JSP和Servlet[2]
2017-01-30 21:48
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JavaBean组件
JavaBean 是使用 Java 语言开发的一个可重用的组件，在 JSP 开发中可以使用 JavaBean 减少重复代码，使整个JSP 代码的开发更简洁。1.jsp:useBean创建javaBean
<jsp:useBean id="实例化对象名称" scope="保存范围" class="类完整名称"/>Scope，一共有 page,request,session 和 application4 个属性范围，默认是 page；
2.jsp:setProperty设置javabean属性值
<jsp:setProperty property="属性名称" name="实例化对象的名称" value="属性值" param="参数名称"/>Property=”*” 自动匹配所有
3.jsp:getProperty获取javabean属性值
<jsp:getProperty property="属性名称" name="实例化对象的名称"/>4.javabean的保存范围
Javabean 的保存范围有 page,request,session.application，默认是 page；5.javabean删除
Page 范围：pageContext.removeAttribute(“javaBean Name”);request 范围：request.removeAttribute(“javaBean Name”);
session 范围：session.removeAttribute(“javaBean Name”);
application 范围：application.removeAttribute(“javaBean Name”);
EL表达式
作用：使JSP写起来更加简单1.语法结构
${expression}2.EL表达式访问4种范围属性
寻找值的顺序：page->request->session->application
JSP自定义标签
（以后整理）JSP标准标签库
1.JSTL简介
JSP 标准标签库（JSP Standard Tag Library，JSTL）是一个实现 Web应用程序中常见的通用功能的定制标记库集，这些功能包括迭代和条件判断、数据管理格式化、XML 操作以及数据库访问。使用JSTL标签库前需要导入两个包，分别是jstl.jar和standard.jar。
2.JSTL核心标签库
c:out 内容输出标签；<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
pageContext.setAttribute("people","张三");
%>
<h2><c:out value="${people}"></c:out></h2>
<h2><c:out value="${people2}" default="某人"></c:out></h2>
</body>
</html>c:set 用来设置 4 中属性范围值的标签；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:set var="people" value="张三" scope="request"></c:set>
<h2><c:out value="${people}"></c:out></h2>
<jsp:useBean id="people2" class="cn.cslg.model.People" scope="page"></jsp:useBean>
<c:set property="id" target="${people2 }" value="007"></c:set>
<c:set property="name" target="${people2 }" value="王二小"></c:set>
<c:set property="age" target="${people2 }" value="16"></c:set>
<h2>编号：${people2.id }</h2>
<h2>姓名：${people2.name }</h2>
<h2>年龄：${people2.age }</h2>
</body>
</html>c:remove 用来删除指定范围中的属性；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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>
<c:set var="people" value="张三" scope="request"></c:set>
<h2><c:out value="${people}" default="没人啊"></c:out></h2>
<c:remove var="people" scope="request"/>
<h2><c:out value="${people}" default="没人啊"></c:out></h2>
</body>
</html>c:catch 用来处理程序中产生的异常；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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>
<c:catch var="errMsg">
<%
int a=1/0;
%>
</c:catch>
<h2>异常信息：${errMsg }</h2>
</body>
</html>c:if 用来条件判断；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<jsp:useBean id="people" class="cn.cslg.model.People" scope="page"></jsp:useBean>
<c:set property="id" target="${people }" value="007"></c:set>
<c:set property="name" target="${people }" value="王二小"></c:set>
<c:set property="age" target="${people }" value="16"></c:set>
<c:if test="${people.name=='王二小' }" var="r" scope="page">
<h2>是王二小</h2>
</c:if>
<c:if test="${people.age<18 }">
<h2>是未成年</h2>
</c:if>
</body>
</html>c:choose、c:when、c:otherwise 用来多条件判断；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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>
<jsp:useBean id="people" class="cn.cslg.model.People" scope="page"></jsp:useBean>
