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struts 标签logic:iterate用法详解
<dd>
<div class="Description">核心提示:Iterate主要用来处理在页面上输出集合类,集合一般来说是下列之一: 1、 java对象的数组 2、 ArrayList、Vector、HashMap等 具体用法请参考struts文档,这里不作详细介绍 现在定义一个class,User.java 把它编译成User.class package example; import java.io </div>
</dd>
<dd class="ArticleContent">Iterate主要用来处理在页面上输出集合类,集合一般来说是下列之一: <br><strong>1、 java对象的数组 <br><br>2、 ArrayList、Vector、HashMap等</strong> <br><br>具体用法请参考struts文档,这里不作详细介绍 <br><br>现在定义一个class,User.java 把它编译成User.class <br><br><div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="keyword">package</span><span>example; </span></span> </li>
<li>
<span></span> </li>
<li class="alt">
<span class="keyword">import</span><span>java.io.Serializable; </span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">final</span><span></span><span class="keyword">class</span><span>User</span><span class="keyword">implements</span><span>Serializable{ </span> </li>
<li class="alt">
<span class="keyword">private</span><span>Stringname=</span><span class="keyword">null</span><span>; </span> </li>
<li>
<span class="keyword">private</span><span>Stringpassword=</span><span class="keyword">null</span><span>; </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span>StringgetName(){ </span> </li>
<li class="alt">
<span class="keyword">return</span><span>(</span><span class="keyword">this</span><span>.name); </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">void</span><span>setName(Stringname){ </span> </li>
<li class="alt">
<span class="keyword">this</span><span>.name=name; </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span>StringgetPassword(){ </span> </li>
<li class="alt">
<span class="keyword">return</span><span>(</span><span class="keyword">this</span><span>.password); </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">void</span><span>setPassword(Stringpassword){ </span> </li>
<li class="alt">
<span class="keyword">this</span><span>.password=password; </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>} </span> </li>
</ol></div>
</div>
<br>然后在一个struts webapplication中创建一个jsp,例如iterate.jsp <br><br><div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>%@page</span><span class="attribute">language</span><span>=</span><span class="attribute-value">"java"</span><span>%</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span>%@page</span><span class="attribute">import</span><span>=</span><span class="attribute-value">"example.*"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span class="tag"><</span><span>%@taglib</span><span class="attribute">uri</span><span>=</span><span class="attribute-value">"/WEB-INF/struts-bean.tld"</span><span></span><span class="attribute">prefix</span><span>=</span><span class="attribute-value">"bean"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li>
<span class="tag"><</span><span>%@taglib</span><span class="attribute">uri</span><span>=</span><span class="attribute-value">"/WEB-INF/struts-logic.tld"</span><span></span><span class="attribute">prefix</span><span>=</span><span class="attribute-value">"logic"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span>% </span> </li>
<li class="alt">
<span>java.util.ArrayList</span><span class="attribute">list</span><span>=</span><span class="attribute-value">new</span><span>java.util.ArrayList(); </span> </li>
<li>
<span>User</span><span class="attribute">usera</span><span>=</span><span class="attribute-value">new</span><span>User(); </span> </li>
<li class="alt">
<span>usera.setName("white"); </span> </li>
<li>
<span>usera.setPassword("abcd"); </span> </li>
<li class="alt">
<span>list.add(usera); </span> </li>
<li>
<span>User</span><span class="attribute">userb</span><span>=</span><span class="attribute-value">new</span><span>User(); </span> </li>
<li class="alt">
<span>userb.setName("mary"); </span> </li>
<li>
<span>userb.setPassword("hijk"); </span> </li>
<li class="alt">
<span>list.add(userb); </span> </li>
<li>
<span>session.setAttribute("list",list); </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">html</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">body</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">table</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"100%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"list"</span><span></span><span class="attribute">type</span><span>=</span><span class="attribute-value">"example.User"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">tr</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">td</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"50%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>name:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"name"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">td</span><span