javaweb学习--javabean

2018-09-18 06:35:39来源：博客园阅读 ()

阅读电子书《Java Web从入门到精通》密码：461c，学习JavaWeb基础知识

JavaBean类似于.net的实体类，但是规则上稍复杂一些，能实现的功能也多一些

一、介绍

1、规则

 1 package com.lyq.bean;
 2 
 3 /**
 4  * 新闻（乱码处理）
 5  * @author Administrator
 6  *
 7  */
 8 public class News {
 9     private String title;
10     private String content;
11 
12     public String getTitle() {
13         return this.title;
14     }
15 
16     public void setTitle(String title) {
17         this.title = title;
18     }
19 
20     public String getContent() {
21         return this.content;
22     }
23 
24     public void setContent(String content) {
25         this.content = content;
26     }
27 }

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可无构造函数，每个属性都是私有，使用setXX赋值getXX取值。若有默认值，可自行添加构造函数处理

2、使用

在jsp页面中使用以下代码实例化使用

1 <jsp:useBean id="自定义id" class="javabean类的全路径"></jsp:useBean>

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以下代码赋值

1 <jsp:setProperty property="属性名" name="自定义的javabean的Id" />

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以下代码取值

1 <jsp:getProperty property="属性值" name="自定义的javabean的id" />

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1 自定义javabea的id.getXX()

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完成代码为

1 <form action="news_release.jsp" method="post">
2         <b>新闻发布</b><br />
3     标题：<input name="title" id="title" /><br />
4     内容：<textarea name="content" id="content" rows="8" cols="40"></textarea><br />
5     <input type="submit" value="发布" />
6 </form>

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1 <jsp:useBean id="news" class="com.lyq.bean.News"></jsp:useBean>
2 <jsp:useBean id="encoding" class="com.lyq.bean.CharactorEncoding"></jsp:useBean>
3 <jsp:setProperty property="*" name="news" />
4 <div><%= encoding.toString(news.getTitle()) %></div><br />
5 <div><%= encoding.toString(news.getContent()) %></div><br />

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 1 package com.lyq.bean;
 2 
 3 import java.io.UnsupportedEncodingException;
 4 
 5 /**
 6  * 乱码处理类
 7  * 
 8  * @author Administrator
 9  *
10  */
11 public class CharactorEncoding {
12     /**
13      * 构造方法
14      */
15     public CharactorEncoding() {
16 
17     }
18 
19     /**
20      * 对字符串进行转码处理
21      * 
22      * @param str
23      *            要转码的字符串
24      * @return 编码后的字符串
25      */
26     public String toString(String str) {
27         String text = "";
28         if (str == null || "".equals(str))
29             return text;
30         try{
31             text = new String(str.getBytes("ISO-8859-1"), "UTF-8");
32         }catch(UnsupportedEncodingException e){
33             e.printStackTrace();
34         }
35         
36         return text;
37     }
38 }

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二、使用案例

1、邮箱验证

jsp页面

1 <form action="email_result.jsp" method="post">
2 邮箱格式验证<br />
3 邮箱地址：<input type="text" name="mailAdd" id="mailAdd" /><br />
4 <input type="submit" value="验证" />
5 </form>

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jsp验证结果页面

 1 <body>
 2     <div align="center">
 3         <%
 4             String mailAdd = request.getParameter("mailAdd");
 5             Email email = new Email(mailAdd);
 6             if (email.isEmail()) {
 7                 out.print(mailAdd + " <br />是一个标准的邮箱地址！<br />");
 8             } else {
 9                 out.print(mailAdd + " <br />不是一个标准的邮箱地址！<br />");
10             }
11         %>
12         <a href="email.jsp">返回</a>
13     </div>
14 </body>

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javabean代码

 1 package com.lyq.bean;
 2 
 3 import java.io.Serializable;
 4 
 5 /**
 6  * 邮箱类
 7  * 
 8  * @author Administrator
 9  *
10  */
11 public class Email implements Serializable {
12     /**
13      * serialVersionUID值
14      */
15     private static final long serialVersionUID = 1L;
16     /**
17      * Email地址
18      */
19     private String mailAdd;
20     /**
21      * 是否是一个标准的Email地址
22      */
23     private boolean email;
24 
25     /**
26      * 默认无参的构造函数
27      */
28     public Email() {
29 
30     }
31 
32     /**
33      * 构造方法
34      * 
35      * @param mailAdd
36      *            Email地址
37      * @return
38      */
39     public Email(String mailAdd) {
40         this.mailAdd = mailAdd;
41     }
42 
43     /**
44      * 是否是一个标准的Email地址
45      * 
46      * @return 布尔值
47      */
48     public boolean isEmail() {
49         String regex = "\\w+([-+.']\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*";
50         if (mailAdd.matches(regex)) {
51             email = true;
52         }
53         return email;
54     }
55 
56     public String getMailAdd() {
57         return mailAdd;
58     }
59 
60     public void setMailAdd(String mailAdd) {
61         this.mailAdd = mailAdd;
62     }
63 
64 }

