JSP编程-步步为营

时间：2022-01-05 07:12:59

【第一个JSP举例】

header.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">

<title>Insert title here</title>

</head>

<body>

<% out.println("welcome调用这个JSP页面"); %>

　　footer.jsp

<br>

</body>

</html>

　　jsp代码

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<%@ include file="/header.jsp" %><%--包含页头 --%>

<%!

int i=0;

private int count(){

	i++;

	return i;

}

%>

<p>调用count输出<%=count() %></p>

<p>调用count输出<%=count() %></p>

<br>

<%@ include file="/footer.jsp" %><%--包含页底 --%>

　　JSP编程-步步为营

【概念总结】

language定义使用的脚本语言
contentType定义jsp字符编码和页面响应的MIME类型
pageEncoding jsp页面的字符编码

scriptlet标签

<%! %>可定义全局变量、全局方法、全局类
<% %>可定义局部变量
<%= %>输出

JSP注释
<!-- -->HTML客户端可见
<%-- --%>客户端不可见
//单行注释
/* 多行注释 */

静态包含
<%@ include file="header.html" %>
<%@ include file="footer.jsp" %>
动态包含
<jsp:include page="header.html" />
<jsp:include page="footer.jsp" />

【jsp九大内置对象】
pageContext request response session application config

out page exception

【四大作用域】
Page范围 只在一个页面中保存数据 抽象类
Request范围 只在一个请求中保存数据 接口
Session范围 在一个会话范围中保存数据，仅供单个用户使用

接口
Application范围 在整个服务器上保存数据，所有用户共享

【Page范围】

<%@ 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>

<%

pageContext.setAttribute("name","名字");

pageContext.setAttribute("age",24);

%>

<%

String str1=(String)pageContext.getAttribute("name");

int n=(Integer)pageContext.getAttribute("age");

%>

<p>姓名：<%=str1 %></p>

<p>年龄：<%=n %></p>

</body>

</html>

　　【Request范围】

<%@ 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>

<%

request.setAttribute("name","马云");

request.setAttribute("age",23);

request.setAttribute("sex","男");

%>

<jsp:forward page="f_target.jsp"></jsp:forward>

</body>

</html>

　　

<%@ 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 str=(String)request.getAttribute("name");

int age=(Integer)request.getAttribute("age");

String sex=(String)request.getAttribute("sex");

%>

<p>姓名：<%=str %></p>

<p>年龄：<%=age %></p>

<p>性别: <%=sex %></p>

</body>

</html>

　　【Session范围】

session保存在服务器中，只要页面不关闭，就可以随时取得

<%@ 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>Session</title>

</head>

<body>

<h3>设置Session</h3>

<%

session.setAttribute("bookName","JAVA编程");

session.setAttribute("price",25.5);

%>

</body>

</html>

　　

<%@ 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>get Session</title>

</head>

<body>

<%

String bookName=(String)session.getAttribute("bookName");

double price=(Double)session.getAttribute("price");

%>

<p>图书名称：<%=bookName %></p>

<p>图书价格：<%=price %></p>

</body>

</html>

　　【Application范围】范围更大，浏览器关闭或者换用其他浏览器，也可以访问数据

<%@ 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>Application</title>

</head>

<body>

<%

application.setAttribute("bookName","数据库");

application.setAttribute("price",45.85);

%>

</body>

</html>

　　

<%@ 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>Application</title>

</head>

<body>

<%

String bookName=(String)application.getAttribute("bookName");

double price=(Double)application.getAttribute("price");

%>

<p>图书名称：<%=bookName %></p>

<p>图书价格：<%=price %></p>

</body>

</html>

　　知识点：

【获取Request的头信息】jsp引入 枚举

输出 name value

<%@ page import="java.util.*" %>

<%

Enumeration e=request.getHeaderNames();

while(e.hasMoreElements()){

String name=(String)e.nextElement();

String value=request.getHeader(name);

%>

<p><%=name %>    <%=value %></p>

<%

}

%>

　　

【Response】示例：每隔一秒刷新时间

<%

response.setIntHeader("Refresh",1);

Date date=new Date();

%>

<h3>时间</h3>

<%=date.toLocaleString() %>

　　网页重定向

<h3>网页重定向-客户端跳转</h3>

<%--response.sendRedirect("page4.jsp");--%>

　　