class="tag">/></span><span class="tag"><</span><span class="tag-name">td</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"50%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>password:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"password"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">td</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">tr</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">table</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">body</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">html</span><span class="tag">></span><span> </span> </li>
</ol></div>
</div>
<p>将User.class, iterate.jsp放到相应的目录,运行iterate.jsp你就可以看到iterate的效果了 </p>
<p><br><br><strong><span style="font-size: small;">iterate标记</span></strong> <br>id 脚本变量的名称,它保存着集合中当前元素的句柄。 <br>name 代表了你需要叠代的集合,来自session或者request的属性。 <br>type 是其中的集合类元素的类型 <br><br>bean的write标记是用来将属性输出的,name用来匹配iterate的id,property用来匹配相应类的属性<logic:iterate>用法详解22007-04-04 20:34<login:iterate>标记用于在页面中创建一个循环,以此来遍历如数组、Collection、Map这样的对象。该标记的功能强大,在Struts应用的页面中经常使用到。<br><strong>1、对数组进行循环遍历</strong><br> 使用<logic:iterate>标记可以用于遍历数组,以下是一段示例代码:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>String[]</span><span class="attribute">testArray</span><span>={"str1","str2","str3"}; </span> </li>
<li class="alt">
<span>pageContext.setAttribute("test",testArray); </span> </li>
<li>
<span>%</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span class="tag">></span><span> </span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 在上面的代码中,首先定义了一个字符串数组,并为其初始化。接着,将该数组存入pageContext对象中,命名为test1。然后使用<logic:iterate>标记的name属性指定了该数组,并使用id来引用它,同时使用<bean:write>标记来将其显示出来。其结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>str1 </span></span> </li>
<li>
<span>str2 </span> </li>
<li class="alt">
<span>str3</span> </li>
</ol></div>
</div>
<p> 另外,还可以通过length属性来指定输出元素的个数。如下面的代码:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span></span><span class="attribute">length</span><span>=</span><span class="attribute-value">"2"</span><span></span><span class="attribute">offset</span><span>=</span><span class="attribute-value">"1"</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 其中length属性指定了输出元素的个数,offset属性指定了从第几个元素开始输出,如此处为1,则表示从第二个元素开始输出。所以该代码的运行结果应当输出:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>str2 </span></span> </li>
<li>
<span>str3</span> </li>
</ol></div>
</div>
<p> 另外,该标记还有一个indexId属性,它指定一个变量存放当前集合中正被访问的元素的序号,如:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span></span><span class="attribute">length</span><span>=</span><span class="attribute-value">"2"</span><span></span><span class="attribute">offset</span><span>=</span><span class="attribute-value">"1"</span><span></span><span class="attribute">indexId</span><span>=</span><span class="attribute-value">"number"</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"number"</span><span class="tag">/></span><span>:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p>其显示结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="number">1</span><span>:str2 </span></span> </li>
<li>
<span class="number">2</span><span>:str3</span> </li>
</ol></div>
</div>
<p><br><br><strong>2、对HashMap进行循环遍历</strong><br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>HashMap</span><span class="attribute">countries</span><span>=</span><span class="attribute-value">new</span><span>HashMap(); </span> </li>
<li class="alt">
<span>countries.put("country1","中国"); </span> </li>
<li>
<span>countries.put("country2","美国"); </span> </li>
<li class="alt">
<span>countries.put("country3","英国"); </span> </li>
<li>
<span>countries.put("country4","法国"); </span> </li>
<li class="alt">
<span>countries.put("country5","德国"); </span> </li>
<li>
<span>pageContext.setAttribute("countries",countries); </span> </li>
<li class="alt">
<span>%</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"countries"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"key"</span><span class="tag">/></span><span>: </span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"value"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 在bean:write中通过property的key和value分别获得HaspMap对象的键和值。其显示结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>country5:德国 </span></span> </li>
<li>
<span>country3:英国 </span> </li>
<li class="alt">
<span>country2:美国 </span> </li>
<li>
<span>country4:法国 </span> </li>
<li class="alt">
<span>country1:中国</span> </li>
</ol></div>
</div>
<p> 由结果可看出,它并未按添加的顺序将其显示出来。这是因为HaspMap是无序存放的。<br><br><strong>3、嵌套遍历</strong><br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>String[]</span><span class="attribute">colors</span><span>={"red","green","blue"}; </span> </li>
