JEE_JavaBean

JavaBean：通过Java代码封装的Java类，以实现JSP页面中(HTML/CSS代码，JSP代码)和Java代码的分离和代码的重用。JavaBean封装后可在JSP页面中调用.

JavaBean严格规范:

1.公共的无参的构造方法(无参:<jsp:useBean>),

2.类的声明是非final型的(数据可以修改),

3.实现可序列化接口,

1.JavaBean中的属性可设置为private防止外部访问,但需对外提供public的访问方法(get/set方法:<jsp:getProperty>,<jsp:setProperty>).

示例:

GreetingBean.java

package com.lyq.Bean;
/**
 * JavaBean对象
 * @author Li YongQiang
 */
public class GreetingBean {
    // 用户名
    private String userName;
    // 问候指定用户
    public String getUserName() {
        return userName + "，你好！" ;
    }
    // 设置用户
    public void setUserName(String userName) {
        this.userName = userName;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@page import="com.lyq.Bean.GreetingBean"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>主页</title>
</head>
<body>
    <%
        GreetingBean bean = new GreetingBean();
        bean.setUserName("明日科技");
        out.print(bean.getUserName());
    %>
</body>
</html>

例:通过非可视化的JavaBean,封装邮箱地址对象,通过JSP页面调用此对象,来验证邮箱地址是否合法.

Emai.java

package com.lyq.bean;

import java.io.Serializable;
/**
 * 邮件对象JavaBean
 * @author Li YongQiang
 */
public class Email implements Serializable {
    //  serialVersionUID 值
    private static final long serialVersionUID = 1L;//序列号版本号
    // Email地址
    private String mailAdd;
    // 是否是一个标准的Email地址
    private boolean eamil;
    /**
     * 默认无参的构造方法
     */
    public Email() {
    }
    /**
     * 构造方法
     * @param mailAdd Email地址
     */
    public Email(String mailAdd) {
        this.mailAdd = mailAdd;
    }
    /**
     * 是否是一个标准的Email地址
     * @return 布尔值
     */
    public boolean isEamil() {
        // 正则表达式，定义邮箱格式
        String regex = "\\w+([-+.']\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*"; 
        // matches()方法可判断字符串是否与正则表达式匹配
        if (mailAdd.matches(regex)) { 
            // eamil为真
            eamil = true;
        }
        // 返回eamil
        return eamil;
    }
    public String getMailAdd() {
        return mailAdd;
    }
    public void setMailAdd(String mailAdd) {
        this.mailAdd = mailAdd;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
    <form action="result.jsp" method="post">
        <table align="center" width="300" border="1" height="150">
            <tr>
                <td colspan="2" align="center">
                    <b>邮箱认证系统</b>
                </td>
            </tr>
            <tr>
                <td align="right">邮箱地址：</td>
                <td><input type="text" name="mailAdd"/></td>
            </tr>
            <tr>
                <td colspan="2" align="center">
                    <input type="submit" />
                </td>
            </tr>
        </table>
    </form>
</body>
</html>

result.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<%@page import="com.lyq.bean.Email"%><html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
    <div align="center">
        <%
            // 获取邮箱地址
            String mailAdd = request.getParameter("mailAdd");
            // 实例化Email,并对mailAdd赋值
            Email email = new Email(mailAdd);
            // 判断是否是标准的邮箱地址
            if(email.isEamil()){
                out.print(mailAdd + " <br>是一个标准的邮箱地址！<br>");
            }else{
                out.print(mailAdd + " <br>不是一个标准的邮箱地址！<br>");
            }
        %>
        <a href="index.jsp">返回</a>
    </div>
</body>
</html>

JavaBean应用:

在JSP页面中应用JavaBean非常简单,主要通过JSP动作标签<jsp:useBean>,<jsp:getProperty>,<jsp:setProperty>来实现对JavaBean对象的操作,但前提是所编写的JavaBean要符合JavaBean规范,只有严格遵循JavaBean规范,在JSP页面中才能方便地调用和操作JavaBean对象.(内部的操作也是通过规范化的JavaBean进行处理的)

