Struts2的标签三大类是什么？

Struts2 标签

一 Struts标签的简介：

　　Struts2 自己封装了一套标签，比 JSTL 强大，而且与 Struts2 中的其他功能无缝结合。当然 Strust2 标签的内容很多，随着版本的升级，标签和属性越来越多。我们要掌握好核心标签及了解其他标签；根据功能可以分为：数据标签，控制标签，界面标签，其他标签；(其实如果学过标准标签库stl基本上这部分内容简单的一批)

二 Struts2 数据标签

Property 标签：输出 OGNL 表达式的值；取值

 <% request.setAttribute("name","<font color='red' >张三</font>"); %>

 <body>

     <h1>property</h1>

     <s:property value="#request.name"/><br/>

     <s:property value="#request.name2" default="某某"/><br/>

     <s:property value="#request.name" escapeHtml="false"/><br/>

 </body>

Set 标签：设置变量；

 <h1>set标签</h1>

     <s:set var="i" value="1"/><br/>

     i= <s:property value="#i"/><br/>

     <s:set var="a" value="'action的值类似于值栈（value-stack）'" scope="action"></s:set>

     <s:set var="p" value="'page的值'" scope="page"></s:set>

     <s:set var="re" value="'request值'" scope="request"></s:set>

     <s:set var="se" value="'session值'" scope="session"></s:set>

     <s:set var="app" value="'application值'" scope="application"></s:set>

     action:<s:property value="#a"/><br/>

     page:<s:property value="#attr.p"/><br/>

     request:<s:property value="#request.re"/><br/>

     session:<s:property value="#session.se"/><br/>

     application:<s:property value="#application.app"/><br/>

Bean 标签：定义 javaBean 对象；

 <h1>bean标签</h1>

     <s:bean name="com.java1234.model.Student" var="student">

         <s:param name="name" value="'张三'"></s:param>

         <s:param name="age" value="18"></s:param>

     </s:bean>

     name:<s:property value="#student.name"/><br/>

     age:<s:property value="#student.age"/><br/>

Date 标签：日期标签；

 <%  request.setAttribute("date", new Date());  %>

 <body>

     <h1>Date标签</h1>

     日期：&nbsp;&nbsp; ${date }<br/>

     日期：&nbsp;&nbsp; <s:date name="#request.date" format="yyyy-MM-dd"/>

 </body>

Debug 标签：调试标签；

 <h1>Debug标签</h1>

 <s:debug></s:debug>

Url&a 标签：超链接标签；

 <s:a action="hello" namespace="/forgroud" >

 <s:param name="name" value="'struts2'"></s:param>

 链接a

 </s:a>

Include 标签：动态包含标签；

 <s:include value="head.html"></s:include>

三 Struts2 控制标签

Ifelse 标签：条件判断标签；

 <% int age=11;   request.setAttribute("age", age);    %>

 <body>

     <h1>if else标签</h1>

      年龄：<s:property value="#request.age"/>

     <s:if test="#request.age<18">

       小于18岁

     </s:if>

     <s:elseif test="#request.age<30">

           大于18岁    小于30岁

     </s:elseif>

     <s:else>

         大于30岁

     </s:else>

 </body>

Iterator 标签：遍历标签；

 <%

     List<Student>studentList=new ArrayList<Student>();

     studentList.add(new Student(1,"张三",18));

     studentList.add(new Student(2,"李四",19));

     studentList.add(new Student(5,"王五",25));

     request.setAttribute("studentList", studentList);

 %>

 <body>

     <h1>iterator</h1>

     <table border="1">

         <tr>

             <th>序号</th>

             <th>学号</th>

             <th>姓名</th>

             <th>年龄</th>

         </tr>

         <s:iterator value="#request.studentList" var="sl" status="status">

         <tr>

             <td><s:property value="#status.index+1"/></td>

             <td><s:property value="id"/></td>

             <td><s:property value="name"/></td>

             <td><s:property value="age"/></td>

         </tr>

         </s:iterator>

     </table>

 </body>

Append 标签：叠加标签；

 <%

     List<Student>studentList=new ArrayList<Student>();

     List<Student>studentList1=new ArrayList<Student>();

     studentList.add(new Student(1,"张三",18));

     studentList.add(new Student(2,"李四",19));

     studentList.add(new Student(5,"王五",25));

     studentList1.add(new Student(6,"赵六",27));

     studentList1.add(new Student(7,"小七",28));

     request.setAttribute("studentList", studentList);

     request.setAttribute("studentList1", studentList1);

