1 <?xml version="1.0" encoding="UTF-8"?>   2     <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">   3     <taglib>     <!-- 自定义库标签的根 -->   4     <tlibversion>1.2</tlibversion>     <!-- 版本号 -->   5     <jspversion>1.1</jspversion>       <!-- JSP版本号 -->   6     <shortname>stu</shortname>        <!-- prefix="stu"标签名称-->   7     <uri>StudentTags</uri>   <!-- uri="StudentTags" 外界导入标签时，认识的名字，很重要。-->   8        9     <tag>  10      <name>selectAll</name>                            <!-- 标签名称 -->  11      <tagclass>com.bjsxt.sxf.tag.SeclectAllSt</tagclass>          <!-- 对应的java类的全路径 -->  12     </tag>  13       14     <!-- 有属性的标签，可以有多个属性  <attribute>并列 -->  15       <tag>  16            <name>selectBySex</name>  <!-- 标签名称 -->17             <tagclass>com.bjsxt.sxf.tag.SeclectStBySex</tagclass> 18             <attribute>   <!-- 对应标签的属性。 -->  19                  <name>sex</name>  20                  <required>true</required>  <!-- 是必需写的属性，即没有写属性标签不能被正常使用 -->  21             </attribute>         22        </tag>  23       <!-- 按班级学生id查询出班级集合，存放到属性var指定的变量中，然后利用s标签的迭代标签，将var指定的变量存放的学生集合遍历出来 -->24        <tag>25                <name>selectByClassId</name> <!-- 标签名称 --> 26                <tagclass>com.bjsxt.sxf.tag.MyTag</tagclass> <!-- 对应的java类的全路径 -->  27                <body-content>JSP</body-content><!-- 如果不需要标签体则设置empty，反之设定jsp，内部可以运行jsp所有的语法 -->28                <attribute>29                    <name>classId</name><!--指定属性名 和标签java类一致-->30                    <required>true</required><!--该属性是否是必须，如果非必须没设置则为空。 -->31                    <rtexprvalue>true</rtexprvalue><!-- 该属性能不能动态使用表达式为该属性赋值 true可以  false不可以  使用脚本和EL表达式来获取动态的值 -->32                </attribute>33                <attribute>34                    <name>var</name>35                    <required>true</required>36                    <rtexprvalue>false</rtexprvalue>37                </attribute>38                <attribute>39                    <name>num</name>40                    <required>false</required>41                    <rtexprvalue>false</rtexprvalue>42                </attribute>43        </tag>44        <!-- 自定义的myif标签 -->45        <tag>46                <name>myif</name>47                <tagclass>com.bjsxt.sxf.tag.MyIfTag</tagclass>48                <bodycontent>JSP</bodycontent>49                <attribute>50                    <name>flag</name>51                    <required>true</required>52                    <rtexprvalue>true</rtexprvalue>53                </attribute>54                <attribute>55                    <name>condition</name>56                    <required>true</required>57                    <rtexprvalue>true</rtexprvalue>58                </attribute>59        </tag>60        <!-- 自定义的myelseif标签 -->61         <tag>62                <name>myelseif</name>63                <tagclass>com.bjsxt.sxf.tag.MyElseIfTag</tagclass>64                <bodycontent>JSP</bodycontent>65                <attribute>66                    <name>flag</name>67                    <required>true</required>68                    <rtexprvalue>true</rtexprvalue>69                </attribute>70                <attribute>71                    <name>condition</name>72                    <required>true</required>73                    <rtexprvalue>true</rtexprvalue>74                </attribute>75        </tag>76        <!-- 自定义的myelse标签 -->77        <tag>78                <name>myelse</name>79                <tagclass>com.bjsxt.sxf.tag.MyElseTag</tagclass>80                <bodycontent>JSP</bodycontent>81        </tag>82        83     </taglib>  

