JavaWebServletConfig作用及原理分析讲解

public class ConfigServlet extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        // 设置请求头
        servletResponse.setContentType("text/html");
        PrintWriter writer = servletResponse.getWriter();
        // 获取本servlet的servletconfig
        ServletConfig config = this.getServletConfig();
        // 打印本config的真实对象名称
        writer.println("servletconfig: " + config.toString() + "<br>");
        // 获取当前servletconfig所管辖的servlet的名称
        String configName = config.getServletName();
        writer.println("名字是：" + configName);
    }
}

<servlet>
    <servlet-name>configServlet</servlet-name>
    <servlet-class>com.zhiyiyi.javaweb.servlet.ConfigServlet</servlet-class>
    <init-param>
        <param-name>user</param-name>
        <param-value>root</param-value>
    </init-param>
</servlet>

// 使用枚举的方法获取到所有参数名称
Enumeration<String> initParameterNames = config.getInitParameterNames();
// 迭代输出获取到的参数名称
while (initParameterNames.hasMoreElements()) {
    String name = initParameterNames.nextElement();
    writer.println(name + "<br>");
}
// 直接指定需要获取的参数名称，精准拿到value
String userName = config.getInitParameter("user");
writer.println(userName + "<br>");