out 对象
向客户端浏览器输出各种数据
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page buffer="10kb" %> <!-- 修改缓冲区大小 -->
<!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>
<%
out.println("thystar");
out.newLine();
out.println("123");
out.println("<br/>");
// 强制刷新服务器输出缓冲区里的数据,手动将缓冲区里的数据输出到客户端浏览器
//out.flush();
// 清空缓冲区；
//out.clearBuffer();
// 清空数据，但是不能喝flash方法一起用，否则抛出异常
out.clear();
// 获取当前缓冲区的大小 out对象的默认缓冲区大小8KB
out.println(out.getBufferSize());
out.println("<br/>");
// 获取当前缓冲区剩余字节的数目
out.println(out.getRemaining());
%>
</body>
</html>
request对象
封装来自客户端浏览器的各种信息， 如cookie，客户端IP
<%@ 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>
<input type="text" name="userName"/>
<input type="submit" name="submit"/>
</form>
<!-- 获取请求的方法名 -->
<%= request.getMethod()%><br/>
<!-- 获取请求的URI字符串 -->
<%= request.getRequestURI() %><br/>
<!-- 获取请求时的协议 -->
<%= request.getProtocol() %><br/>
<!-- 获取请求的服务器IP -->
<%= request.getServerName() %><br/>
<!-- 获取请求服务器的端口号 -->
<%= request.getServerPort() %><br/>
<!-- 获取客户端IP -->
<%= request.getRemoteAddr() %><br/>
<!-- 获取客户端主机名 -->
<%= request.getRemoteHost() %><br/>
<!-- 获取提交表单的值 -->
<%= request.getParameter("userName") %><br/>
</body>
</html>
request对象处理数组形式的表单信息
新建三个jsp文件
在register.jsp方法中，添加：
<%@ 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>录入注册信息</title> </head> <body> <form action="doregister.jsp" method="post"> 用户名： <input type="text" name="userName"/><br/> 技能： <input type="checkbox" name="skills" value="java"/>java <input type="checkbox" name="skills" value="C"/>C <input type="checkbox" name="skills" value="python"/>python <input type="checkbox" name="skills" value="R"/>r <br/> <input type="submit" name="提交"/> <input type="reset" name="重置"/> </form> </body> </html>
在doregister.jsp中添加
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
//getParameter方法用于获取客户端浏览器通过“GET”或“POST”方法获取的表单数据，没有setParameter这个方法
String userName = request.getParameter("userName");
String skills = "";
String[] skillArr = request.getParameterValues("skills");
if(skillArr != null && skillArr.length > 0){
for(String skill : skillArr){
skills = skills + skill + " ";
}
}
//getAttribute和setAttribute用于在web组件之间共享信息
request.setAttribute("userName", userName);
request.setAttribute("skills", skills);
%>
<jsp:forward page="welcome.jsp"></jsp:forward>
在welcome.jsp中添加
<%@ 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>
用户名：<%= request.getAttribute("userName") %>
技能：<%= request.getAttribute("skills") %>
</body>
</html>
response对象
封装服务器的响应信息，用于对客户端的请求进行回应，处理http链接信息，设置http文件头，Cookie信息
<%@ 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>
<%
//设置头信息,Cache-Control用于设置缓存策略，no_cache表示数据内容不会被存储
response.setHeader("Cache-Control", "no_cache");
//设置整型的头信息, 网页每个2s刷新一次
response.setIntHeader("Refresh", 2);
//日期类型的头信息
out.println(new java.util.Date().toString() + "<br/>");
%>
</body>
</html>
用response实现页面跳转
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
//页面跳转
response.sendRedirect("http://www.baidu.com");
%>
用response访问Cookie
<%@ 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>
<%
//修改Cookie， cookie是"小甜品"，其实是一段纯文本信息，由服务器发送到浏览器
// 当浏览器再次访问该网站的时候，浏览器会把请求的网址连同该Cookie一起提交给服务器
// 服务器检查Cookie用于识别用户状态
Cookie myCookie = new Cookie("thy", "star");
myCookie.setMaxAge(3600);
response.addCookie(myCookie);
%>
</body>
</html>
exception对象
jsp执行过程中发生的异常和错误信息
创建两个jsp文件
