JSP数据交互(一)

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