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2、日期显示

jsp页面

 1 <style type="text/css">
 2 #clock {
 3     width: 420px;
 4     height: 80px;
 5     background: #E0E0E0;
 6     font-size: 25px;
 7     font-weight: bold;
 8     border: solid 5px orange;
 9     padding: 20px;
10 }
11 
12 #week {
13     padding-top: 15px;
14     color: #0080FF;
15 }
16 </style>
17 <meta http-equiv="Refresh" content="1"><%-- 页面1秒刷新一次，显示出时间效果 --%>
18 </head>
19 <body>
20     <jsp:useBean id="date" class="com.lyq.bean.DateBean"
21         scope="application"></jsp:useBean>
22     <center>
23         <div id="clock">
24             <div id="time">
25                 <jsp:getProperty property="dateTime" name="date" />
26             </div>
27             <div id="week">
28                 <jsp:getProperty property="week" name="date" />
29             </div>
30         </div>
31     </center>
32 </body>

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javabean代码

 1 package com.lyq.bean;
 2 
 3 import java.text.SimpleDateFormat;
 4 import java.util.Calendar;
 5 import java.util.Date;
 6 
 7 /**
 8  * 日期处理类
 9  * @author Administrator
10  *
11  */
12 public class DateBean {
13     private String dateTime;
14     private String week;
15     private Calendar calendar = Calendar.getInstance();
16 
17     public String getDateTime() {
18         Date currDate = Calendar.getInstance().getTime();
19         SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH点mm分ss秒");
20         this.dateTime = sdf.format(currDate);
21         return this.dateTime;
22     }
23 
24     public String getWeek() {
25         String[] weeks = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };
26         int index = calendar.get(Calendar.DAY_OF_WEEK); // 获取一星期的某天
27         this.week = weeks[index - 1];
28         return this.week;
29     }
30 }

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3、数组/字符串处理

jsp页面

 1 <form action="paper_reg.jsp" method="post">
 2         <div>
 3             <h1>调查问卷</h1>
 4             <hr />
 5             <ul>
 6                 <li>你经常用哪些编程语言开发程序：</li>
 7                 <li><input type="checkbox" name="languages" value="JAVA" id="languages0" /><label for="languages0">JAVA</label>
 8                     <input type="checkbox" name="languages" value="PHP" id="languages1" /><label for="languages1">PHP</label> 
 9                     <input type="checkbox" name="languages" value=".NET" id="languages2" /><label for="languages2">.NET</label>
10                     <input type="checkbox" name="languages" value="VC++" id="languages3" /><label for="languages3">VC++</label>
11                     </li>
12             </ul>
13             <ul>
14                 <li>你目前掌握的技术：</li>
15                 <li><input type="checkbox" name="technics" value="HTML" />HTML
16                     <input type="checkbox" name="technics" value="JAVABEAN" />JAVABEAN 
17                     <input type="checkbox" name="technics" value="JSP" />JSP 
18                     <input type="checkbox" name="technics" value="SERVLET" />SERVLET</li>
19             </ul>
20             <ul>
21                 <li>在学习中哪一部分感觉有困难：</li>
22                 <li><input type="checkbox" name="parts" value="JSP" />JSP
23                     <input type="checkbox" name="parts" value="STRUTS" />"STRUTS"
24             </ul>
25             <input type="submit" value="提交" />
26         </div>
27     </form>

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 1 <body>
 2     <jsp:useBean id="paper" class="com.lyq.bean.Paper"></jsp:useBean>
 3     <jsp:useBean id="convert" class="com.lyq.bean.Convert"></jsp:useBean>
 4     <jsp:setProperty property="*" name="paper" />
 5     <div>
 6         <h1>调查结果</h1>
 7         <hr />
 8         <li>你经常使用的编程语言：<%= convert.arr2Str(paper.getLanguages()) %></li>
 9         <li>你目前掌握的技术：<%= convert.arr2Str(paper.getTechnics()) %></li>
10         <li>在学习中哪一部分感觉有困难：<%= convert.arr2Str(paper.getParts()) %></li>
11     </div>
12 </body>

