件的名字。

同一组空间（如年龄）的name设置为相同。

注意：我这个版本的Dreamweaver中，在form属性中，会自动添加enctype= "multipart/form-data " 属性，这会导致后面出现严重错误，我排查了很久才找到。后面错误为：request.getParameter(name)这个方法中，获取的参数永远为null值。

HTML代码如下：

   1: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   2: <html xmlns="http://www.w3.org/1999/xhtml">
   3: <head>
   4: <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
   5: <title>无标题文档</title>
   6: </head>
   7:  
   8: <body>
   9: <p>网络调查表</p>
  10: <form action="webProject2/servlet/survey" method="post" enctype="multipart/form-data" name="form1" id="form1">
  11:   <table width="504" border="0">
  12:     <tr>
  13:       <td width="138">姓名：</td>
  14:       <td width="356"><label for="name"></label>
  15:       <input name="name" type="text" id="name" size="20" /></td>
  16:     </tr>
  17:     <tr>
  18:       <td>Email：</td>
  19:       <td><label for="email"></label>
  20:       <input name="email" type="text" id="email" size="40" /></td>
  21:     </tr>
  22:     <tr>
  23:       <td>年龄：</td>
  24:       <td><input type="radio" name="age" id="radio" value="18" />
  25:         小于18
  26:           <input name="age" type="radio" id="radio2" value="18-40" checked="checked" />
  27:         <label for="age"></label>
  28:         18-40
  29:         <input type="radio" name="age" id="radio3" value="40" />
  30:         <label for="age">大于40</label></td>
  31:     </tr>
  32:     <tr>
  33:       <td>编程时间：</td>
  34:       <td><label for="code"></label>
  35:         <select name="code" id="code">
  36:           <option value="never">不编程</option>
  37:           <option value="6" selected="selected">小于6个月</option>
  38:           <option value="6-12">6到12个月</option>
  39:           <option value="12-24">12-24个月</option>
  40:           <option value="24">大于24个月</option>
  41:       </select></td>
  42:     </tr>
  43:     <tr>
  44:       <td>操作系统：</td>
  45:       <td><label for="system"></label>
  46:         <select name="system" size="4" multiple="multiple" id="system">
  47:           <option value="winxp" selected="selected">Windows XP</option>
  48:           <option value="win7">Windows 7</option>
  49:           <option value="maxos">Max OS</option>
  50:           <option value="liunx">Liunx</option>
  51:       </select></td>
  52:     </tr>
  53:     <tr>
  54:       <td>编程语言：</td>
  55:       <td><input name="language" type="checkbox" id="language" value="java" />
  56:         Java
  57:       <label for="language"></label>
  58:       <input name="language" type="checkbox" id="language" value="c" />
  59:       C
  60:       <label for="language"></label>
  61:       <input name="language" type="checkbox" id="language" value="c++" />
  62:       C++
  63:       <label for="language"></label>
  64:       <input name="language" type="checkbox" id="language" value="cshape" />
  65:       C#
  66:       <label for="language"></label>
  67:       <input name="language" type="checkbox" id="language" value="vb" />
  68:       <label for="language">VB</label></td>
  69:     </tr>
  70:     <tr>
  71:       <td>建议：</td>
  72:       <td><label for="sugestion"></label>
  73:         <label for="comment"></label>
  74:       <textarea name="comment" id="comment" cols="45" rows="4"></textarea></td>
  75:     </tr>
  76:     <tr>
  77:       <td><input type="submit" name="submit" id="submit" value="提交" /></td>
  78:       <td><input type="reset" name="reset" id="reset" value="重置" /></td>
  79:     </tr>
  80:     <tr>
  81:       <td>&nbsp;</td>
  82:       <td><label for="textfield"></label></td>
  83:     </tr>
  84:     <tr>
  85:       <td>&nbsp;</td>
  86:       <td>&nbsp;</td>
  87:     </tr>
  88:   </table>
  89: </form>
  90: <p>&nbsp;</p>
  91: </body>
  92: </html>

 

3.在webProject2中添加Servlet类，并选择重构doPost()和doGet()方法。

注意点：

1.将输入的html设置为utf-8编码。

   1: response.setContentType("text/html;charset=utf-8");

2.将获取的request设置为utf-8编码

   1: request.setCharacterEncoding("utf-8");

3.使用request.getParameter(name)方法获取单个值的控件的值。

   1: request.getParameter("age")

4.使用request.getParameterValues(name)方法获取多个值的空间的值

   1: request.getParameterValues("system");

 

5.对用户输入框的内容进行内容过滤，防止js代码并使换行生效。

防止js代码：对<,>,’,”, ，&等进行替换。

   1: value = value.replace("&", "&amp;");
   2: value = value.replace("<", "&lt;");
   3: value = value.replace(">", "&gt;");
   4: value = value.replace(" ", "&nbsp;");
   5: value = value.replace("'", "&#39;");
   6: value = value.replace("\"", "&quot;");