<li class="alt">
<span>String[]</span><span class="attribute">countries1</span><span>={"中国","美国","法国"}; </span> </li>
<li>
<span>String[]</span><span class="attribute">persons</span><span>={"乔丹","布什","克林顿"}; </span> </li>
<li class="alt">
<span>ArrayList</span><span class="attribute">list2</span><span>=</span><span class="attribute-value">new</span><span>ArrayList(); </span> </li>
<li>
<span>list2.add(colors); </span> </li>
<li class="alt">
<span>list2.add(countries1); </span> </li>
<li>
<span>list2.add(persons); </span> </li>
<li class="alt">
<span>pageContext.setAttribute("list2",list2); </span> </li>
<li>
<span>%</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"first"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"list2"</span><span></span><span class="attribute">indexId</span><span>=</span><span class="attribute-value">"numberfirst"</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"numberfirst"</span><span class="tag">/></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"second"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"first"</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"second"</span><span class="tag">/></span><span></span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">br</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 运行效果:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="number">0</span><span>redgreenblue </span></span> </li>
<li>
<span class="number">1</span><span>中国美国法国 </span> </li>
<li class="alt">
<span class="number">2</span><span>乔丹布什克林顿 </span> </li>
</ol></div>
</div>
</dd>
<div class="Description">核心提示:Iterate主要用来处理在页面上输出集合类,集合一般来说是下列之一: 1、 java对象的数组 2、 ArrayList、Vector、HashMap等 具体用法请参考struts文档,这里不作详细介绍 现在定义一个class,User.java 把它编译成User.class package example; import java.io </div>
</dd>
<dd class="ArticleContent">Iterate主要用来处理在页面上输出集合类,集合一般来说是下列之一: <br><strong>1、 java对象的数组 <br><br>2、 ArrayList、Vector、HashMap等</strong> <br><br>具体用法请参考struts文档,这里不作详细介绍 <br><br>现在定义一个class,User.java 把它编译成User.class <br><br><div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="keyword">package</span><span>example; </span></span> </li>
<li>
<span></span> </li>
<li class="alt">
<span class="keyword">import</span><span>java.io.Serializable; </span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">final</span><span></span><span class="keyword">class</span><span>User</span><span class="keyword">implements</span><span>Serializable{ </span> </li>
<li class="alt">
<span class="keyword">private</span><span>Stringname=</span><span class="keyword">null</span><span>; </span> </li>
<li>
<span class="keyword">private</span><span>Stringpassword=</span><span class="keyword">null</span><span>; </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span>StringgetName(){ </span> </li>
<li class="alt">
<span class="keyword">return</span><span>(</span><span class="keyword">this</span><span>.name); </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">void</span><span>setName(Stringname){ </span> </li>
<li class="alt">
<span class="keyword">this</span><span>.name=name; </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span>StringgetPassword(){ </span> </li>
<li class="alt">
<span class="keyword">return</span><span>(</span><span class="keyword">this</span><span>.password); </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="keyword">public</span><span></span><span class="keyword">void</span><span>setPassword(Stringpassword){ </span> </li>
<li class="alt">
<span class="keyword">this</span><span>.password=password; </span> </li>
<li>
<span>} </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>} </span> </li>
</ol></div>
</div>
<br>然后在一个struts webapplication中创建一个jsp,例如iterate.jsp <br><br><div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>%@page</span><span class="attribute">language</span><span>=</span><span class="attribute-value">"java"</span><span>%</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span>%@page</span><span class="attribute">import</span><span>=</span><span class="attribute-value">"example.*"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span class="tag"><</span><span>%@taglib</span><span class="attribute">uri</span><span>=</span><span class="attribute-value">"/WEB-INF/struts-bean.tld"</span><span></span><span class="attribute">prefix</span><span>=</span><span class="attribute-value">"bean"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li>
