实践笔记：JavaBean的思考和实践
目标：
- JavaBean的作用和实现
- 制作第一个网页
环境：基于前文所述
JavaBean是什么?
javaBean是这样一种类：
- 一个公共类，public
- 私有的实例变量，private
- 通过getter/setter来访问
javaBean用于实现业务逻辑与显示代码的分离。
javaBean如何与显示代码交互呢？通过JSP内置对象request来获得初始值，通过setProperty方法设置初始值，通过getProperty方法输出初始值，分别调用setter和getter。
实例：表单提交和显示
Person.java
package cn.com.jsp;
public class Person {
private String name;
private int age;
private String sex;
private boolean secret;
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 boolean isSecret() {
return secret;
}
public void setSecret(boolean secret) {
this.secret = secret;
}
}
useBean.html
<!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=UTF-8"> <title>Java Bean Action</title> <link rel = 'stylesheet' type = 'text/css' href = 'css/style.css'> </head> <body> <br/> <div align = "center"> <form action = "useBean.jsp" method = "post"> <legend>登陆</legend> <table align = "center" width = "400"> <tr> <td align = "right" style = "font-weight:bold;">姓名:</td> <td><input type = "text" name = "name" value = "" style = "width:200px;"/></td> </tr> <tr> <td align = "right" style = "font-weight:bold;">年龄:</td> <td><input type = "text" name = "age" value = "" style = "width:200px;"/></td> </tr> <tr> <td align = "right" style = "font-weight:bold;">性别:</td> <td> <input type = "radio" name = "sex" value = "Male"/>Male <input type = "radio" name = "sex" value = "Female"/>Female </td> </tr> <tr> <td align = "right" style = "font-weight:bold;"></td> <td><input type = "submit" name = "search" value = "提交用户信息" class = "button"/></td> </tr> </table> </form> </div> </body> </html>
form标记一个表单，这个页面通过表单提交用户信息，第14行action属性指出将表单信息通过HTTP的POST指令发送给useBean.jsp。request对象就定义了信息传递的结构。
useBean.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>JavaBean Actions</title>
<link rel = 'stylesheet' type = 'text/css' href = 'css/style.css'>
</head>
<body>
<jsp:useBean id="person" class = "cn.com.jsp.Person" scope = "page"/>
<jsp:setProperty name="person" property="*"/>
<div align = "center">
<form action = "" method = "get">
<legend>信息</legend>
<table align = "center" width = "400">
<tr>
<td align = "right" style = "font-weight:bold;">姓名:</td>
<td>
<jsp:getProperty name = "person" property = "name"/>
</td>
</tr>
<tr>
<td align = "right" style = "font-weight:bold;">年龄:</td>
<td>
<jsp:getProperty name = "person" property = "age"/>
</td>
</tr>
<tr>
<td align = "right" style = "font-weight:bold;">性别:</td>
<td>
<jsp:getProperty name = "person" property = "sex"/>
</td>
</tr>
<tr>
<td align = "right" style = "font-weight:bold;">性别:</td>
<td>
<input type="button" onclick = "history.go(-1);" value = "返回" class = "button">
</td>
</tr>
</table>
</form>
</div>
</body>
</html>
第12行定义一个Person类的对象，第14行调用setProperty方法初始化这个对象，注意request信息的结构化。
目录结构：
其中Java Resources里放要编译的文件，WebContent里放脚本文件。很明显，采用javaBean后使得脚本语言和java语言文件分离了