使得换行生效：将\n换位<br />

   1: value = value.replace("\n", "<br />");

6.结尾处关闭数据流（系统已自动生成）：

   1: out.flush();
   2: out.close();

7.防止多选框未作选择的错误，加一个异常处理。

   1: try {
   2:         String[] language = request.getParameterValues("language");
   3:         for (String s : language) {
   4:             out.println("<li>" + s + "</li>");
   5:         }
   6:     } catch (Exception e) {
   7:         out.println("没有选择编程语言<br />");
   8:     }

参考代码：

   1: package jacob.practice;
   2:  
   3: import java.io.IOException;
   4: import java.io.PrintWriter;
   5: import java.util.Enumeration;
   6:  
   7: import javax.servlet.ServletException;
   8: import javax.servlet.http.HttpServlet;
   9: import javax.servlet.http.HttpServletRequest;
  10: import javax.servlet.http.HttpServletResponse;
  11:  
  12: public class SurveyServlet extends HttpServlet {
  13:  
  14:     /**
  15:      * The doGet method of the servlet. <br>
  16:      * 
  17:      * This method is called when a form has its tag value method equals to get.
  18:      * 
  19:      * @param request
  20:      *            the request send by the client to the server
  21:      * @param response
  22:      *            the response send by the server to the client
  23:      * @throws ServletException
  24:      *             if an error occurred
  25:      * @throws IOException
  26:      *             if an error occurred
  27:      */
  28:     public void doGet(HttpServletRequest request, HttpServletResponse response)
  29:             throws ServletException, IOException {
  30:  
  31:         doPost(request, response);
  32:     }
  33:  
  34:     /**
  35:      * The doPost method of the servlet. <br>
  36:      * 
  37:      * This method is called when a form has its tag value method equals to
  38:      * post.
  39:      * 
  40:      * @param request
  41:      *            the request send by the client to the server
  42:      * @param response
  43:      *            the response send by the server to the client
  44:      * @throws ServletException
  45:      *             if an error occurred
  46:      * @throws IOException
  47:      *             if an error occurred
  48:      */
  49:     public void doPost(HttpServletRequest request, HttpServletResponse response)
  50:             throws ServletException, IOException {
  51:  
  52:         response.setContentType("text/html;charset=utf-8");
  53:         PrintWriter out = response.getWriter();
  54:         out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
  55:         out.println("<HTML>");
  56:         out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
  57:         out.println("  <BODY>");
  58:         request.setCharacterEncoding("utf-8");
  59:         out.println("姓名：" + filterHtml(request.getParameter("name")) + "<br />");
  60:         out.println("Email：" + filterHtml(request.getParameter("email"))
  61:                 + "<br />");
  62:         out.println("年龄：" + request.getParameter("age") + "<br />");
  63:         out.println("编程时间：" + request.getParameter("code") + "<br />");
  64:         out.println("操作系统：<ul>");
  65:         String[] os = request.getParameterValues("system");
  66:         for (String s : os) {
  67:             out.println("<li>" + s + "</li>");
  68:         }
  69:         out.println("</ul><br />");
  70:         out.println("编程语言：<ul>");
  71:         try {
  72:             String[] language = request.getParameterValues("language");
  73:             for (String s : language) {
  74:                 out.println("<li>" + s + "</li>");
  75:             }
  76:         } catch (Exception e) {
  77:             out.println("没有选择编程语言<br />");
  78:         }
  79:  
  80:         out.println("</ul><br />");
  81:         out.println("建议：" + filterHtml(request.getParameter("comment"))
  82:                 + "<br />");
  83:         out.println("  </BODY>");
  84:         out.println("</HTML>");
  85:         out.flush();
  86:         out.close();
  87:     }
  88:  
  89:     public String filterHtml(String value) {
  90:         value = value.replace("&", "&amp;");
  91:         value = value.replace("<", "&lt;");
  92:         value = value.replace(">", "&gt;");
  93:         value = value.replace(" ", "&nbsp;");
  94:         value = value.replace("'", "&#39;");
  95:         value = value.replace("\"", "&quot;");
  96:         value = value.replace("\n", "<br />");
  97:         return value;
  98:  
  99:     }
 100:  
 101: }

4.部署。

启动Tomcat并部署。

5.运行。

在浏览器中输入http://localhost/webProject2/servlet/survey.html（这个根据自己设置的路径，参见web.xml这个文件）。

HTML页面：

image

统计界面：

image

posted @ 2012-04-16 14:18  等过了悲伤  阅读(239)  评论(0)  编辑  收藏  举报