1、我们来试着向一个servlet提交一个表单，现在webcontent下新建一个login.html页面，其中action对应servelt类名,代码如下：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8"> <title>提交表单</title> </head> <body> <form action="LoginServlet" method="post"> 用户名：<input name="username" type="text"><br> 密码：<input name="password" type="password"><br> <input value="提交" name="submit" type="submit"> </form> </body> </html>
附：request.getParameter("username");可以读取用户名输入框的值，针对复选框需要调用request.getParameterValues(name);将返回一个字符串数组
2、新建一个servlet类LoginServlet，代码如下：
package servletdemo; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * Servlet implementation class LoginServlet */ @WebServlet("/LoginServlet") public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public LoginServlet() { System.out.print("loginservlet..."); // TODO Auto-generated constructor stub } @Override public void init() throws ServletException { // TODO 自动生成的方法存根 System.out.print("init..."); } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.print("doget..."); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.print("dopost..."); } @Override public void destroy() { // TODO 自动生成的方法存根 System.out.print("destory..."); } }
注意：右键新建一个servlet不会在web.xml生成对应的配置标签，是因为servlet类里已经有了@WebServlet注解
3、运行login.html，可以验证servlet的生命周期，效果如下：
4、有时候需要获得web.xml里一些配置信息，例如下面的配置，其中name相当于key，value就是对应的值
<context-param>
<param-name>henry</param-name>
<param-value>123</param-value>
</context-param>
用这行代码就可以获得KEY对应的值：String result=this.getServletContext().getInitParameter("henry");
5、servlet在MVC中相当于controller，所以经常需要做一些页面的跳转，下面来看看页面导航的实现
- 请求重定向
直接跳转到其他的网站，response.sendRedirect("http://www.baidu.com");
- 请求包含
就是跳转到另外一个serlvet，但是也输出本servlet的内容，具体看例子
//需要跳转的servlet的doGet()方法 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub PrintWriter out=response.getWriter(); out.print("<h1>LoginServlet</h1>"); request.getRequestDispatcher("MyServlet").include(request, response); } //跳转到的MyServlet的doGet()方法 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO 自动生成的方法存根 String result=this.getServletContext().getInitParameter("henry"); System.out.print(result); resp.setContentType("text/html;charset=gbk"); PrintWriter pw=resp.getWriter(); pw.write(result); pw.close(); }
- 请求跳转
也是跳转到另外一个servlet，但是不输出本servlet的内容
//需要跳转的servlet的doGet()方法 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub PrintWriter out=response.getWriter(); out.print("<h1>LoginServlet</h1>"); request.getRequestDispatcher("MyServlet").forward(request, response); } //跳转到的MyServlet的doGet()方法 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO 自动生成的方法存根 String result=this.getServletContext().getInitParameter("henry"); System.out.print(result); resp.setContentType("text/html;charset=gbk"); PrintWriter pw=resp.getWriter(); pw.write(result); pw.close(); }
注意：getRequestDispatcher()方法的参数不是servlet类名，而是web.xml里url-pattern节点中的值
