在JSP中使用EL获取Javabean的属性值

来源：互联网发布：vb中string是什么意思编辑：程序博客网时间：2024/05/21 03:20

首先，有如下的javaben文件：

package com.wrox.begjsp.ch5;import java.beans.*;import java.util.*;public class NewsFeed extends Object implements java.io.Serializable {        private String topic;        private String value;        private HashMap values;        public NewsFeed() {    }            public void setTopic(String topic) {        value = "";        values = null;        if (topic.equals("news"))  {            value = "JSP Programmer Won 10 Million in Lottery";        }        if (topic.equals("entertainment")) {            value = "Reality TV Show Ratings Falling";        }        if (topic.equals("weather")){            values = new HashMap();            values.put("Mumbai", "30 C");            values.put("Tokyo", "18 C");            values.put("Hong Kong", "28 C");                    }            }        public String getValue() {        return this.value;    }        public Map getValues() {        return this.values;    }    }

我们要在JSP页面中获取该javabean的属性：有如下jsp页面

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><jsp:useBean id="newsfeed" class="com.wrox.begjsp.ch5.NewsFeed" scope="page" /><html><head><title>EL Property Access and Nested Properties Examples</title></head><body><h1>EL Property Access and Nested Properties Examples</h1><jsp:setProperty name="newsfeed"  property="topic" value="news"/>News headline is <b>${newsfeed.value}</b>.<br/><jsp:setProperty name="newsfeed"  property="topic" value="entertainment"/>Entertainment headline is <b>${newsfeed["value"]}</b>.<br/><jsp:setProperty name="newsfeed"  property="topic" value="weather"/>The weather in Tokyo right now is ${newsfeed.values.Tokyo}.<br/>The weather in Mumbai right now is ${newsfeed["values"].Mumbai}.<br/>The weather in Hong Kong right now is ${newsfeed.values["Hong Kong"]}.<br/></body></html>

操作过程如下：

1）在JSP页面中声明所使用的JAVABEN

<jsp:useBean id="newsfeed" class="com.wrox.begjsp.ch5.NewsFeed" scope="page" />

2) 使用<jsp:setProperty>设订javaben某个属性的值

<jsp:setProperty name="newsfeed"  property="topic" value="news"/>

3）是用EL表达式获取JAVABEAN的属性值

News headline is <b>${newsfeed.value}</b>.<br/>

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