Servlet：
1. 一种特殊的服务器端的java类,用来生成动态的html,所有会在java中写html。
2. 它担当客户请求（Web浏览器）与服务器响应（HTTP服务器上的数据库）的中间层。可理解为：Servlet接受用户请求，进行处理，需要的话和数据库交互，生成动态的html作为response返回
让我们使用Eclipse用servelt写一个最简单的动态登陆服务
关于如何准备环境可参考
1. 创建项目
2. 创建servlet
内容如下：
package loginServlet;
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() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
String username = request.getParameter("username");
String password = request.getParameter("password");
response.setContentType("text/html,charset=GB18030");
response.getWriter().println("<html>");
response.getWriter().println("<head>");
response.getWriter().println("<body>");
response.getWriter().println("</br>");
response.getWriter().println("Welcome "+ username + "!");
response.getWriter().println("</body>");
response.getWriter().println("</head>");
response.getWriter().println("</html>");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
3. 编写html
内容如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="http://localhost:8080/FirstServlet/LoginServlet" method="post">
username:<input type="text" name="username" /></br>
password:<input type="password" name="password" /></br>
<input type="submit" value="submit" />
</form>
</body>
</html>
4. 部署servlet
创建web.xml,内容如下：
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>loginServlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/FirstServlet/LoginServlet</url-pattern>
</servlet-mapping>
</web-app>
则执行项目：
启动服务器，然后访问提交