<span class="tag"><</span><span>%@taglib</span><span class="attribute">uri</span><span>=</span><span class="attribute-value">"/WEB-INF/struts-logic.tld"</span><span></span><span class="attribute">prefix</span><span>=</span><span class="attribute-value">"logic"</span><span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span>% </span> </li>
<li class="alt">
<span>java.util.ArrayList</span><span class="attribute">list</span><span>=</span><span class="attribute-value">new</span><span>java.util.ArrayList(); </span> </li>
<li>
<span>User</span><span class="attribute">usera</span><span>=</span><span class="attribute-value">new</span><span>User(); </span> </li>
<li class="alt">
<span>usera.setName("white"); </span> </li>
<li>
<span>usera.setPassword("abcd"); </span> </li>
<li class="alt">
<span>list.add(usera); </span> </li>
<li>
<span>User</span><span class="attribute">userb</span><span>=</span><span class="attribute-value">new</span><span>User(); </span> </li>
<li class="alt">
<span>userb.setName("mary"); </span> </li>
<li>
<span>userb.setPassword("hijk"); </span> </li>
<li class="alt">
<span>list.add(userb); </span> </li>
<li>
<span>session.setAttribute("list",list); </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>%</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">html</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">body</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">table</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"100%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"list"</span><span></span><span class="attribute">type</span><span>=</span><span class="attribute-value">"example.User"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">tr</span><span class="tag">></span><span class="tag"><</span><span class="tag-name">td</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"50%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>name:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"name"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">td</span><span class="tag">/></span><span class="tag"><</span><span class="tag-name">td</span><span></span><span class="attribute">width</span><span>=</span><span class="attribute-value">"50%"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span>password:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"a"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"password"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">td</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">tr</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span></span> </li>
<li>
<span class="tag"></</span><span class="tag-name">table</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">body</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">html</span><span class="tag">></span><span> </span> </li>
</ol></div>
</div>
<p>将User.class, iterate.jsp放到相应的目录,运行iterate.jsp你就可以看到iterate的效果了 </p>
<p><br><br><strong><span style="font-size: small;">iterate标记</span></strong> <br>id 脚本变量的名称,它保存着集合中当前元素的句柄。 <br>name 代表了你需要叠代的集合,来自session或者request的属性。 <br>type 是其中的集合类元素的类型 <br><br>bean的write标记是用来将属性输出的,name用来匹配iterate的id,property用来匹配相应类的属性<logic:iterate>用法详解22007-04-04 20:34<login:iterate>标记用于在页面中创建一个循环,以此来遍历如数组、Collection、Map这样的对象。该标记的功能强大,在Struts应用的页面中经常使用到。<br><strong>1、对数组进行循环遍历</strong><br> 使用<logic:iterate>标记可以用于遍历数组,以下是一段示例代码:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>String[]</span><span class="attribute">testArray</span><span>={"str1","str2","str3"}; </span> </li>
<li class="alt">
<span>pageContext.setAttribute("test",testArray); </span> </li>
<li>
<span>%</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span class="tag">></span><span> </span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 在上面的代码中,首先定义了一个字符串数组,并为其初始化。接着,将该数组存入pageContext对象中,命名为test1。然后使用<logic:iterate>标记的name属性指定了该数组,并使用id来引用它,同时使用<bean:write>标记来将其显示出来。其结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>str1 </span></span> </li>
<li>
<span>str2 </span> </li>
<li class="alt">
<span>str3</span> </li>
</ol></div>
</div>
<p> 另外,还可以通过length属性来指定输出元素的个数。如下面的代码:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span></span><span class="attribute">length</span><span>=</span><span class="attribute-value">"2"</span><span></span><span class="attribute">offset</span><span>=</span><span class="attribute-value">"1"</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 其中length属性指定了输出元素的个数,offset属性指定了从第几个元素开始输出,如此处为1,则表示从第二个元素开始输出。所以该代码的运行结果应当输出:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>str2 </span></span> </li>
<li>
<span>str3</span> </li>
</ol></div>
</div>
