五、ServletConfig

一、作用

　　ServletConfig对象是Servlet的专属配置对象，每个Servlet都单独拥有一个ServletConfig对象，用来获取web.xml中的配置信息。

二、使用：

获取ServletConfig对象：

• 获取ServletConfig对象：ServletConfig sg = this.getServletConfig();

• 获取web.xml中的属性配置：sg.getInitParameter(name)

public class TestServletConfig extends HttpServlet {
    @Override    
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //获取ServletConfig对象
            ServletConfig sg = this.getServletConfig();
        //设置请求编码格式
            req.setCharacterEncoding(sg.getInitParameter("code"));
        //设置响应编码格式
            resp.setContentType("text/html;charset=utf-8");
        //获取请求信息
            //获取web.xml中的属性配置
            String flag = sg.getInitParameter("flag");
            System.out.println(flag);
            //获取用户请求信息
            String uname=req.getParameter("uname");
        //处理请求信息
            System.out.println(uname);
        //响应处理结果
    }
}

web.xml中servlet的配置信息

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>11-ServletConfig</display-name>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServletConfig</servlet-name>
    <servlet-class>com.bjsxt.servlet.TestServletConfig</servlet-class>
    <!-- 配置当前Servlet的属性信息 -->
    <init-param>
        <param-name>flag</param-name>
        <param-value>true</param-value>
    </init-param>
     <init-param>
        <param-name>code</param-name>
        <param-value>utf-8</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>TestServletConfig</servlet-name>
    <url-pattern>/tg</url-pattern>
  </servlet-mapping>

</web-app>