  1 package com.bjsxt.sxf.tag;  2   3 import javax.servlet.http.HttpServletRequest;  4 import javax.servlet.http.HttpServletResponse;  5   6 import org.apache.struts2.components.Component;  7 import org.apache.struts2.views.jsp.ComponentTagSupport;  8   9 import com.bjsxt.sxf.tag.compant.MyIfComponent; 10 import com.opensymphony.xwork2.util.ValueStack; 11 /** 12  * myif的标签类  13 * @ClassName: MyIfTag  14 * @Description: TODO(这里用一句话描述这个类的作用)  15 * @author 尚晓飞 16 * @date 2014-10-22 下午3:46:45  17 * 18  */ 19 public class MyIfTag extends ComponentTagSupport { 20     private String flag;//if判断的标示 21     private String condition;//可以传递的多个参数代表 22      23     //生成标签逻辑类的对象。多态。父类引用，指向子类对象 24     @Override 25     public Component getBean(ValueStack arg0, HttpServletRequest arg1, 26             HttpServletResponse arg2) {     27         return new MyIfComponent(arg0, arg1,arg2); 28     } 29      30     //给逻辑类的属性赋值 31     @Override 32     protected void populateParams() { 33         super.populateParams(); 34         MyIfComponent myIfComponent=(MyIfComponent) getComponent(); 35         myIfComponent.setFlag(flag); 36         myIfComponent.setCondition(condition); 37     } 38  39     public String getFlag() { 40         return flag; 41     } 42  43     public void setFlag(String flag) { 44         this.flag = flag; 45     } 46  47     public String getCondition() { 48         return condition; 49     } 50  51     public void setCondition(String condition) { 52         this.condition = condition; 53     } 54  55      56 } 57  58  59 package com.bjsxt.sxf.tag; 60  61 import javax.servlet.http.HttpServletRequest; 62 import javax.servlet.http.HttpServletResponse; 63  64 import org.apache.struts2.components.Component; 65 import org.apache.struts2.views.jsp.ComponentTagSupport; 66  67 import com.bjsxt.sxf.tag.compant.MyElseIfComponent; 68 import com.opensymphony.xwork2.util.ValueStack; 69 /** 70  * myelseif的标签类 71 * @ClassName: MyElseIfTag  72 * @Description: TODO(这里用一句话描述这个类的作用)  73 * @author 尚晓飞 74 * @date 2014-10-22 下午3:47:59  75 * 76  */ 77 public class MyElseIfTag extends ComponentTagSupport{ 78     private String flag;//elsif判断的标示 79     private String condition;//可以传递的多个参数代表 80      81      82     //返回该标签逻辑类的对象 83     @Override 84     public Component getBean(ValueStack arg0, HttpServletRequest arg1, 85             HttpServletResponse arg2) { 86          87         return new MyElseIfComponent(arg0, arg1, arg2); 88     } 89      90     //给该标签逻辑类对象赋值 91     @Override 92     protected void populateParams() { 93         super.populateParams(); 94         MyElseIfComponent myElseIfComponent=(MyElseIfComponent) getComponent(); 95         myElseIfComponent.setFlag(flag); 96         myElseIfComponent.setCondition(condition); 97     } 98     public String getFlag() { 99         return flag;100     }101     public void setFlag(String flag) {102         this.flag = flag;103     }104     public String getCondition() {105         return condition;106     }107     public void setCondition(String condition) {108         this.condition = condition;109     }110     111 112 }113 114 115 package com.bjsxt.sxf.tag;116 117 import javax.servlet.http.HttpServletRequest;118 import javax.servlet.http.HttpServletResponse;119 120 import org.apache.struts2.components.Component;121 import org.apache.struts2.views.jsp.ComponentTagSupport;122 123 import com.bjsxt.sxf.tag.compant.MyElseComponent;124 import com.opensymphony.xwork2.util.ValueStack;125 /**126  * 自定义的else标签127 * @ClassName: MyElse 128 * @Description: TODO(这里用一句话描述这个类的作用) 129 * @author 尚晓飞130 * @date 2014-10-22 下午2:24:30 131 *132  */133 public class MyElseTag extends ComponentTagSupport{134 135     @Override136     public Component getBean(ValueStack arg0, HttpServletRequest arg1,137             HttpServletResponse arg2) {138         // TODO Auto-generated method stub139         return new MyElseComponent(arg0, arg1, arg2);140     }141 142     @Override143     protected void populateParams() {144         // TODO Auto-generated method stub145         super.populateParams();146     }147 148     149 }