<p> 另外,该标记还有一个indexId属性,它指定一个变量存放当前集合中正被访问的元素的序号,如:<br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"show"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"test"</span><span></span><span class="attribute">length</span><span>=</span><span class="attribute-value">"2"</span><span></span><span class="attribute">offset</span><span>=</span><span class="attribute-value">"1"</span><span></span><span class="attribute">indexId</span><span>=</span><span class="attribute-value">"number"</span><span class="tag">></span><span> </span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"number"</span><span class="tag">/></span><span>:</span><span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"show"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p>其显示结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="number">1</span><span>:str2 </span></span> </li>
<li>
<span class="number">2</span><span>:str3</span> </li>
</ol></div>
</div>
<p><br><br><strong>2、对HashMap进行循环遍历</strong><br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>HashMap</span><span class="attribute">countries</span><span>=</span><span class="attribute-value">new</span><span>HashMap(); </span> </li>
<li class="alt">
<span>countries.put("country1","中国"); </span> </li>
<li>
<span>countries.put("country2","美国"); </span> </li>
<li class="alt">
<span>countries.put("country3","英国"); </span> </li>
<li>
<span>countries.put("country4","法国"); </span> </li>
<li class="alt">
<span>countries.put("country5","德国"); </span> </li>
<li>
<span>pageContext.setAttribute("countries",countries); </span> </li>
<li class="alt">
<span>%</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"countries"</span><span class="tag">></span><span> </span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"key"</span><span class="tag">/></span><span>: </span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"country"</span><span></span><span class="attribute">property</span><span>=</span><span class="attribute-value">"value"</span><span class="tag">/></span><span> </span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 在bean:write中通过property的key和value分别获得HaspMap对象的键和值。其显示结果为:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span>country5:德国 </span></span> </li>
<li>
<span>country3:英国 </span> </li>
<li class="alt">
<span>country2:美国 </span> </li>
<li>
<span>country4:法国 </span> </li>
<li class="alt">
<span>country1:中国</span> </li>
</ol></div>
</div>
<p> 由结果可看出,它并未按添加的顺序将其显示出来。这是因为HaspMap是无序存放的。<br><br><strong>3、嵌套遍历</strong><br>程序代码</p>
<div>
<div class="dp-highlighter"><ol class="dp-xml">
<li class="alt">
<span><span class="tag"><</span><span>% </span></span> </li>
<li>
<span>String[]</span><span class="attribute">colors</span><span>={"red","green","blue"}; </span> </li>
<li class="alt">
<span>String[]</span><span class="attribute">countries1</span><span>={"中国","美国","法国"}; </span> </li>
<li>
<span>String[]</span><span class="attribute">persons</span><span>={"乔丹","布什","克林顿"}; </span> </li>
<li class="alt">
<span>ArrayList</span><span class="attribute">list2</span><span>=</span><span class="attribute-value">new</span><span>ArrayList(); </span> </li>
<li>
<span>list2.add(colors); </span> </li>
<li class="alt">
<span>list2.add(countries1); </span> </li>
<li>
<span>list2.add(persons); </span> </li>
<li class="alt">
<span>pageContext.setAttribute("list2",list2); </span> </li>
<li>
<span>%</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"first"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"list2"</span><span></span><span class="attribute">indexId</span><span>=</span><span class="attribute-value">"numberfirst"</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"numberfirst"</span><span class="tag">/></span><span></span> </li>
<li class="alt">
<span class="tag"><</span><span class="tag-name">logic:iterate</span><span></span><span class="attribute">id</span><span>=</span><span class="attribute-value">"second"</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"first"</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">bean:write</span><span></span><span class="attribute">name</span><span>=</span><span class="attribute-value">"second"</span><span class="tag">/></span><span></span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
<li>
<span class="tag"><</span><span class="tag-name">br</span><span class="tag">></span><span></span> </li>
<li class="alt">
<span class="tag"></</span><span class="tag-name">logic:iterate</span><span class="tag">></span><span></span> </li>
</ol></div>
</div>
<p> 运行效果:</p>
<div>
<div class="dp-highlighter"><ol class="dp-j">
<li class="alt">
<span><span class="number">0</span><span>redgreenblue </span></span> </li>
<li>
<span class="number">1</span><span>中国美国法国 </span> </li>
<li class="alt">
<span class="number">2</span><span>乔丹布什克林顿 </span> </li>
</ol></div>
</div>
</dd>
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