欧阳俊曦精通Struts / II
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常用的Struts 2.0的标志(Tag)介绍
- 非UI标志
- if、elseif和else 描述:执行基本的条件流转。参数:名称 必需 默认 类型 描述 备注 test 是 Boolean 决定标志里内容是否显示的表达式 else标志没有这个参数 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Condition Flow</title> </head> <body> <h3>Condition Flow</h3> <!-- 这里有点小技巧: 本来可以用#parameters.name[0]来获得,请求中name的值。但是,在我实现include例子时, 无论我用param标志给name赋任何值,#parameters里面不会含有任何值,所以#parameters.name也为空值。 其原因为: 当使用include标志时,被包含的页面(included)里#parameters拿到的是包含页面里的请求参数。 因此,这里必须手工调用request.getParameter("name")。 --> <s:set name="name" value="<%= "'" + request.getParameter("name") + "'" %>" /> <s:if test="#name == 'Max'"> Max's file here </s:if> <s:elseif test="#name == 'Scott'"> Scott's file here </s:elseif> <s:else> Other's file here </s:else> </body> </html>例1 condition.jsp
- iterator 描述:用于遍历集合(java.util.Collection)或枚举值(java.util.Iterator)。参数:名称 必需 默认 类型 描述 status 否 String 如果设置此参数,一个IteratorStatus的实例将会压入每个遍历的堆栈 value 否 Object/String 要遍历的可枚举的(iteratable)数据源,或者将放入新列表(List)的对象 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:
<%@ page contentType="text/html; charset=UTF-8" %>
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<% List list = new ArrayList(); list.add("Max"); list.add("Scott"); list.add("Jeffry"); list.add("Joe"); list.add("Kelvin"); request.setAttribute("names", list); %>
<html>
<head>
<title>Iterator</title> </head> <body> <h3>Names: </h3> <!-- 1、此处的空property元素用于获得当前iterator的值 2、status被设成stuts,在iterator的里面就可以通过#stuts取得IteratorStatus的对象。IteratorStatus类包含当前序号信息,如是否第一个或最后一个,是否为奇数序号。这些信息在我们做格式化的时候,显得非常有用。 --> <ol> <s:iterator value="#request.names" status="stuts"> <s:if test="#stuts.odd == true"> <li>White <s:property /></li> </s:if> <s:else> <li style="background-color:gray"><s:property /></li> </s:else> </s:iterator> </ol> </body> </html>
- i18n 描述:加载资源包到值堆栈。它可以允许text标志访问任何资源包的信息,而不只当前action相关联的资源包。参数:名称 必需 默认 类型 描述 value 是 Object/String 资源包的类路径(如com.xxxx.resources.AppMsg) id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:HelloWorld=Hello Wrold!例3 classes/ ApplicationMessages.properties<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Internationization</title> </head> <body> <h3> <s:i18n name="ApplicationMessages"> <s:text name="HelloWorld" /> </s:i18n> </h3> </body> </html>例3 i18n.jsp
- include 描述:包含一个servlet的输出(servlet或jsp的页面)。参数:名称 必需 默认 类型 描述 value 是 String 要包含的jsp或servlet id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Iterator</title> </head> <body> <h3>Interator Page</h3> <s:include value="/condition.jsp"> <s:param name="name">Max</s:param> </s:include> <h3>i18n</h3> <s:include value="/i18n.jsp" /> </body> </html>例4 include.jsp
- param 描述:为其他标签提供参数,比如include标签和bean标签. 参数的name属性是可选的,如果提供,会调用Component的方法addParameter(String, Object), 如果不提供,则外层嵌套标签必须实现UnnamedParametric接口(如TextTag)。value的提供有两种方式,通过value属性或者标签中间的text,不同之处我们看一下例子:<param name="color">blue</param><!-- (A) --><param name="color" value="blue"/><!-- (B) --> (A)参数值会以String的格式放入statck. (B)该值会以java.lang.Object的格式放入statck.参数:名称 必需 默认 类型 描述 name 否 String 参数名 value 否 String value表达式 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:请参考例4。
- set 描述: set标签赋予变量一个特定范围内的值。当希望给一个变量赋一个复杂的表达式,每次访问该变量而不是复杂的表达式时用到。其在两种情况下非常有用: 复杂的表达式很耗时 (性能提升) 或者很难理解 (代码可读性提高)。参数:名称 必需 默认 类型 描述 name 是 String 变量名字 scope 否 String 变量作用域,可以为application, session, request, page, 或action. value 否 Object/String 将会赋给变量的值 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:请参考例1。
- text 描述:支持国际化信息的标签。国际化信息必须放在一个和当前action同名的resource bundle中,如果没有找到相应message,tag body将被当作默认message,如果没有tag body,message的name会被作为默认message。参数:名称 必需 默认 类型 描述 name 是 String 资源属性的名字 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:请参考例3。
- url 描述:该标签用于创建url,可以通过"param"标签提供request参数。当includeParams的值时'all'或者'get', param标签中定义的参数将有优先权,也就是说其会覆盖其他同名参数的值。参数: 略例子:<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>URL</title> </head> <body> <h3>URL</h3> <a href='<s:url value="/i18n.jsp" />'>i18n</a><br /> <s:url id="url" value="/condition.jsp"> <s:param name="name">Max</s:param> </s:url> <s:a href="%{url}">if/elseif/else</s:a> </body> </html>例5 url.jsp
- property 描述:得到'value'的属性,如果value没提供,默认为堆栈顶端的元素。参数:名称 必需 默认 类型 描述 default 否 String 如果属性是null则显示的default值 escape 否 true Booelean 是否escape HTML value 否 栈顶 Object 要显示的值 id 否 Object/String 用来标识元素的id。在UI和表单中为HTML的id属性例子:请参考例2。