例:对JavaBean属性赋值,获取JavaBean属性信息

Produce.java

package com.lyq.bean;
/**
 * 商品对象
 * @author Li YongQiang
 */
public class Produce {
    // 商品名称
    private String name ;
    // 商品价格
    private double price ;
    // 数量
    private int count ;
    // 出厂地址
    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;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
    <jsp:useBean id="produce" class="com.lyq.bean.Produce"></jsp:useBean>  //实例化JavaBean对象
    <jsp:setProperty property="name" name="produce" value="洗衣机"/>
    <jsp:setProperty property="price" name="produce" value="8888.88"/>
    <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>

例:在JSP页面中应用JavaBean

reg.jsp页面<jsp:userBean>标签实例化了JavaBean,然后通过<jsp:setProperty name="person" property="*"/>对Person类中的所有属性进行赋值.

使用这种方法的前提是表单中name属性的名称要和JavaBean中所定义的属性名称一致.

如若表单中name属性的名称和JavaBean中的属性名称不一致,则必须通过<jsp:setProperty>标签中的param属性来指定表单中的属性.

如表单中name为"username",可以使用<jsp:setProperty name="person" property="name" param="username"/>对齐进行赋值.

Person.java

package com.lyq.bean;
/**
 * 用户信息
 * @author Li YongQiang
 */
public class Person {
    // 姓名
    private String name;
    // 年龄
    private int age;
    // 性别
    private String sex;
    // 住址
    private String add;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String getAdd() {
        return add;
    }
    public void setAdd(String add) {
        this.add = add;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
    <form action="reg.jsp" method="post">
        <table align="center" width="400" height="200" border="1">
            <tr>
                <td align="center" colspan="2" height="40">
                    <b>添加用户信息</b>
                </td>
            </tr>
            <tr>
                <td align="right">姓　名：</td>
                <td>
                    <input type="text" name="name">
                </td>
            </tr>
            <tr>
                <td align="right">年　龄：</td>
                <td>
                    <input type="text" name="age">
                </td>
            </tr>
            <tr>
                <td align="right">性　别：</td>
                <td>
                    <input type="text" name="sex">
                </td>
            </tr>
            <tr>
                <td align="right">住　址：</td>
                <td>
                    <input type="text" name="add">
                </td>
            </tr>
            <tr>
                <td align="center" colspan="2">
                    <input type="submit" value="添　加">
                </td>
            </tr>
        </table>
    </form>
</body>
</html>

reg.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>    //Java代码
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
    <%request.setCharacterEncoding("GB18030");%>
    <jsp:useBean id="person" class="com.lyq.bean.Person" scope="page">
        <jsp:setProperty name="person" property="*"/>
    </jsp:useBean>
    <table align="center" width="400">
        <tr>
            <td align="right">姓　名：</td>
            <td>
                <jsp:getProperty property="name" name="person"/>
            </td>
        </tr>
        <tr>
            <td align="right">年　龄：</td>
            <td>
                <jsp:getProperty property="age" name="person"/>
            </td>
        </tr>
        <tr>
            <td align="right">性　别：</td>
            <td>
                <jsp:getProperty property="sex" name="person"/>
            </td>
        </tr>
        <tr>
            <td align="right">住　址：</td>
            <td>
                <jsp:getProperty property="add" name="person"/>
            </td>
        </tr>
    </table>
</body>
</html>

JavaBean在JSP中的应用:

随着学习了JSTL标签库及EL表达式或一些MVC框架后,就可以完全通过标签来取代所有JSP页面中的Java代码了,真正实现代码分离.

