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10、会话管理/编程实战分析/Jsp

1 会话管理回顾

会话管理

                     1)会话管理: 管理浏览器和服务器之间的会话过程中产生的会话数据

                      2)Cookie技术: 会话数据保存在浏览器客户端。

                                          Cookie核心的API:

                                                               2.1 在服务器端创建Cookie对象

                                                                                    Cookeie cookie = new Cookie("name","value");

                                                               2.2 把cookie发送给浏览器端(通过响应头:set-cookie)

                                                                                    response.addCookie(cookie);

                                                               2.3 浏览器带着cookie信息访问服务器(通过请求头:cookie),服务器得到cookie信息

                                                                                    Cookie[] cookies = request.getCookies();

 

                                局限:

                                                     1)只能保存字符串类型,不能保存中文

                                                     2)一个cookie不能超过4kb

                     3)Session技术:会话数据保存在服务器端。(内存)

                                          Session核心的API:

                                                               3.1 创建或得到session对象  

                                                                                    HttpSession session = request.getSession(); //创建或得到session对象

                                                                                    request.getSession(false); //得到session对象

                                                               3.2 会话数据保存session对象中,和得到会话数据

                                                                                    session.setAttribute("name",Object);  保存数据

                                                                                    session.getAttribute("name")   得到数据

                                                                                                        

                                          注意:

                                                               1)session.setIntactiveInterval(时间);   设置session过期时间

                                                               2)session.invalidate()  手动销毁session对象

2 Session案例

                                用户登录场景

3 编程实战

        通讯录程序

                     软件的生命周期

              3.1 需求分析(需求分析师)

                                          功能分析:

                                                               1)添加联系人

                                                               2)修改联系人

                                                               3)删除联系人

                                                               4)查询所有联系人

                                          功能流转

        技术分享

                                                              

                                美工设计: 设计软件的静态原型

              3.2 需求设计(系统分析师/架构师/资深开发人员)

                                          1)设计实体(抽象实体)

                                                               联系人实体:

                                                                          class Contact{

                                                                                    private String id;

                                                                                    private String name;

                                                                                    private String gender;

                                                                                    private int age;

                                                                                    private String phone;

                                                                                    private String email;

                                                                                    private String qq;

                                                                          }

                                          2)设计“数据库”,(xml代替"数据库")

                                                               contact.xml

                                                                          <contactList>

                                                                                               <contact id="1">

                                                                                                         <name>张三</name>

                                                                                                         <gender>男</gender>

                                                                                                         <age>20</age>

                                                                                                         <phone>13433334444</phone>

                                                                                                          <email>zs@qq.com</email>

                                                                                                         <qq>43222222<qq>

                                                                                               </contact>

                                                                          </contactList>

                                   3)设计涉及的接口

                                                               DAO接口(数据访问对象):实体对象的CRUD方法。

                                                               项目原则: 通常一个实体对象就会对应一个DAO接口和一个DAO实现类

                                                               interface ContactDao{

                                                                          public void addContact(Contact contact);//添加联系人

                                                                          public void updateContact(Contact contact);//修改联系人

                                                                          public void deleteContact(String id);//删除联系人

                                                                          public List<Contact> findAll();  //查询所有联系人

                                                                          public Contact findById(String id);//根据编号查询联系人

                                                               }

                                          4)设计项目的目录结构

                                                               项目名称: contactSys_web

                                                               目录结构:

                                                                                    |- contactSys_web

                                                                                               |-src

                                                                                                         |-gz.itcast.contactSys_web.entity : 存放实体对象

                                                                                                         |-gz.itcast.contactSys_web.dao : 存放dao的接口

                                                                                                         |-gz.itcast.contactSys_web.dao.impl: 存放dao的实现类

                                                                                                         |-gz.itcast.contactSys_web.servlet: 存放servlet的类

                                                                                                         |-gz.itcast.contactSys_web.test: 存放单元测试类

                                                                                                         |-gz.itcast.contactSys_web.util: 存放工具类

                                                                                                         |-gz.itcast.contactSys_web.exception: 存放自定义异常类

                                                                                               |-WebRoot

                                                                                                         |-html文件

                                                                                                         |-images:目录。存放图片资源

                                                                                                         |-css:目录。存放css资源

                                                                                                         |-js:目录。存放js资源

                                                                                                                              

 

                     3.3 编码实现(软件开发工程师/攻城狮)

                                          开发顺序:

                                          设计数据库-> 实体 -> DAO接口,DAO实现-> Servlet+html页面

                     3.4 功能测试(测试攻城狮)         

               3.5 性能测试(测试攻城狮)

                     3.6 部署上线(实施攻城狮)

                     3.7 维护阶段(实施攻城狮)                   

          

4 Jsp基础

                     4.1 Jsp引入

                                           Servlet的作用: 用java语言开发动态资源的技术!!!

                                          Jsp的作用:用java语言(+html语言)开发动态资源的技术!!!

                                                     Jsp就是servlet!!!

                     4.2 Jsp的特点

                                          1)jsp的运行必须交给tomcat服务器!!!!