  1 package com.bjsxt.sxf.tag.compant;  2   3 import java.io.Writer;  4   5 import javax.servlet.http.HttpServletRequest;  6 import javax.servlet.http.HttpServletResponse;  7   8 import org.apache.struts2.components.Component;  9  10 import com.opensymphony.xwork2.util.ValueStack; 11  12 /** 13  * myif标签逻辑类 没有@的标签注解，好像不影响， 14 * @ClassName: MyIfComponent  15 * @Description: TODO(这里用一句话描述这个类的作用)  16 * @author 尚晓飞 17 * @date 2014-10-22 下午3:49:40  18 * 19  */ 20 public class MyIfComponent extends Component { 21     protected String flag; 22     protected String condition; 23     public static final String MyANSWER = "struts.if.answer"; 24     protected Boolean answer; 25      26      27     public MyIfComponent(ValueStack stack,HttpServletRequest req,HttpServletResponse resp) { 28         super(stack); 29     } 30  31  32     //标签运行开始执行 33     @Override 34     public boolean start(Writer writer) { 35         answer = (Boolean) findValue(flag, Boolean.class); 36         if (answer == null) { 37                 answer = Boolean.FALSE; 38             } 39          40         stack.getContext().put(MyANSWER, answer); 41         boolean flg=answer.booleanValue(); 42         return flg; 43     } 44  45     //标签运行结束执行 46     @Override 47     public boolean end(Writer writer, String body) { 48         stack.getContext().put(MyANSWER, answer); 49         boolean fd=super.end(writer, body); 50         return fd; 51     } 52     public String getFlag() { 53         return flag; 54     } 55  56     public void setFlag(String flag) { 57         this.flag = flag; 58     } 59  60     public String getCondition() { 61         return condition; 62     } 63  64     public void setCondition(String condition) { 65         this.condition = condition; 66     } 67  68      69 } 70  71  72 package com.bjsxt.sxf.tag.compant; 73  74 import java.io.Writer; 75 import java.util.Map; 76  77 import javax.servlet.http.HttpServletRequest; 78 import javax.servlet.http.HttpServletResponse; 79  80 import org.apache.struts2.components.Component; 81  82 import com.opensymphony.xwork2.util.ValueStack; 83  84 /** 85  * myelseif的逻辑类 86 * @ClassName: MyElseIfComponent  87 * @Description: TODO(这里用一句话描述这个类的作用)  88 * @author 尚晓飞 89 * @date 2014-10-22 下午3:50:49  90 * 91  */ 92 public class MyElseIfComponent extends Component { 93     protected String flag; 94     protected String condition; 95     public static final String MyANSWER = "struts.myelseif.answer"; 96     protected Boolean answer; 97  98     public MyElseIfComponent(ValueStack stack,HttpServletRequest req,HttpServletResponse resp) { 99         super(stack);100         // TODO Auto-generated constructor stub101     }102     103     104     @Override105     public boolean start(Writer writer) {106         boolean myflag=false;107         //获取值栈108          Map context = stack.getContext();109         //先从值栈中获取if标签的flag的值110          Boolean ifResult = (Boolean) context.get(MyIfComponent.MyANSWER);111         //如果存在elseif 则需要获取该值112          Boolean elseIfResult=(Boolean) context.get(MyElseIfComponent.MyANSWER);113          context.remove(MyIfComponent.MyANSWER);114          context.remove(MyElseIfComponent.MyANSWER);115         116         //判断是否存在if=true的情况117         if(ifResult!=null&&ifResult==true){118             //if=true119              myflag=false;120         }else{121             //if=false122             //是否存在else if123             if(elseIfResult!=null&&elseIfResult==true){124                 //else if=true;125                 myflag=false;126             }else{127                 //else if=false或者不存在上个else if128                 answer = (Boolean) findValue(flag, Boolean.class);129                 if (answer == null) {130                     answer = Boolean.FALSE;131                 }132                 stack.getContext().put(MyANSWER, answer);133                 myflag=answer.booleanValue();134             }135         }136         return myflag;137     }138     @Override139     public boolean end(Writer writer, String body) {140         stack.getContext().put(MyANSWER, answer);141         return super.end(writer, body);142     }143     public String getFlag() {144         return flag;145     }146     public void setFlag(String flag) {147         this.flag = flag;148     }149     public String getCondition() {150         return condition;151     }152     public void setCondition(String condition) {153         this.condition = condition;154     }155     public Boolean getAnswer() {156         return answer;157     }158     