上例的reg.jsp页面中仍含有处理中文编码的Java代码,此处给出一例,实现JavaBean解决中文编码问题:

News.java

package com.lyq.bean;
/**
 * 新闻对象
 * @author Li YongQiang
 */
public class News {
    // 标题
    private String title;
    // 内容
    private String content;
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
}

CharactorEncoding.java

package com.lyq.bean;

import java.io.UnsupportedEncodingException;
/**
 * 字符编码处理JavaBean
 * @author Li YongQiang
 */
public class CharactorEncoding {
    /**
     * 构造方法
     */
    public CharactorEncoding(){
    }
    /**
     * 对字符进行转码处理
     * @param str 要转码的字符串
     * @return 编码后的字符串
     */
    public String toString(String str){
        // 转换字符
        String text = "";
        // 判断要转码的字符串是否有效
        if(str != null && !"".equals(str)){
            try {
                // 将字符串进行编码处理
                text = new String(str.getBytes("iso8859-1"),"GB18030");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        // 返回后的字符串
        return text;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>XX新闻发布系统</title>
</head>
<body>
    <form action="release.jsp" method="post">
        <table align="center" width="450" height="260" border="1">
            <tr>
                <td align="center" colspan="2" height="40" >
                    <b>新闻发布</b>
                </td>
            </tr>
            <tr>
                <td align="right">标　题：</td>
                <td>
                    <input type="text" name="title" size="30">
                </td>
            </tr>
            <tr>
                <td align="right">内　容：</td>
                <td>
                    <textarea name="content" rows="8" cols="40"></textarea>
                </td>
            </tr>
            <tr>
                <td align="center" colspan="2">
                    <input type="submit" value="发　布">
                </td>
            </tr>
        </table>
    </form>
</body>
</html>

release.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>发布结果</title>
<style type="text/css">
    #container{
        width: 450px;
        border: solid 1px;
        padding: 20px;
    }
    #title{
        font-size: 16px;
        font-weight: bold;
        color: #3399FF;
    }
    #content{
        font-size: 12px;
        text-align: left;
    }
</style>
</head>
<body>
    <jsp:useBean id="news" class="com.lyq.bean.News"></jsp:useBean>
    <jsp:useBean id="encoding" class="com.lyq.bean.CharactorEncoding"></jsp:useBean>
    <jsp:setProperty property="*" name="news"/>
    <div align="center">
        <div id="container">
            <div id="title">
                <%= encoding.toString(news.getTitle())%>
            </div>
            <hr>
            <div id="content">
                <%= encoding.toString(news.getContent())%>
            </div>
        </div>
    </div>
</body>
</html>

例:获取当前时间的JavaBean

DateBean.java

package com.lyq.bean;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
/**
 * 获取当前时间的JavaBean
 * @author Li YongQiang
 * 
 */
public class DateBean {
    // 日期及时间
    private String dateTime;
    // 星期
    private String week;
    // Calendar对象
    private Calendar calendar = Calendar.getInstance();
    /**
     * 获取当前日期及时间
     * @return 日期及时间的字符串
     */
    public String getDateTime() {
        // 获取当前时间
        Date currDate = Calendar.getInstance().getTime();
        // 实例化SimpleDateFormat
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日　HH点mm分ss秒");
        // 格式化日期时间
        dateTime = sdf.format(currDate);
        // 返回日期及时间的字符串
        return dateTime;
    }
    /**
     * 获取星期几
     * @return 返回星期字符串
     */
    public String getWeek() {
        // 定义数组
        String[] weeks = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };
        // 获取一星期的某天
        int index = calendar.get(Calendar.DAY_OF_WEEK);
        // 获取星期几
        week = weeks[index - 1];
        // 返回星期字符串
        return week;
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>电子时钟</title>
<style type="text/css">
    #clock{
        width:420px;
        height:80px;
        background:#E0E0E0;
        font-size: 25px;
        font-weight: bold;
        border: solid 5px orange;
        padding: 20px;
    }
    #week{
        padding-top:15px;
        color: #0080FF;
    }
</style>
<meta http-equiv="Refresh" content="1">
</head>
<body>
    <jsp:useBean id="date" class="com.lyq.bean.DateBean" scope="application"></jsp:useBean>
    <div align="center">
        <div id="clock">
            <div id="time">
                <jsp:getProperty property="dateTime" name="date"/>
            </div>
            <div id="week">
                <jsp:getProperty property="week" name="date"/>
            </div>
        </div>
    </div>
</body>
</html>

