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Struts 2

Struts 2. Web Framework. 提纲. struts 基本概念 标签 tag Ognl 国际化 验证 类型转换 拦截器. Hello. Struts 项目发布结构. 页面流转. Index.html: ----------------------- <a href =" HelloWorld.action ">hello</a>. hello.jsp: ----------------------- Hello:<s:property value="name"/>. hello_form.jsp:

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Struts 2

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  1. Struts 2 Web Framework

  2. 提纲 • struts基本概念 • 标签tag • Ognl • 国际化 • 验证 • 类型转换 • 拦截器

  3. Hello

  4. Struts 项目发布结构

  5. 页面流转 Index.html: ----------------------- <a href="HelloWorld.action">hello</a> hello.jsp: ----------------------- Hello:<s:property value="name"/> hello_form.jsp: ----------------------- <h3>Say "Hello" to: </h3> <s:form action="HelloWorld"> <s:textfield label="Name" name="name" /> <s:submit/> </s:form>

  6. Web.xml <web-app id="StrutsHello" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Struts2 Hello</display-name> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>

  7. Struts.xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.enable.DynamicMethodInvocation" value="true" /> <constant name="struts.devMode" value="true" /> <package name="example" namespace="/" extends="struts-default"> <action name="HelloWorld" class="hello.HelloWorld"> <result name="input">/WEB-INF/jsp/hello_form.jsp</result> <result name="success">/WEB-INF/jsp/hello.jsp</result> </action> </package> </struts>

  8. HelloWorld.java • public class HelloWorld extends ActionSupport { • private String name=""; • public String execute() throws Exception { • if (isInvalid(getName())) return INPUT; • return SUCCESS; • } • private boolean isInvalid(String value) { • return (value == null || value.length() == 0); • } • public String getName() { • return name; • } • public void setName(String name) { • this.name = name; • } • }

  9. 直观感受: • Struts帮我们把Http请求填充到Action对象中 • Struts帮我们把Http响应中的动态数据绑定到界面，提供一组标签来丰富web开发。 • Struts接收所有请求然后根据配置交付给处理者(action),处理者扮演控制器装载数据并呈现页面。 • Struts 提供页面流控制,避免直接访问jsp页面来装载数据,分离业务计算和页面呈现。(试试给name提供一个缺省值) • 有点复杂,后面我们会尝试简化部分编程模型。

  10. 基于Struts的web编程建议 • 避免直接访问任意的jsp页面 • 使用Struts标签替代html标签 • 避免在页面上进行业务计算，而应由Action提供计算好的数据

  11. 基本概念

  12. 主要配置文件 我们要参考的 • struts2_core_xx.jar/org/apache/struts2/default.properties • struts2_core_xx.jar/struts-default.xml 我们要配置的 • web.xml • struts.xml

  13. struts.xml /struts-2.0.dtd 目前最关心的: • constant • include • package action result-types

  14. 体系结构

  15. Action是Struts的核心 • Mvc 2模型 • Struts请求响应流程 • 减少对ServletApi的直接依赖(参考ActionContext) • 页面和Action的数据关系(更多内容参考后面的ognl) • 更多的Action使用和配置范例。

  16. Result <action name="register" class="example.register.RegisterAction" > <result name=“input“ >register.jsp</result><!—默认结果类型就是dispatcher --> <result name="success" type="dispatcher">register-result.jsp</result> </action> public class RegisterAction extends ActionSupport{ public String execute(){ //检查… return “success”; } }

  17. Result • Result 是一个Action方法返回的字符串 • Result被设置为一种视图 • Result 类型是com.opensymphony.xwork2. Result的实现类 • type=“dispatcher” : org.apache.struts2.dispatcher.ServletDispatcherResult: 最终会执行类似下面代码: request.getRequestDispatcher(“register.jsp”).include(request, response); 或： request.getRequestDispatcher(“register.jsp”).forward(request, response);

  18. com.opensymphony.xwork2. Action预定义结果 • String SUCCESS = "success"; • String NONE = "none"; • String ERROR = "error"; • String INPUT = "input"; • String LOGIN = "login";

  19. ResultTypes(struts-default.xml) • Dispatcher Result <result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/> • Redirect Result <result-type name="redirect" class="org.apache.struts2.dispatcher.ServletRedirectResult"/> • Redirect Action Result <result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/>

  20. Annotation/ Xml/约定 开启约定配置: • struts.enable.DynamicMethodInvocation=true 当前的2个Annotation • Result • Results 开启约定配置的问题: • 包分布 • 危险的方法探测? • 权衡

  21. 线程模型 • Action不同于servlet

  22. ActionContext • ActionContext • ServletActionContext

  23. Tag

  24. Control Tags • if/elseif/esle * • append • generator • iterator * • merge • sort • subset

  25. Data Tags • a * • action • bean • date • debug * • i18n • include • param * • property　* • push • set • text • url　*

  26. Form UI Tags • checkbox * • checkboxlist * • combobox * • doubleselect • head * • file * • form * • hidden * • label * • optiontransferselect • optgroup • password * • radio * • reset * • select * • submit * • textarea * • textfield * • token * • updownselect

  27. Non-Form UI Tags • actionerror * • actionmessage • component • div • fielderror • table • tabbedPanel • tree • treenode

  28. Ajax Tags • a • autocompleter • bind • datetimepicker * • head • submit

  29. 问题 • 各标签中容易混淆的id/name/var属性 • Ajax tags

  30. 验证 validation

  31. 缺省验证器 • Xwork_xx.jar/com/opensymphony/xwork2/validator/validators/default.xml • com.opensymphony.xwork2.validator.Validator接口

  32. 基于Struts的web编程建议 • 通过各种方法减少xml配置。 • 避免Servletapi直接依赖:尽量使用ActionContext而非ServletActionContext

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