<c:set property="id" target="${people }" value="007"></c:set>
<c:set property="name" target="${people }" value="王二小"></c:set>
<c:set property="age" target="${people }" value="19"></c:set>
<c:choose>
<c:when test="${people.age<18 }">
<h2>小于18</h2>
</c:when>
<c:when test="${people.age==18 }">
<h2>等于18</h2>
</c:when>
<c:otherwise>
<h2>大于18</h2>
</c:otherwise>
</c:choose>
</body>
</html>c:forEach 用来遍历数组或者集合；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="cn.cslg.model.*"%>
<%@ page import="java.util.*"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
String dogs[]={"小黑","小黄","小白","小小"};
pageContext.setAttribute("dogs",dogs);
%>
<c:forEach var="dog" items="${dogs }">
${dog }
</c:forEach>
<hr/>
<c:forEach var="dog" items="${dogs }" step="2">
${dog }
</c:forEach>
<hr/>
<c:forEach var="dog" items="${dogs }" begin="1" end="2">
${dog }
</c:forEach>
<hr/>
<%
List<People> pList=new ArrayList<People>();
pList.add(new People(1,"张三",10));
pList.add(new People(2,"李四",20));
pList.add(new People(3,"王五",30));
pageContext.setAttribute("pList",pList);
%>
<table>
<tr>
<th>编号</th>
<th>姓名</th>
<th>年龄</th>
</tr>
<c:forEach var="p" items="${pList }">
<tr>
<td>${p.id }</td>
<td>${p.name }</td>
<td>${p.age }</td>
</tr>
</c:forEach>
</table>
</body>
</html>c:fortokens 分隔输出；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
String str1="www.google.com";
String str2="张三，李四，王五";
pageContext.setAttribute("str1",str1);
pageContext.setAttribute("str2",str2);
%>
<c:forTokens items="${str1 }" delims="." var="s1">
${s1 }
</c:forTokens>
<hr/>
<c:forTokens items="${str2 }" delims="，" var="s2">
${s2 }
</c:forTokens>
</body>
</html>c:import 导入页面；
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <c:import url="c_forEach.jsp"></c:import> <c:import url="c_if.jsp"></c:import> </body> </html>
c:url 生成一个 url 地址；
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:url value="http://www.google.com" var="url">
<c:param name="name" value="admin"></c:param>
<c:param name="age" value="3"></c:param>
</c:url>
<a href="${url }">CBA</a>
</body>
</html>c:redirect 客户端跳转
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!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> <c:redirect url="target.jsp"> <c:param name="name" value="abc"></c:param> <c:param name="age" value="26"></c:param> </c:redirect> </body> </html>
3.JSTL国际化标签库
fmt:setLocale 设定用户所在的区域；fmt:formatDate 对日期进行格式化；
fmt:requestEncoding 设置所有的请求编码；
fmt:bundle fmt:message 读取国际化资源；
fmt:formatNumber 格式化数字；
fmt:formatDate 格式化日期；
fmt:timeZone 设置临时时区；
4.JSTL SQL标签库
Sql:setDataDource 设置 JDBC 连接;sql:query 数据库查询操作；
Sql:update 数据库添加，修改，删除操作；
Sql:transaction 数据库事务；
5.JSTL XML标签库
x:parse 解析 xml；x:out 输出 xml 文件的内容；
x:set 把 xml 读取的内容保存到指定的属性范围；
x:if 判断指定路径的内容是否符合判断的条件；
x:choose x:when x:otherwise 多条件判断；
x:forEach 遍历
6.JSTL函数标签库
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn"%>
<!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("info","www.google.com");
%>
<h2>查找google位置:${fn:indexOf(info,"google")}</h2>
<h2>判断google是否存在:${fn:contains(info,"google")}</h2>
<h2>截取:${fn:substring(info,0,5)}</h2>
<h2>拆分:${fn:split(info,".")[1]}</h2>
</body>
</html>
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