JavaWeb基礎 繼承GenericServlet 簡單示例
阿新 • • 發佈:2017-10-22
tro cep link class exceptio app_id pts ase import
禮悟:
好好學習多思考,尊師重道存感恩。葉見尋根三二一,江河湖海同一體。
虛懷若谷良心主,願行無悔給最苦。讀書鍛煉強身心,誠勸且行且珍惜。
javaEE:7
javaSE:1.8
JSTL:1.2.2
server:tomcat 8.5
explorer:Firefox
os:windows7 x64
ide:MyEclipse 2017
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <servlet> <servlet-name>myGenericServlet</servlet-name> <servlet-class>jizuiku.web.servlet.MyGenericServlet</servlet-class><!-- 執行的是這個類 --> <init-param> <param-name>minNum</param-name> <param-value>10</param-value> </init-param> <init-param> <param-name>maxNum</param-name> <param-value>100</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>myGenericServlet</servlet-name> <!-- 兩個name 相應就好 --> <url-pattern>/MyGenericServletDemo</url-pattern><!-- 訪問的是這個路徑 --> </servlet-mapping> </web-app>
繼承GenericServlet的類的代碼
package jizuiku.web.servlet; import java.io.IOException; import javax.servlet.GenericServlet; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; /** * * * @author 給最苦 * @version V17.10.20 */ public class MyGenericServlet extends GenericServlet{ /** * */ private static final long serialVersionUID = 1L; @Override public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException { System.out.println("執行service()..."); } // 根據源代碼可以推出 ,要重寫的方法一定是 init() @Override public void init() throws ServletException { // TODO Auto-generated method stub System.out.println("你好,執行初始化程序"); } @Override public void destroy() { // TODO Auto-generated method stub System.out.println("執行destroy()..."); } }
效果
如上瀏覽器訪問指定頁面 一次,控制臺輸出信息發生如下變化
擴展
為什麽要重寫 無參數的init()方法?請看源代碼
/** * Called by the servlet container to indicate to a servlet that the servlet * is being placed into service. See {@link Servlet#init}. * <p> * This implementation stores the {@link ServletConfig} object it receives * from the servlet container for later use. When overriding this form of * the method, call <code>super.init(config)</code>. * * @param config * the <code>ServletConfig</code> object that contains * configuration information for this servlet * @exception ServletException * if an exception occurs that interrupts the servlet‘s * normal operation * @see UnavailableException */ @Override public void init(ServletConfig config) throws ServletException { this.config = config; this.init(); }
關於serialVersionUID的簡單介紹
網址:http://www.cnblogs.com/btdxqz/p/6806372.html
學習資源:itcast和itheima視頻庫。如果您有公開的資源,可以分享給我的話,用您的資源學習也可以。
博文是觀看視頻後,融入思考寫成的。博文好,是老師講得好。博文壞,是 給最苦 沒認真。
JavaWeb基礎 繼承GenericServlet 簡單示例