1.写网页有html,jsp，servlet.但是三者有各自的优缺点，html适合写一些静态的显示，jsp适合写动态可变的显示，servlet适合处理业务逻辑，分发转向，DAO数据中转。
2.本项目使用jsp+servlet来实现一个简单的网页注册和登录，需要一点jsp的语法基础，比如<% 插入java代码%>、<a herf=""></a>表示转发。form跟html一样表示表单。<!---- ----->表示注释。
<%! %>申明全局变量等基础的语法，还有几个指令page include taglib
3.建立一个web网页，默认生成一个web.xml文件。工程名为webServletTest 在java Resouces目录下建立一个webservlet.java。
package webJspDemo.com;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("/servlet/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()); //获取表单数据
response.setContentType("text/html; charset=UTF-8");
request.setCharacterEncoding("UTF-8");
String userName = request.getParameter("userName");
String pwd = request.getParameter("pwd"); if("tom".equals(userName)&&"123".equals(pwd)){
request.getSession().setAttribute("name", userName);
request.getRequestDispatcher("/register.jsp").forward(request, response);
}else{
request.setAttribute("msg", "用户名或者密码不正确");
request.getRequestDispatcher("/login.jsp").forward(request, response);
} //分发转向
} /**
* @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);
}
}4.修改web.xml的映射关系和类名
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>webJspDemo.com.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>5.在WEB-INF目录下建立3个jsp，分别为home.jsp、login.jsp、register.jsp文件。
home.jsp代码为
<body>
<h1>欢迎来到本站!</h1>
<%
String userName =(String)session.getAttribute("name");
out.print(userName);
%>
</body>login.jsp代码为：
<body>
<%
String msg = (String)request.getAttribute("msg");
if(msg !=null){
out.print(msg);
}
%>
<form action="/webJspDemo1/servlet/loginservlet" method="get">
用户名：<input type="text" name="userName"/><br/>
密码：<input type="password" name="pwd"/><br/>
<input type="submit" value="登录"/><br/>
</form></body>register.jsp代码为：
<body>
欢迎你登录: <%
String userName =(String)session.getAttribute("name");
out.print(userName);
%>
<a href="/webJspDemo1/home.jsp">跳到主页 </a></body>5.实验结果
在浏览器中输入：http://localhost:8080/webJspDemo1/login
在表单中输入tom和123之后就会跳转到register.jsp界面，然后在到home.jsp界面，基本上就完成一个简单的注册流程。
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