 %>

 <body>

     <s:append var="studentList2">

         <s:param value="#request.studentList"></s:param>

         <s:param value="#request.studentList1"></s:param>

     </s:append>

     <h1>iterator</h1>

     <table border="1">

         <tr>

             <th>序号</th>

             <th>学号</th>

             <th>姓名</th>

             <th>年龄</th>

         </tr>

         <s:iterator value="#request.studentList2" var="sl" status="status">

         <tr>

             <td><s:property value="#status.index+1"/></td>

             <td><s:property value="id"/></td>

             <td><s:property value="name"/></td>

             <td><s:property value="age"/></td>

         </tr>

         </s:iterator>

     </table>

 </body>

Generator 标签：分隔标签；

 <s:generator separator="," val="'张三,李四,王五'" var="nameList"></s:generator>

 　　<s:iterator value="#nameList">

       <s:property/>

    </s:iterator>

Merge 标签：组合标签；

Sort 标签：排序标签；我们使用一个简单的例子学习一下：

Model:Student类：

 public class Student {

     private String name;

     private int id;

     private int age;

     public Student() {

         super();

         // TODO Auto-generated constructor stub

     }

     public Student( int id, String name,int age) {

         super();

         this.name = name;

         this.id = id;

         this.age = age;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this.name = name;

     }

     public int getId() {

         return id;

     }

     public void setId(int id) {

         this.id = id;

     }

     public int getAge() {

         return age;

     }

     public void setAge(int age) {

         this.age = age;

     }

 }

排序类：com.java1234.compator.MyComparator代码：

  public class MyComparator  implements Comparator<Student>{

     public int compare(Student s1,Student s2){

         if(s1.getAge()>s2.getAge()){

             return 1;

         }else if(s1.getAge()<s2.getAge()){

             return -1;

         }else{

             return 0;

         }

     }

 }

 <%

     List<Student>studentList=new ArrayList<Student>();

     studentList.add(new Student(1,"张三",18));

     studentList.add(new Student(2,"李四",19));

     studentList.add(new Student(5,"王五",25));

     studentList.add(new Student(6,"王五",17));

     studentList.add(new Student(7,"王五",19));

     request.setAttribute("studentList", studentList);

 %>

 <body>

     <h1>iterator</h1>

     <s:bean id="Mycomparator" name="com.java1234.compator.MyComparator"></s:bean>

     <table border="1">

         <tr>

             <th>序号</th>

             <th>学号</th>

             <th>姓名</th>

             <th>年龄</th>

         </tr>

         <s:sort comparator="#Mycomparator" source="#request.studentList">

             <s:iterator status="status">

             <tr>

                 <td><s:property value="#status.index+1"/></td>

                 <td><s:property value="id"/></td>

                 <td><s:property value="name"/></td>

                 <td><s:property value="age"/></td>

             </tr>

             </s:iterator>

          </s:sort>

     </table>

Subset 标签：截取标签；

 <%

     List<Student>studentList=new ArrayList<Student>();

     studentList.add(new Student(1,"张三",18));

     studentList.add(new Student(2,"李四",19));

     studentList.add(new Student(5,"王五",25));

     studentList.add(new Student(6,"赵六",28));

     request.setAttribute("studentList", studentList);

 %>

 <body>

     <h1>subset</h1>

     <table border="1">

         <tr>

             <th>序号</th>

             <th>学号</th>

             <th>姓名</th>

             <th>年龄</th>

         </tr>

         <s:subset source="#request.studentList" start="2" count="2">

             <s:iterator status="status">

             <tr>

                 <td><s:property value="#status.index+1"/></td>

                 <td><s:property value="id"/></td>

                 <td><s:property value="name"/></td>

                 <td><s:property value="age"/></td>

             </tr>

             </s:iterator>

         </s:subset>

     </table>

 </body>

四 Strut2 界面标签

Form 标签：表单提交标签；

 <s:form method="post" action="hello" namespace="/forgroud">提交内容</s:form>

Text 标签：文本标签；

 用户名：<s:textfield name="name"></s:textfield>

 密码：<s:password name="password"></s:password>

 备注：<s:textarea name="desc"></s:textarea>

Radios 标签：单选标签；

 性别单选框： <s:radio list="#{0:'男',1:'女' }" name="sex" value="0"></s:radio>

Checkboxlist 标签：复选框标签；

 <s:checkboxlist list="#{0:'唱歌',1:'跳舞',2:'篮球' }"name="hobby" value="1"></s:checkboxlist>

Select 标签：下拉框标签；

 下拉框： <s:select list="#{0:'跳舞',1:'篮球',2:'唱歌' }" name="bobby" value="0"></s:select>