Java Web登录
在Java Web项目中Servlet就相当于控制器,JSP就相当于视图。登录主要分为两部分,提交,判断。先将JSP中输入的用户名和密码提交到Servlet,再在Servlet中进行判断。
JSP的表单提交:
<body>
<form action="pageContext.request.contextPath/servlet/UserServlet" method="post">
用户名<input id="username" name="username">
密码<input id="password" name="password">
<button type="submit">登录</button>
</form>
</body>
Servlet的登录方法:
public void login (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//先获取JSP输入的用户名和密码
String username=request.getParameter("username");
String password=request.getParameter("password");
//声明对象
User user=null;
try {
//连接mysql数据库
Class.forName("com.mysql.jdbc.Driver");
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/user", "root", "root");
//发送sql语句
PreparedStatement ps=con.prepareStatement("select * from user where username=? and password=?");
//给PreparedStatement对象的占位符赋值
ps.setString(1, username);
ps.setString(2, password);
//执行语句
ResultSet rs=ps.executeQuery();
//通过while循环给对象参数赋值
while (rs.next()) {
user=new User();
user.setUserid(rs.getInt("userid"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//判断对象是否有值
if(user!=null){
System.out.println("登录成功");
}else{
System.out.println("用户名或密码错误");
}
}