编程那点事
我们对上一个例子进行修改，将响应的结果告诉前端的用户，通常是通过req.setAttribute(“消息名称”, “消息内容”);，然后页面使用${消息名称}就能取到值。
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 获得用户名
String userName = req.getParameter("userName");
// 获得密码
String userPassword = req.getParameter("userPassword");
if (userName.equals("admin") && userPassword.equals("123456")) {
// 把结果保存到请求中
req.setAttribute("message", "验证通过");
} else {
// 把结果保存到请求中
req.setAttribute("message", "验证失败");
}
// 转向
req.getRequestDispatcher("index.jsp").forward(req, resp);
}
}<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>index</title>
</head>
<body>
${message}
<form action="/login" method="post">
用户名：<input type="text" name="userName" /><br>
密码：<input type="password" name="userPassword" /><br>
<input type="submit" value="提交" />
</form>
</body>
</html>我输入的是用户名是admin，密码是123456，测试结果如下：
