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JDBC+Servlet+JSP整合开发之25.JSP动作元素

發布時間:2024/4/11 javascript 32 豆豆
生活随笔 收集整理的這篇文章主要介紹了 JDBC+Servlet+JSP整合开发之25.JSP动作元素 小編覺得挺不錯的,現在分享給大家,幫大家做個參考.
–jsp:useBean
–jsp:setProperty
–jsp:getProperty
–jsp:forward
–jsp:include
–jsp:param
–實例

?計算器 ------------------------------------------------------------------------ ? jsp:useBean
–格式
? <jsp:useBean id="name" class="package.Class" />
–目的
? 不需用到顯式的Java編程就能夠創建Java類的實例
–注意
? 簡單來說
–<jsp:useBean id="book1" class=“com.amaker.Book" />
? 可以認為等同于下面的scriptlet
–<% coreservlets.Book book1 = new com.amaker.Book(); %>
–但jsp:useBean擁有下面兩項額外的優勢
? 從請求參數中導出對象的值更容易
? 在頁面和servlet間共享對象更容易 User.java? TestUseBean.jsp 測試: 下面我們使用動作元素jsp:useBean來實現哈~ TestUseBean.jsp 測試: ? ? jsp:setProperty
–格式 ? <jsp:setProperty name="name“ property="property“ value="value"
/>
–目的 ? 不需用到顯式的Java編程就可以設置bean的屬性(即調用setXxx方法)
–注意 ? <jsp:setProperty name="book1“ property="title“ value=“amaker JSP" />
–等價于下面的scriptlet
? <% book1.setTitle(“Java Web Dev!"); %> ? jsp:getProperty
–格式
? <jsp:getProperty name="name" property="property" />
–目的
? 不需用到顯式的Java編程就可以訪問bean的屬性(即調用getXxx
方法)
–注意
? <jsp:getProperty name="book1" property="title" />
–等價于下面的JSP表達式
? <%= book1.getTitle() %> 下面我們通過請求參數來獲取 login.jsp TestUseBean.jsp 測試: 同樣我們也可以用param獲取參數 TestUseBean.jsp 測試: –jsp:forward
?轉發請求到指定文件
?語法
–<jsp:forward page=“URL”/>
?例如
–<jsp:forward page=“/result.jsp” /> login.jsp process.jsp 測試: 帳號michael跳轉到成功頁面。 非michael帳號跳轉到失敗頁面。 ? jsp:include
–在頁面中動態包含文件
–語法
? <jsp:include page=“URL” flush=“true”/>
–例如
? <jsp:include page=“header.jsp”flush=“true”/> TestJspInclude.jsp include.jsp 測試: ? ? jsp:param
–獲得請求參數 TestJspInclude.jsp include.jsp 測試: –實例
?計算器 Calculator.jsp ? <%@ page language="java" import="java.util.*" pageEncoding="gbk"%>????
<%@page import="com.michael.jsp.CalculatorBean"%>????
<%????
String path = request.getContextPath();????
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";????
%>????

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">????
<html>????
????<head>????
????????<base href="<%=basePath%>">????
????????<title>My JSP 'Calculator.jsp' starting page</title>????
????????<meta http-equiv="pragma" content="no-cache">????
????????<meta http-equiv="cache-control" content="no-cache">????
????????<meta http-equiv="expires" content="0">????????
????????<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">????
????????<meta http-equiv="description" content="This is my page">????
????????<!--????
????????<link rel="stylesheet" type="text/css" href="styles.css">????
????????-->????

????</head>????
????<body>????
????????<form name="f1" id="f1" action="<%=path %>/Calculator.jsp" method="post">????
????????<jsp:useBean id="cb" class="com.michael.jsp.CalculatorBean"></jsp:useBean>????
????????<jsp:setProperty property="*" name="cb"/>????
???????? <hr>????
????????????計算結果:<%????
????????????if(cb.getOperator()!=null){????
????????????????????try{????
????????????????????????????out.println(cb.getFirst()+cb.getOperator()+cb.getSecond()+"="+cb.getResult());????
????????????????????}catch(Exception e){????
????????????????????}????
????????????}else{????
????????????????????out.println("請輸入!");????
????????????}????
????????????%>????
????????????<hr>????
????????????<table border="0">????
???????????? <tr>????
????????????????????<td>第一個數:</td>????
????????????????????<td><input type="text" name="first"></td>????
????????????????</tr>????
????????????????<tr>????
????????????????<td>操作符:</td>????
????????????????<td>????
????????????????????????<select name="operator">????
????????????????????????????????<option value="+">+</option>????
????????????????????????????????<option value="-">-</option>????
????????????????????????????????<option value="*">*</option>????
????????????????????????????????<option value="/">/</option>????
????????????????????????</select>????
????????????????</td>????
????????????????</tr>????
????????????????<tr>????
????????????????????<td>第二個數:</td>????
????????????????????<td><input type="text" name="second"></td>????
????????????????</tr>????
????????????????<tr>????
????????????????????<td colspan="2" align="center"><input type="submit" value="計算"></td>????
????????????????</tr>????
????????????</table>????
????????</form>????
????</body>????
</html>
CalculatorBean.java package com.michael.jsp;????
public class CalculatorBean {????
????????private double first;????
????????private double second;????
????????private double result;????
????????private String operator;????
????????public double getFirst() {????
????????????????return first;????
????????}????
????????public void setFirst(double first) {????
????????????????this.first = first;????
????????}????
????????public double getSecond() {????
????????????????return second;????
????????}????
????????public void setSecond(double second) {????
????????????????this.second = second;????
????????}????
????????public double getResult() {????
????????????????try {????
????????????????????????if(operator!=null){????
????????????????????????????????if(operator.equals("+")){????
????????????????????????????????????????result = first + second;????
????????????????????????????????}else if(operator.equals("-")){????
????????????????????????????????????????result = first - second;????
????????????????????????????????}else if(operator.equals("*")){????
????????????????????????????????????????result = first * second;????
????????????????????????????????}else if(operator.equals("/")){????
????????????????????????????????????????result = first / second;????
????????????????????????????????}else{????
????????????????????????????????????????result = 0.0;????
????????????????????????????????}????
????????????????????????}else{????
????????????????????????????????result = 0.0;????
????????????????????????}????
????????????????} catch (Exception e) {????
????????????????????????e.printStackTrace();????
????????????????}????
????????????????return result;????
????????}????
????????public void setResult(double result) {????
????????????????this.result = result;????
????????}????
????????public String getOperator() {????
????????????????return operator;????
????????}????
????????public void setOperator(String operator) {????
????????????????this.operator = operator;????
????????}????
} 測試: 800/50 30+50 ------------------------------------------------------------------------

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