1,在Servlet的配置文件中,可以使用一个或多个<init-param>标签为servlet配置一些初始化参数。
当servlet配置了初始化参数后,web容器在创建servlet实例对象时,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,将ServletConfig对象传递给servlet。进而,程序员通过ServletConfig对象就可以得到当前servlet的初始化参数信息。
代码:(为servlet配置初始化参数)
<servlet>
<servlet-name>ServletDemo8</servlet-name>
<servlet-class>cn.yujian.ServletDemo8</servlet-class>
<init-param>
<param-name>name</param-name>
<param-value>xxxx</param-value>
</init-param>
<init-param>
<param-name>charset</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>url</param-name>
<param-value>jdbc:mysql://localhost:3306/test</param-value>
</init-param>
<init-param>
<param-name>username</param-name>
<param-value>root</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value>root</param-value>
</init-param>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/...</param-value>
</init-param>
</servlet>
Java代码:(通过ServletConfig对象来获取servlet的初始化参数)
//servletConfig对象的使用
public class ServletDemo8 extends HttpServlet {
// 2.4
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
ServletConfig config = this.getServletConfig();
Enumeration e = config.getInitParameterNames();
while (e.hasMoreElements()) {
String name = (String) e.nextElement();
String value = config.getInitParameter(name);
System.out.println(name + "=" + value);
}
String url = config.getInitParameter("url");
String username = config.getInitParameter("username");
String password = config.getInitParameter("password");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
来源:oschina
链接:https://my.oschina.net/u/936286/blog/261738