public void setAnswer(Boolean answer) {159         this.answer = answer;160     }161     162     163 }164 165 166 package com.bjsxt.sxf.tag.compant;167 168 import java.io.Writer;169 import java.util.Map;170 171 import javax.servlet.http.HttpServletRequest;172 import javax.servlet.http.HttpServletResponse;173 174 import org.apache.struts2.components.Component;175 176 import com.opensymphony.xwork2.util.ValueStack;177 178 public class MyElseComponent extends Component{179     180     /**181      * myelse的逻辑类182      * 183      * @Title: EncodingRequestWrapper 184      * @Description: 构造函数185      * @param stack186      * @param req187      * @param response188      * @author 尚晓飞189      * @date 2014-10-22 下午3:51:24190      */191     public MyElseComponent(ValueStack stack,HttpServletRequest req,HttpServletResponse response) {192         super(stack);193     }194     //Myelse标签运行开始195     @Override196     public boolean start(Writer writer) {197         boolean myflg=false;198         //获取值栈199          Map context = stack.getContext();200          //获取if的值201          Boolean ifResult = (Boolean) context.get(MyIfComponent.MyANSWER);202          //获取else的值203          Boolean elseifResult=(Boolean) context.get(MyElseIfComponent.MyANSWER);204          //移除值栈中的值205          context.remove(MyIfComponent.MyANSWER);206          context.remove(MyElseIfComponent.MyANSWER);207          208          //判断是否存在if209          if(ifResult!=null&&ifResult==true){210              //存在if，并且为true;211              myflg=false;212          }else{213              //if为false214              //判断elseif是否存在215              if(elseifResult!=null&&elseifResult==true){216                  //存在elseif标签,且==true217                  myflg=false;218              }else{219                  //不存在elseif标签或者为elseif标签==false或者if标签为false220                  myflg=true;221              }222          }223 224         225          return myflg;226     }227     228     @Override229     public boolean end(Writer writer, String body) {230         // TODO Auto-generated method stub231         boolean d=super.end(writer, body);232         return d;233     }234 235 236 237     238 }

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <%@ taglib uri="StudentTags" prefix="stu" %> 3 <%@ taglib uri="/struts-tags" prefix="s"%> 4 <% 5 String path = request.getContextPath(); 6 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 7 %> 8  9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">10 <html>11   <head>12   </head>13   14   <body>15     This is my JSP page. <br>16     <a href="<%=request.getContextPath()%>/StudentAction!reportStudent.action">班级表单下载</a>17     <h1>查询出所有学生的标签效果</h1>18        <stu:selectAll></stu:selectAll>19        <h1>查询出指定性别的学生的标签效果</h1>20        <stu:selectBySex sex="男"></stu:selectBySex>21        <h1>查询出指定班级id的学生集合的标签效果</h1>22        <stu:selectByClassId var="students" classId="1" >23            <table border="2">24                <tr>25                    <td>id</td>26                    <td>姓名</td>27                    <td>性别</td>28                    <td>班级</td>29                </tr>30                <s:iterator value="#students" var="stu">31                    <tr>32                        <td><s:property value="#stu.id"/></td>33                        <td><s:property value="#stu.name"/></td>34                        <td><s:property value="#stu.sex"/></td>35                        <td><s:property value="#stu.classRoom.name"/></td>36                    </tr>37                </s:iterator>38            </table>39        </stu:selectByClassId>40        41        <h1>我是中国人</h1>42        <stu:myif flag="1==3" condition="shangxiaofei">43            <h1>myif是true</h1>44        </stu:myif>45        <stu:myelseif flag="1==2" condition="first">46            <h1>第一个myelseif是false</h1>47        </stu:myelseif>48        <stu:myelseif flag="1==1" condition="sencod">49            <h1>第二个myelseif是true</h1>50        </stu:myelseif>51        <stu:myelse>52            <h1>false</h1>53        </stu:myelse>54   </body>55   56 </html>