在throw_error.jsp中添加：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ page errorPage="handle_error.jsp" %> <!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> <% int a = 1/0; %> </body> </html>
在handle.jsp中添加：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ page isErrorPage="true" %> <!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> <% out.println(exception.getMessage()); //异常描述信息 %> <br/> <% out.println(exception.toString());//exception对象的字符串描述 %> <br/> <% exception.printStackTrace();//打印异常的堆栈轨迹，向标准输出流打印，不会输出在页面上 %> </body> </html>
config对象
封装应用程序的配置信息
page对象
指向jsp程序本身
<%@ 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> <% out.println(page.toString());//page对象的字符串 page.getClass(); //返回当前的object类 page.hashCode();//对象的HashCode值 //page.equals(obj);//对象是否与指定对象相等 %> </body> </html>
session对象
保存回话信息，可以在同一用户的不同请求之间共享数据
<%@ 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> <!-- session的唯一标识符 --> <%= session.getId() %><br/> <!-- session的创建时间 --> <%= session.getCreationTime() %><br/> <!-- session的最后访问时间 --> <%= session.getLastAccessedTime() %><br/> <!-- session的失效时间 --> <%= session.getMaxInactiveInterval() %><br/> <% %> </body> </html>
session的应用
用户登陆：
新建四个jsp文件
在login.jsp中添加代码：
<%@ 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>登陆页面</title> </head> <body> <form action="do_login.jsp" method="post"> userName: <input type="text" name="userName"/><br/> password: <input type="password" name="password"/><br/> <input type="submit" value="submit"/> <input type="reset" value="reset"/> </form> </body> </html>
在do_login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
String userName = request.getParameter("userName");
String password = request.getParameter("password");
if(userName != null && password != null){
session.setAttribute("userName", userName);
response.setHeader("refresh", "2;URL=welcome.jsp");
}
%>
在welcome.jsp中添加代码
<%@ 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>欢迎页面</title>
</head>
<body>
<%if(session.getAttribute("userName") != null) {%>
欢迎<%=session.getAttribute("userName") %>
<a href="logout.jsp">注销</a>
<br/>
<%}else{ %>
请先登陆
<a href="login.jsp">登陆</a>
<%} %>
<%if(session.isNew()){ %>
<br/>
欢迎新用户！
<%}else{ %>
欢迎老用户
<%} %>
</body>
</html>
在logout.jsp中添加代码
<%@ 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">
<%
session.invalidate();//清楚session对象
response.setHeader("refresh", "2;URL=welcome.jsp");
%>
application对象
代表当前应用程序的上下文，在不同的用户之间共享信息。相对于session对象而言，application对象的生命周期更长，为用户共享某些信息提供了方便
<%@ 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> <!-- 返回当前服务 器的信息 --> <%=application.getServerInfo() %><br/> <!-- 返回当前应用名称 --> <%=application.getServletContextName() %><br/> </body> </html>
应用，记录页面的访问次数：
<%@ 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>
<%
Object obj = application.getAttribute("counter");
if(obj==null){
application.setAttribute("counter", new Integer(1));
out.println("访问1次");
}else{
int counterValue=Integer.parseInt(obj.toString());
counterValue++;
out.print(counterValue+"<br/>");
application.setAttribute("counter", counterValue);
}
%>
</body>
</html>
pageContext对象
提供对jsp所有对象及命名空间的访问
<%@ 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>
<%
//JspWriter myOut = pageContext.getOut();
//myOut.println("hello world");
pageContext.setAttribute("thy", "star", pageContext.SESSION_SCOPE);
String value = session.getAttribute("thy").toString();
out.println(value);
out.println("<br/>");
%>
</body>
</html>
极客网址：http://www.jikexueyuan.com/course/520.html
时间： 2024-10-29 14:50:02