servlet-获取web.xml配置的init-param参数

最新推荐文章于 2022-11-12 07:50:53 发布

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最新推荐文章于 2022-11-12 07:50:53 发布

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文章标签： web.xml java 数据库

原文链接：http://www.cnblogs.com/luoxiaozhao/p/6963824.html

本文介绍如何在web.xml中配置servlet及其初始化参数，并通过doGet方法读取这些参数来连接数据库，展示了一个具体的例子，包括连接数据库、查询数据并返回HTML格式结果的过程。

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1.web.xml配置的参数

 1      <servlet>
 2         <servlet-name>firstServlet</servlet-name>
 3         <servlet-class>com.Conservlet</servlet-class>
 4         <init-param>
 5             <param-name>url</param-name>
 6             <param-value>jdbc:mysql://localhost:3306/house</param-value>
 7         </init-param>
 8         <init-param>
 9             <param-name>user</param-name>
10             <param-value>root</param-value>
11         </init-param>
12         <init-param>
13             <param-name>pwd</param-name>
14             <param-value>123456</param-value>
15         </init-param>
16         <init-param>
17             <param-name>driver</param-name>
18             <param-value>com.mysql.jdbc.Driver</param-value>
19         </init-param>
20     </servlet>
21     <servlet-mapping>
22         <servlet-name>firstServlet</servlet-name>
23         <url-pattern>/a</url-pattern>
24     </servlet-mapping>

2.servlet的doGet()获取值

 1 protected void doGet(HttpServletRequest request, HttpServletResponse response)
 2             throws ServletException, IOException {
 3             // TODO Auto-generated method stub
 4             try {            
 5             ServletConfig config = getServletConfig();
 6             String driver=config.getInitParameter("driver");
 7             String url=config.getInitParameter("url");
 8             String user=config.getInitParameter("user");
 9             String pwd=config.getInitParameter("pwd");
10             response.setCharacterEncoding("gbk");
11             //注册驱动
12             Class.forName(driver);
13             //建立连接
14             Connection conn = (Connection)DriverManager.getConnection(url, user, pwd);
15             Statement stm = (Statement)conn.createStatement();
16             ResultSet rs = stm.executeQuery("select username,pwd from user");
17             response.setContentType("text/html;charset=gbk");
18             PrintStream out = new PrintStream(response.getOutputStream());
19             out.println("<html>");
20             out.println("<head>");
21             out.println("<title>测试连接</title>");
22             out.println("</head>");
23             out.println("<body>");
24             out.println("<table border=\"1\" width=\"300\"");
25             while(rs.next())
26             {
27                 out.println("<tr>");
28                 out.println("<td>"+rs.getString(1)+"</td>");
29                 out.println("<td>"+rs.getString(2)+"</td>");
30                 out.println("</tr>");
31             }    
32             out.println("</table>");
33             out.println("</body>");
34             out.println("</html>");
35         } catch (Exception e) {
36             // TODO: handle exception
37         }
38     }