概述
该技术已过时
jsp 已经过时,是因为代码杂糅在一起,没有做到完美的分离.不利于后期的维护
java bean 过时的原因在于面条代码的存在,即,各种代码杂乱的糅合在一起.
特点
组件式编程 步骤封装成为组件,需要那个的时候,直接调用组件即可.增加复用性
标准目录结构
WEB-INF
该目录为web目录中最安全的文件夹.保存各种类,第三方jar包,配置文件.
WEB-XML
web部署的描述符
classes
保存所有hacabean
lib
第上方jar包
tags
保存所有标签文件
jsp
保存jsp文件
css
保存样式表文件
images
保存图片文件
page导入JavaBean
package demo; public class demo { public String name; public String age; public demo(){ } public void setName(String name){ this.name = name; } public void setAge(String age){ this.age = age; } public String getName(){ return this.name; } public String getAge(){ return this.age; } } <%-- Created by IntelliJ IDEA. User: ming Date: 19-3-14 Time: 下午9:19 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ page import="demo.demo" %> <html> <head> <title>Title</title> </head> <body> <% demo demo = new demo(); demo.setAge("12"); demo.setName("ming"); %> <%=demo.getName()%> <%=demo.getAge()%> </body> </html> JavaBean与表单
同jsp 直接传参即可
jsp:useBean指令
使用jsp:useBean指令可以直接调用类
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-14 Time: 下午9:19 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="demo" scope="page" class="demo.demo"/> <html> <head> <title>Title</title> </head> <body> <% demo.setName("ming"); demo.setAge("12"); %> <%=demo.getAge()%> <%=demo.getName()%> </body> </html> JavaBean范围
使用scope属性标记范围 当为post的时候,表示为只在本页生效. 当为request的时候,表示在一次页面跳转,不会重新实例化对象 当为session,表示对象的生命周期为整个会话 当为application的时候,表示为所有用户共同拥有这个对象.即为单例模式
栗子
注册验证
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-15 Time: 上午12:53 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>用户注册页</title> </head> <body> <jsp:useBean id="reg" scope="request" class="com.ming.Register"/> <form action="./check.jsp" method="post"> 用户名<input type="text" name="name" value="<jsp:getProperty name="reg" property="name"/>"/> <%=reg.getErrorMsg("errname")%> 年龄<input type="text" name="age" value="<jsp:getProperty name="reg" property="age"/>"/> <%=reg.getErrorMsg("errage")%> E-Mail<input type="text" name="email" value="<jsp:getProperty name="reg" property="email"/>"/> <%=reg.getErrorMsg("erremail")%> <input type="submit" value="注册"/> <input type="reset" value="重置"/> </form> </body> </html> <%-- Created by IntelliJ IDEA. User: ming Date: 19-3-15 Time: 上午2:04 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <jsp:useBean id="reg" scope="request" class="com.ming.Register"/> 用户名 <jsp:getProperty name="reg" property="name"/> 年龄 <jsp:getProperty name="reg" property="age"/> E-Mail <jsp:getProperty name="reg" property="email"/> </body> </html> <%-- Created by IntelliJ IDEA. User: ming Date: 19-3-15 Time: 上午12:55 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>信息验证中</title> </head> <body> <jsp:useBean id="reg" scope="request" class="com.ming.Register"/> <!-- 属性自动赋值 --> <jsp:setProperty name="reg" property="*"/> <% // 进行验证 if(reg.isVaildate()){ %> <jsp:forward page="sucess.jsp"/> <% }else{ %> <jsp:forward page="index.jsp"/> <% } %> </body> </html> package com.ming; import java.util.HashMap; import java.util.Map; public class Register { private String name; private String age; private String email; private Map<String, String> errors = null; public Register(){ this.name = ""; this.age = ""; this.email = ""; this.errors = new HashMap<String, String>(); } public boolean isVaildate(){ boolean flag = true; // 验证name合法 if(!this.name.matches("\\w{6,15}")){ flag = false; this.name = ""; errors.put("errname", "用户名需要为6-15位字母或数字"); } if(!this.email.matches("\\w+@\\w+\\.\\w+\\.?\\w*")){ flag = false; this.email = ""; errors.put("erremail", "输入email地址错误"); } if(!this.age.matches("\\d+")){ flag = false; this.age = ""; errors.put("errage", "年龄只能是数字"); } return flag; } // 取出错误信息 public String getErrorMsg(String key){ String value = this.errors.get(key); return value == null ? "" : value; } public String getName() { return name; } public String getAge() { return age; } public Map<String, String> getErrors() { return errors; } public void setName(String name) { this.name = name; } public void setErrors(Map<String, String> errors) { this.errors = errors; } public void setEmail(String email) { this.email = email; } public void setAge(String age) { this.age = age; } public String getEmail() { return email; } } ![Java小案例——随机数猜测随机数猜测[图]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)