ServletConfig讲解

 1 <servlet>
 2     <servlet-name>ServletConfigDemo1</servlet-name>
 3     <servlet-class>gacl.servlet.study.ServletConfigDemo1</servlet-class>
 4     <!--配置ServletConfigDemo1的初始化参数 -->
 5     <init-param>
 6         <param-name>name</param-name>
 7         <param-value>gacl</param-value>
 8     </init-param>
 9      <init-param>
10         <param-name>password</param-name>
11         <param-value>123</param-value>
12     </init-param>
13     <init-param>
14         <param-name>charset</param-name>
15         <param-value>UTF-8</param-value>
16     </init-param>
17 </servlet>

 1 package gacl.servlet.study;
 2 
 3 import java.io.IOException;
 4 import java.util.Enumeration;
 5 import javax.servlet.ServletConfig;
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 public class ServletConfigDemo1 extends HttpServlet {
12 
13     /**
14      * 定义ServletConfig对象来接收配置的初始化参数
15      */
16     private ServletConfig config;
17     
18     /**
19      * 当servlet配置了初始化参数后，web容器在创建servlet实例对象时，
20      * 会自动将这些初始化参数封装到ServletConfig对象中，并在调用servlet的init方法时，
21      * 将ServletConfig对象传递给servlet。进而，程序员通过ServletConfig对象就可以
22      * 得到当前servlet的初始化参数信息。
23      */
24     @Override
25     public void init(ServletConfig config) throws ServletException {
26         this.config = config;
27     }
28 
29     public void doGet(HttpServletRequest request, HttpServletResponse response)
30             throws ServletException, IOException {
31         //获取在web.xml中配置的初始化参数
32         String paramVal = this.config.getInitParameter("name");//获取指定的初始化参数
33         response.getWriter().print(paramVal);
34         
35         response.getWriter().print("<hr/>");
36         //获取所有的初始化参数
37         Enumeration<String> e = config.getInitParameterNames();
38         while(e.hasMoreElements()){
39             String name = e.nextElement();
40             String value = config.getInitParameter(name);
41             response.getWriter().print(name + "=" + value + "<br/>");
42         }
43     }
44 
45     public void doPost(HttpServletRequest request, HttpServletResponse response)
46             throws ServletException, IOException {
47         this.doGet(request, response);
48     }
49 
50 }