                                                               tomcat的work目录: tomcat服务器存放jsp运行时的临时文件

                                           2)jsp页面既可以写html代码,也可以写java代码。

                                                     (html页面不能写java代码 。而jsp页面可以写java代码)

                     4.3 体验jsp页面作用

                                          需求:显示当前时间到浏览器上

                                         

                                           可以把jsp页面当做html页面在tomcat中访问!!!

                                         

                     4.4 Jsp的执行过程

                                问题: 访问http://localhost:8080/day12/01.hello.jsp  如何显示效果?

 

                                1)访问到01.hello.jsp页面,tomcat扫描到jsp文件,在%tomcat%/work把jsp文件翻译成java源文件

                                                               (01.hello.jsp   ->   _01_hello_jsp.java) (翻译)

                                2)tomcat服务器把java源文件编译成class字节码文件 (编译)

                                                     (_01_hello_jsp.java  ->  _01_hello_jsp.class)

                                3)tomcat服务器构造_01_hello_jsp类对象

                                4)tomcat服务器调用_01_hello_jsp类里面方法,返回内容显示到浏览器。

 

           第一次访问jsp:

                                          走(1)(2)(3)(4)

           第n次访问jsp:

                                          走(4)

          

注意:

                                1)jsp文件修改了或jsp的临时文件被删除了,要重新走翻译(1)和编译(2)的过程

                                                    

                     4.5 疑问

                     问题: 为什么Jsp就是servlet!!!

                                jsp翻译的java文件:

                                          public final class _01_hello_jsp extends org.apache.jasper.runtime.HttpJspBase

    implements org.apache.jasper.runtime.JspSourceDependent {

 

                                          HttpJspBase类:

                                public abstract class org.apache.jasper.runtime.HttpJspBase extends javax.servlet.http.HttpServlet implements javax.servlet.jsp.HttpJspPage {

 

                     结论: Jsp就是一个servlet程序!!!

                            servlet的技术可以用在jsp程序中

                            jsp的技术并不是全部适用于servlet程序!

 

                    

                     Servlet的生命周期:

                                   1)构造方法(第1次访问)

                                   2)init方法(第1次访问)

                                   3)service方法

                                   4)destroy方法            

                     Jsp的生命周期

                                   1)翻译: jsp->java文件

                                   2)编译: java文件->class文件(servlet程序)

                                   3)构造方法(第1次访问)

                                   4)init方法(第1次访问):_jspInit()

                                   5)service方法:_jspService()

                                   6)destroy方法:_jspDestroy()

 

5 Jsp语法

                     5.1 Jsp模板

                                          jsp页面中的html代码就是jsp的模板

                     5.2 Jsp表达式

                                          语法:<%=变量或表达式%>

                                          作用: 向浏览器输出变量的值或表达式计算的结果

                                          注意:                

                                                     1)表达式的原理就是翻译成out.print(“变量” );通过该方法向浏览器写出内容

                                                     2)表达式后面不需要带分号结束。

                     5.3 Jsp的脚本

                                          语法:<%java代码 %>

                                          作用: 执行java代码    

                                          注意:

                                                     1)原理把脚本中java代码原封不动拷贝到_jspService方法中执行。

                     5.4 Jsp的声明

                                          语法:<%! 变量或方法 %>

                                          作用: 声明jsp的变量或方法

                                          注意:

                                                     1)变量翻译成成员变量,方法翻译成成员方法。

                     5.5 Jsp的注释

                                          语法: <%!--  jsp注释  --%>

                                          注意;

                                                     1)html的注释会被翻译和执行。而jsp的注释不能被翻译和执行。

6 Jsp的三大指令

              6.1 include指令

                                          作用: 在当前页面用于包含其他页面

                                          语法: <%@include file="common/header.jsp"%>

                                          注意:

                                                     1)原理是把被包含的页面(header.jsp)的内容翻译到包含页面(index.jsp)中,合并成翻译成一                                                    个java源文件,再编译运行!!,这种包含叫静态包含(源码包含)

                                                     2)如果使用静态包含,被包含页面中不需要出现全局的html标签了!!!(如html、head、                                                        body)

              6.2 page指令

                                          作用: 告诉tomcat服务器如何翻译jsp文件

                                           <%@ page

                  language="java"   --告诉服务器使用什么动态语言来翻译jsp文件

                  import="java.util.*" --告诉服务器java文件使用什么包

                                          导入包,多个包之间用逗号分割

                  pageEncoding="utf-8"  --告诉服务器使用什么编码翻译jsp文件(成java文件)

                contentType="text/html; charset=utf-8" 服务器发送浏览器的数据类型和内容编码

                     注意:在开发工具中,以后只需要设置pageEncoding即可解决中文乱码问题

                  errorPage="error.jsp"

                  isErrorPage="false"

                  buffer="8kb"

                  session="true"

                  isELIgnored="false"

    %>

              6.3 taglib指令

 

                                总结:

                                          1)编码实战:

                                                     1.1 servlet应用

                                                     1.2 初步了解软件开发流程

                                          2)Jsp基础

                                                     2.1 Jsp的执行原理(翻译-》编译-》servlet的生命周期)

                                                     2.2 语法(jsp表达式,jsp脚本)

                                                     2.3 指令

                                                        include指令

                                                        page指令

                                                    

                                                     

10、会话管理/编程实战分析/Jsp