JavaWeb核心之Servlet
1、Servlet
Servleta是运行在服务器端的小程序是sun公司提供的规范接口。用来处理客户端的请求、响应给浏览器的动态资源
2、Servlet 快速入门
(1)Servlet 实现步骤:
--------------------创建类实现Servlet接口
--------------------覆盖(重写)Service方法
--------------------在web.xml中就行servle配置
创建类实现Servlet接口:
覆盖(重写)Service方法
package demo01; import java.io.IOException; import javax.servlet.Servlet; import javax.servlet.ServletConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; public class QuickServlet implements Servlet { @Override public ServletConfig getServletConfig() { // TODO Auto-generated method stub return null; } @Override public String getServletInfo() { // TODO Auto-generated method stub return null; } @Override public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException { arg1.getWriter().write("service方法正在执行"); System.out.println("service方法正在执行"); } @Override public void destroy() { // TODO Auto-generated method stub System.out.println("destroy方法正在执行"); } @Override public void init(ServletConfig arg0) throws ServletException { // ServletConfig封装的是该Servlet在web.xml里面的配置 //获取Servlet名称 System.out.println(arg0.getServletName()); //获取ServletContext对象 ServletContext s=arg0.getServletContext(); System.out.println("init方法正在执行"); } }
在web.xml中就行servle配置
<?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>WEB04</display-name> <servlet> <servlet-name>abc</servlet-name>=================和下面必须一样 <servlet-class>demo01.QuickServlet</servlet-class>/===============路径/ <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>abc</servlet-name>==============随便写 <url-pattern>/aaa</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <description></description> <display-name>Servlet</display-name> <servlet-name>Servlet</servlet-name> <servlet-class>demo02.Servlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>Servlet</servlet-name> <url-pattern>/Servlet</url-pattern> </servlet-mapping> <servlet> <description></description> <display-name>Servlet01</display-name> <servlet-name>Servlet01</servlet-name> <servlet-class>demo02.Servlet01</servlet-class> </servlet> <servlet-mapping> <servlet-name>Servlet01</servlet-name> <url-pattern>/Servlet01</url-pattern> </servlet-mapping> </web-app>
创建类继承HttpServlet
实现步骤:
1)创建类继承HttpServlet类
2)覆盖doGet和doPost
3)在web.xml中进行servlet的配置
访问过程:
3、Servlet的API(生命周期)
(1)Servlet接口中的方法
1)init(ServletConfig config)
何时执行:servlet对象创建的时候执行
ServletConfig : 代表的是该servlet对象的配置信息
2)service(ServletRequest request,ServletResponse response)
何时执行:每次请求都会执行
ServletRequest :代表请求 认为ServletRequest 内部封装的是 http请求的信息
ServletResponse :代表响应 认为要封装的是响应的信息
3)destroy()
何时执行:servlet销毁(服务器关闭)的时候执行
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