- if、elseif和else
- UI标志 UI标志又可以分为表单UI和非表单UI两部分。表单UI部分基本与Struts 1.x相同,都是对HTML表单元素的包装。不过,Struts 2.0加了几个我们经常在项目中用到的控件如:datepicker、doubleselect、timepicker、optiontransferselect等。因为这些标志很多都经常用到,而且参数也很多,要在一篇文章详细说明并非易事。需要深入了解这些标志的朋友,可以到以下查看以下网址: http://wiki.javascud.org/display/ww2cndoc/Tags WebWork2文档中文化计划(中文) http://cwiki.apache.org/WW/tag-reference.html Tag Developers Guide(英文)本文有相当的内容也来自这两处。在此,我虽然不能够详细讲述这些标志,但是可以与大家分享一个来Struts 2.0 Show Case一个例子。/**//* * $Id: UITagExample.java 420385 2006-07-10 00:57:05Z mrdon $ * * Copyright 2006 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.struts2.showcase; import org.apache.struts2.ServletActionContext; import com.opensymphony.xwork2.ActionSupport; import com.opensymphony.xwork2.Validateable; import com.opensymphony.xwork2.util.OgnlValueStack; import java.util.ArrayList; import java.util.Collections; import java.util.Date; import java.util.HashMap; import java.util.List; import java.util.Map; import java.io.File; /** *//** */ public class UITagExample extends ActionSupport implements Validateable { private static final long serialVersionUID = -94044809860988047L; String name; Date birthday; String bio; String favoriteColor; List friends; boolean legalAge; String state; String region; File picture; String pictureContentType; String pictureFileName; String favouriteLanguage; String favouriteVehicalType = "MotorcycleKey"; String favouriteVehicalSpecific = "YamahaKey"; List leftSideCartoonCharacters; List rightSideCartoonCharacters; List favouriteLanguages = new ArrayList(); List vehicalTypeList = new ArrayList(); Map vehicalSpecificMap = new HashMap(); String thoughts; public UITagExample() { favouriteLanguages.add(new Language("EnglishKey", "English Language")); favouriteLanguages.add(new Language("FrenchKey", "French Language")); favouriteLanguages.add(new Language("SpanishKey", "Spanish Language")); VehicalType car = new VehicalType("CarKey", "Car"); VehicalType motorcycle = new VehicalType("MotorcycleKey", "Motorcycle"); vehicalTypeList.add(car); vehicalTypeList.add(motorcycle); List cars = new ArrayList(); cars.add(new VehicalSpecific("MercedesKey", "Mercedes")); cars.add(new VehicalSpecific("HondaKey", "Honda")); cars.add(new VehicalSpecific("FordKey", "Ford")); List motorcycles = new ArrayList(); motorcycles.add(new VehicalSpecific("SuzukiKey", "Suzuki")); motorcycles.add(new VehicalSpecific("YamahaKey", "Yamaha")); vehicalSpecificMap.put(car, cars); vehicalSpecificMap.put(motorcycle, motorcycles); } public List getLeftSideCartoonCharacters() { return leftSideCartoonCharacters; } public void setLeftSideCartoonCharacters(List leftSideCartoonCharacters) { this.leftSideCartoonCharacters = leftSideCartoonCharacters; } public List getRightSideCartoonCharacters() { return rightSideCartoonCharacters; } public void setRightSideCartoonCharacters(List rightSideCartoonCharacters) { this.rightSideCartoonCharacters = rightSideCartoonCharacters; } public String getFavouriteVehicalType() { return favouriteVehicalType; } public void setFavouriteVehicalType(String favouriteVehicalType) { this.favouriteVehicalType = favouriteVehicalType; } public String getFavouriteVehicalSpecific() { return favouriteVehicalSpecific; } public void setFavouriteVehicalSpecific(String favouriteVehicalSpecific) { this.favouriteVehicalSpecific = favouriteVehicalSpecific; } public List getVehicalTypeList() { return vehicalTypeList; } public List getVehicalSpecificList() { OgnlValueStack stack = ServletActionContext.getValueStack(ServletActionContext.getRequest()); Object vehicalType = stack.findValue("top"); if (vehicalType != null && vehicalType instanceof VehicalType) { List l = (List) vehicalSpecificMap.get(vehicalType); return l; } return Collections.EMPTY_LIST; } public List getFavouriteLanguages() { return favouriteLanguages; } public String execute() throws Exception { return SUCCESS; } /**//* Getters and Setters */ public String doSubmit() { return SUCCESS; } // === inner class public static class Language { String description; String key; public Language(String key, String description) { this.key = key; this.description = description; } public String getKey() { return key; } public String getDescription() { return description; } } public static class VehicalType { String