<h3>用户登录post</h3>

<form action="login.jsp" method="post">

用户：<input type="text" name="userName" /><br><br>

密码：<input type="password" name="password" /><br><br>

记住我<input type="checkbox" name="remember" value="remember" /><br><br>

<input type="submit" value="提交" />

<input type="reset" value="重置" />

</form>

　　login.jsp的代码

<%

String name=request.getParameter("userName");

String pass=request.getParameter("password");

String rem=request.getParameter("remember");

%>

<%=name %>

<%=pass %>

<%=rem %>

　　

post get比较
post放在数据包里-get放在Url后面
get数据量小、不安全

【Cookie示例】用户登录记住用户名和密码

<%@ page language="java" contentType="text/html; 

charset=utf-8"

    pageEncoding="utf-8"%>

<%@ page import="java.util.*" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 

Transitional//EN" 

"http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<script>

function resetValue(){

	document.getElementById("userName").value="";

	document.getElementById("password").value="";

}

</script>

<meta http-equiv="Content-Type" content="text/html; 

charset=utf-8">

<title>Test response</title>

</head>

<body>

<%

String userName=null;

String password=null;

Cookie[] cos=request.getCookies();

Cookie c=null;

for(int i=0;i<cos.length;i++){

    c=cos[i];

    if(c.getName().equals("nameAndPass")){

        //out.println("保存的用户名和密码"+c.getValue

());

        userName=c.getValue().split("-")[0];

        password=c.getValue().split("-")[1];

    }

}

if(userName==null){userName="";}

if(password==null){password="";}

%>

<h3>用户登录post</h3>

<form action="login.jsp" method="post">

用户：<input type="text" name="userName" id="userName" 

value="<%=userName %>"/><br><br>

密码：<input type="password" name="password" 

id="password" value="<%=password %>"/><br><br>

记住我<input type="checkbox" name="remember" 

value="remember" /><br><br>

<input type="submit" value="提交" />

<input type="button" value="重置" onclick="resetValue()" 

/>

</form>

</body>

</html>

　　

<%@ page language="java" contentType="text/html; 

charset=utf-8"

	pageEncoding="utf-8"%>

    <%@ page import="javax.servlet.http.*" %>

<!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>login.jsp</title>

</head>

<body>

<%

String name=request.getParameter("userName");

String pass=request.getParameter("password");

String rem=request.getParameter("remember");

if("remember".equals(rem)){

	Cookie c=new Cookie("nameAndPass",name

+"-"+pass);

	c.setMaxAge(24*60*60*7);//记录一个星期

	response.addCookie(c);//保存Cookie

}

response.sendRedirect("page5_response.jsp");

%>

</body>

</html>

　　【out对象】

<%@ 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>Test out</title>

</head>

<body>

<%

int total=out.getBufferSize();//总缓存大小

int noUse=out.getRemaining();//未使用缓存大小

int u=total-noUse;

%>

<p>总缓存大小：<%=total %></p>

<p>未使用缓存大小：<%=noUse %></p>

<p>已使用缓存大小：<%=u %></p>

</body>

</html>

　　【config对象】

config.getInitParameter();//获得xml里的初始化参数param

　　【exception异常处理】

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

    <%@ page errorPage="ex2.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>Exception</title>

</head>

<body>

<%

int a=1;

int b=0;

out.println(a/b);

%>

</body>

</html>

　　

<%@ 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>isErrorPage</title>

</head>

<body>

<%

if(exception!=null){

	String str=exception.getMessage();

	out.println("错误提示信息:<br>");

	out.println(str);

}

%>

</body>

</html>

　　此处需要在浏览器中运行，不在tomcat里运行

JSP编程-步步为营

【pageContext对象】页面上下文

<%

pageContext.setAttribute("name0","pageInfo");

request.setAttribute("name1","requestInfo");

session.setAttribute("name2","sessionInfo");

application.setAttribute("name3","applicationInfo");

out.println("->"+pageContext.getAttribute("name0")+"<br>");

out.println("->"+pageContext.getRequest().getAttribute("name1")+"<br>");

out.println("->"+pageContext.getSession().getAttribute("name2")+"<br>");

out.println("->"+session.getServletContext().getAttribute("name3")+"<br>");

%>

　　

相关文章