1.JSP内置对象
请求对象：request
输出对象：out
响应对象：response
应用程序对象：application
会话对象：session
页面上下文对象：pageContext
页面对象：page
配置对象：config
异常对象：exception
2.request对象的常用方法：
String getParameter(String name)：根据页面表单组件名称获取页面提交数据
String [ ] getParamterValues(String name):获取一组以相同 名称命名的表单组件 提交的数据
void setCharacterEncoding(String charset): 指定每个请求的编码，在调用request.getParameter()方法之前进行设定，可以用于解决中文乱码问题
RequestDispatcher getRequestDispatcher(String payh):返回一个javax.servlet.RequestDispacher对象，该对象的foeward()
index：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
String username = request.getParameter("username");
String password = request.getParameter("password");
if (username.equals("lps") && password.equals("lucky")) {
response.sendRedirect("welcome.jsp");
} else {
out.println("请检查用户名和密码是否正确！");
}
%>
</body>
</html>
controller：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="controller.jsp" method="post">
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="登录"></td>
</tr>
</table>
</form>
</body>
</html>
welcome：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>欢迎您，来到贵美！</h1>
</body>
</html>
方法用于转发请求