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javabean代码

 1 package com.lyq.bean;
 2 
 3 import java.io.Serializable;
 4 
 5 /**
 6  * 数组转字符串
 7  * 
 8  * @author Administrator
 9  *
10  */
11 public class Paper implements Serializable {
12     private static final long serialVersionUID = 1L;
13     /**
14      * 语言
15      */
16     private String[] languages;
17     /**
18      * 技术
19      */
20     private String[] technics;
21     /**
22      * 难点
23      */
24     private String[] parts;
25 
26     public Paper() {
27 
28     }
29 
30     public String[] getLanguages() {
31         return this.languages;
32     }
33 
34     public void setLanguages(String[] languages) {
35         this.languages = languages;
36     }
37 
38     public String[] getTechnics() {
39         return this.technics;
40     }
41 
42     public void setTechnics(String[] technics) {
43         this.technics = technics;
44     }
45 
46     public String[] getParts() {
47         return this.parts;
48     }
49 
50     public void setParts(String[] parts) {
51         this.parts = parts;
52     }
53 }

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 1 package com.lyq.bean;
 2 
 3 public class Convert {
 4     /**
 5      * 将数组转成字符串
 6      * 
 7      * @param arr
 8      *            数组
 9      * @return 字符串
10      */
11     public String arr2Str(String[] arr) {
12         StringBuffer sb = new StringBuffer();  //StringBuffer是可变长的对象，比使用String拼接效率更高
13         if (arr == null || arr.length == 0)
14             return sb.toString();
15         for (String s : arr) {
16             sb.append(s);
17             sb.append(",");
18         }
19         if (sb.length() > 0)
20             sb = sb.deleteCharAt(sb.length() - 1);
21         return sb.toString();
22     }
23 }

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4、不同方法接收页面参数

jsp页面

1 <form action="person_reg.jsp" method="post">
2 <b>添加用户信息</b><br />
3 姓名：<input type="text" id="username" name="username" /><br />
4 年龄：<input type="text" id="age" name="age" /><br />
5 性别：<input type="text" id="sex" name="sex" /><br />
6 住址：<input type="text" id="add" name="add" /><br />
7 <input type="submit" value="提交" />
8 </form>

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 1 <body>
 2     <%
 3         request.setCharacterEncoding("UTF-8"); //防止中文乱码
 4     %>
 5     <jsp:useBean id="person" class="com.lyq.bean.Person" scope="page">
 6         <jsp:setProperty name="person" property="*" /><%-- 使用*接收所有参数，使用这种方式要求表单中的属性名与JavaBean的属性名一致 --%>
 7         <jsp:setProperty name="person" property="name" param="username" /><%--如果表单中的属性名(即参数)与JavaBean的属性名一致，则用param对其赋值 --%>
 8     </jsp:useBean>
 9     <div>
10         <ul>
11             <li>姓名：<jsp:getProperty property="name" name="person" /></li>
12             <li>年龄：<jsp:getProperty property="age" name="person" /></li>
13             <li>性别：<jsp:getProperty property="sex" name="person" /></li>
14             <li>住址：<jsp:getProperty property="add" name="person" /></li>
15         </ul>
16     </div>
17 </body>

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javabean代码

 1 package com.lyq.bean;
 2 
 3 /**
 4  * 人员信息
 5  * @author Administrator
 6  *
 7  */
 8 public class Person {
 9     /**
10      * 姓名
11      */
12     private String name;
13     /**
14      * 年龄
15      */
16     private int age;
17     /**
18      * 性别
19      */
20     private String sex;
21     /**
22      * 住址
23      */
24     private String add;
25 
26     public String getName() {
27         return this.name;
28     }
29 
30     public void setName(String name) {
31         this.name = name;
32     }
33 
34     public int getAge() {
35         return this.age;
36     }
37 
38     public void setAge(int age) {
39         this.age = age;
40     }
41 
42     public String getSex() {
43         return this.sex;
44     }
45 
46     public void setSex(String sex) {
47         this.sex = sex;
48     }
49 
50     public String getAdd() {
51         return this.add;
52     }
53 
54     public void setAdd(String add) {
55         this.add = add;
56     }
57 }