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  • JavaBean的应用

    1. 获取JavaBean属性信息

    例1.1 在JSP页面中显示JavaBean属性信息。

    (1)创建名称为Produce的类,该类是封装商品对象的JavaBean,在Produce类中创建商品属性,并提供相应的getXXX()方法。关键代码如下:

    package com.cn.gao;
    
    public class Produce {
        //商品名称
        private String name="电吉他";
        private double price = 1880.5;
        private int count = 100;
        private String factoryAdd = "吉林省长春市XXX琴行";
        
        public String getName() {
            return name;
        }
        
        public double getPrice() {
            return price;
        }
        
        public int getCount() {
            return count;
        }
        
        public String getFactoryAdd() {
            return factoryAdd;
        }
        
        
    }

    (2)在JSP页面中获取商品JavaBean中的属性信息,该操作通过JSP动作标签进行获取。关键代码如下:

    produce.jsp

    <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
    <%
    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 'produce.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>
        <jsp:useBean id="produce" class="com.cn.gao.Produce"></jsp:useBean>
        <div>
            <ul>
                <li>
                    商品名称:<jsp:getProperty property="name" name="produce"/>
                </li>
                <li>
                    价格:<jsp:getProperty property="price" name="produce"/>
                </li>
                <li>
                    数量:<jsp:getProperty property="count" name="produce"/>
                </li>
                <li>
                    厂址:<jsp:getProperty property="factoryAdd" name="produce"/>
                </li>
            </ul>
        </div>
      </body>
    </html>

    本实例中主要通过<jsp:useBean>标签实例化商品的JavaBean对象,<jsp:getProperty>标签获取JavaBean中的属性信息。实例运行结果如下图:

    注:<jsp:useBean>标签与<jsp:getProperty>标签之所以能够操作Java类,是因为我们所编写的Java类遵循了JavaBean规范。所以在编写JavaBean时要遵循制定的JavaBean规范。

     2. 对JavaBean属性赋值

    例2.1 创建商品对象的JavaBean,在该类中提供属性及与属性相对应的get和set方法,在JSP页面中对JavaBean属性赋值并获取输出。

    (1)创建名称为Produce的类,该类是封装商品信息的JavaBean,在该类中创建商品属性及与属性相应的get和set方法。关键代码如下:

    package com.cn.gao;
    
    public class Produce {
        //商品名称
        private String name;
        private double price;
        private int count;
        private String factoryAdd;
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public double getPrice() {
            return price;
        }
        public void setPrice(double price) {
            this.price = price;
        }
        public int getCount() {
            return count;
        }
        public void setCount(int count) {
            this.count = count;
        }
        public String getFactoryAdd() {
            return factoryAdd;
        }
        public void setFactoryAdd(String factoryAdd) {
            this.factoryAdd = factoryAdd;
        }
        
        
    }

    (2)创建名称为produce.jsp页面,在该页面中实例化Produce对象,然后对其属性进行赋值并输出。关键代码如下:

    <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
    <%
    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 'produce.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>
        <jsp:useBean id="produce" class="com.cn.gao.Produce"></jsp:useBean>
        <jsp:setProperty property="name" name="produce" value="洗衣机"/>
        <jsp:setProperty property="price" name="produce" value="888.88"/>
        <jsp:setProperty property="count" name="produce" value="88"/>
        <jsp:setProperty property="factoryAdd" name="produce" value="广东省XXX公司"/>
        <div>
            <ul>
                <li>
                    商品名称:<jsp:getProperty property="name" name="produce"/>
                </li>
                <li>
                    价格:<jsp:getProperty property="price" name="produce"/>
                </li>
                <li>
                    数量:<jsp:getProperty property="count" name="produce"/>
                </li>
                <li>
                    厂址:<jsp:getProperty property="factoryAdd" name="produce"/>
                </li>
            </ul>
        </div>
      </body>
    </html>

    页面主要是通过<jsp:useBean>标签实例化商品的JavaBean对象,<jsp:setProperty>标签对Produce对象中的属性赋值,然后再通过<jsp:getProperty>标签输出已赋值的Produce对象中的属性信息。实例运行结果如下图所示:

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  • 原文地址:https://www.cnblogs.com/gaopeng527/p/4419134.html
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