例:数组转换成字符串

Paper.java

package com.lyq.bean;

import java.io.Serializable;
/**
 * 调查问卷
 * @author Li YongQiang
 */
public class Paper implements Serializable {
    private static final long serialVersionUID = 1L;
    // 编程语言
    private String[] languages;
    // 掌握技术
    private String[] technics;
    // 部分
    private String[] parts;
    
    public Paper(){
    }
    public String[] getLanguages() {
        return languages;
    }
    public void setLanguages(String[] languages) {
        this.languages = languages;
    }
    public String[] getTechnics() {
        return technics;
    }
    public void setTechnics(String[] technics) {
        this.technics = technics;
    }
    public String[] getParts() {
        return parts;
    }
    public void setParts(String[] parts) {
        this.parts = parts;
    }
}

Convert.java

package com.lyq.bean;
/**
 * 转换数组的JavaBean
 * @author Li YongQiang
 */
public class Convert {
    /**
     * 将数组转换成为字符串
     * @param arr 数组
     * @return 字符串
     */
    public String arr2Str(String[] arr){
        // 实例化StringBuffer
        StringBuffer sb = new StringBuffer();
        // 判断arr是否为有效数组
        if(arr != null && arr.length > 0){
            // 遍历数组
            for (String s : arr) {
                // 将字符串追加到StringBuffer中
                sb.append(s);
                // 将字符串追加到StringBuffer中
                sb.append(",");
            }
            // 判断字符串长度是否有效
            if(sb.length() > 0){
                // 截取字符
                sb = sb.deleteCharAt(sb.length() - 1);
            }
        }
        // 返回字符串
        return sb.toString();
    }
}

index.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>调查问卷</title>
</head>

<body>
    <form action="reg.jsp" method="post">
        <div>
            <h1>调查问卷</h1>
            <hr/>
            <ul>
                <li>你经常用哪些编程语言开发程序：</li>
                <li>
                    <input type="checkbox" name="languages" value="JAVA">JAVA
                    <input type="checkbox" name="languages" value="PHP">PHP
                    <input type="checkbox" name="languages" value=".NET">.NET
                    <input type="checkbox" name="languages" value="VC++">VC++
                </li>
            </ul>
            <ul>
                <li>你目前所掌握的技术：</li>
                <li>
                    <input type="checkbox" name="technics" value="HTML">HTML
                    <input type="checkbox" name="technics" value="JAVA BEAN">JAVA BEAN
                    <input type="checkbox" name="technics" value="JSP">JSP
                    <input type="checkbox" name="technics" value="SERVLET">SERVLET
                </li>
            </ul>
            <ul>
                <li>在学习中哪一部分感觉有困难：</li>
                <li>
                    <input type="checkbox" name="parts" value="JSP">JSP
                    <input type="checkbox" name="parts" value="STRUTS">STRUTS
                </li>
            </ul>
            <input type="submit" value="提　交">
        </div>
    </form>
</body>
</html>

reg.jsp

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!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=GB18030">
<title>调查结果</title>
</head>

<body>
    <jsp:useBean id="paper" class="com.lyq.bean.Paper"></jsp:useBean>
    <jsp:useBean id="convert" class="com.lyq.bean.Convert"></jsp:useBean>
    <jsp:setProperty property="*" name="paper"/>
    <div>
        <h1>调查结果</h1>
        <hr/>
        <ul>
            <li>
                你经常用使用的编程语言：<%= convert.arr2Str(paper.getLanguages()) %> 。
            </li>
            <li>
                你目前所掌握的技术：<%= convert.arr2Str(paper.getTechnics()) %> 。
            </li>
            <li>
                在学习中感觉有困难的部分：<%= convert.arr2Str(paper.getParts()) %> 。
            </li>
        </ul>
    </div>
</body>
</html>

posted @ 2012-08-14 18:26 汤姆是一只猫阅读(456) 评论(0) 编辑收藏举报

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