key; String description; public VehicalType(String key, String description) { this.key = key; this.description = description; } public String getKey() { return this.key; } public String getDescription() { return this.description; } public boolean equals(Object obj) { if (! (obj instanceof VehicalType)) { return false; } else { return key.equals(((VehicalType)obj).getKey()); } } public int hashCode() { return key.hashCode(); } } public static class VehicalSpecific { String key; String description; public VehicalSpecific(String key, String description) { this.key = key; this.description = description; } public String getKey() { return this.key; } public String getDescription() { return this.description; } public boolean equals(Object obj) { if (! (obj instanceof VehicalSpecific)) { return false; } else { return key.equals(((VehicalSpecific)obj).getKey()); } } public int hashCode() { return key.hashCode(); } } }例6 org.apache.struts2.showcase.UITagExample.java<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <html> <head> <title>UI Tags Example</title> <s:head/> </head> <body> <s:actionerror/> <s:actionmessage/> <s:fielderror /> <s:form action="exampleSubmit" method="post" enctype="multipart/form-data" tooltipConfig="#{'jsTooltipEnabled':'true'}"> <s:textfield label="Name" name="name" tooltip="Enter your Name here" /> <s:datepicker tooltip="Select Your Birthday" label="Birthday" name="birthday" /> <s:textarea tooltip="Enter your Biography" label="Biograph" name="bio" cols="20" rows="3"/> <s:select tooltip="Choose Your Favourite Color" label="Favorite Color" list="{'Red', 'Blue', 'Green'}" name="favoriteColor" emptyOption="true" headerKey="None" headerValue="None"/> <s:select tooltip="Choose Your Favourite Language" label="Favourite Language" list="favouriteLanguages" name="favouriteLanguage" listKey="key" listValue="description" emptyOption="true" headerKey="None" headerValue="None"/> <s:checkboxlist tooltip="Choose your Friends" label="Friends" list="{'Patrick', 'Jason', 'Jay', 'Toby', 'Rene'}" name="friends"/> <s:checkbox tooltip="Confirmed that your are Over 18" label="Age 18+" name="legalAge"/> <s:doubleselect tooltip="Choose Your State" label="State" name="region" list="{'North', 'South'}" value="'South'" doubleValue="'Florida'" doubleList="top == 'North' ? {'Oregon', 'Washington'} : {'Texas', 'Florida'}" doubleName="state" headerKey="-1" headerValue="---------- Please Select ----------" emptyOption="true" /> <s:doubleselect tooltip="Choose your Vehical" label="Favourite Vehical" name="favouriteVehicalType" list="vehicalTypeList" listKey="key" listValue="description" value="'MotorcycleKey'" doubleValue="'YamahaKey'" doubleList="vehicalSpecificList" doubleListKey="key" doubleListValue="description" doubleName="favouriteVehicalSpecific" headerKey="-1" headerValue="---------- Please Select ----------" emptyOption="true" /> <s:file tooltip="Upload Your Picture" label="Picture" name="picture" /> <s:optiontransferselect tooltip="Select Your Favourite Cartoon Characters" label="Favourite Cartoons Characters" name="leftSideCartoonCharacters" leftTitle="Left Title" rightTitle="Right Title" list="{'Popeye', 'He-Man', 'Spiderman'}" multiple="true" headerKey="headerKey" headerValue="--- Please Select ---" emptyOption="true" doubleList="{'Superman', 'Mickey Mouse', 'Donald Duck'}" doubleName="rightSideCartoonCharacters" doubleHeaderKey="doubleHeaderKey" doubleHeaderValue="--- Please Select ---" doubleEmptyOption="true" doubleMultiple="true" /> <s:textarea label="Your Thougths" name="thoughts" tooltip="Enter your thoughts here" /> <s:submit onclick="alert('aaaa');" /> <s:reset onclick="alert('bbbb');" /> </s:form> </body> </html>例6 example.jsp<action name="example" class="org.apache.struts2.showcase.UITagExample"> <result>example.jsp</result> <result name="input">example.jsp</result> </action>例6 struts.xml代码片段
http://johnoyoung.blog.sohu.com/90691910.html http://blog.sina.com.cn/s/blog_51e1d40e0100aadc.html http://blog.21cn.com/johnoyoung/article/51468 http://hi.baidu.com/johnoyoung/blog/item/76c5be6008c1e0da8cb10d00.html http://johnoyoung.bokee.com/viewdiary.32408821.html http://blog.yesky.com/blog/junhay/archive/2008/06/21/1855338.html
http://tieba.baidu.com/f?kz=416118784
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