使用Struts的朋友，可能经常发现使用页面的一些标签的时候觉得不够得心应手。比如我们要设计一个用户修改得信息的界面，需要调出一些用户的信息。不幸的是，当页面中含有Checkbox或是radio的时候有没有想过怎么处理？以前我也为这个苦恼，不少论坛上的人也发帖子问这个问题。最近看到了两篇文章，可以解决这个问题。来自IBM developer:
http://www-128.ibm.com/developerworks/java/library/j-sr3.html
http://www-128.ibm.com/developerworks/java/library/j-sr4.html
先调简单的说起吧，我们来实现动态的checkbox:
1、Form的设计：我们这个例子有个String[] mountains，这个变量数组中包含很多的山的名字;还有个数组String[] selectedMountains就是默认选中的一些山，像下面这样很简单。
public class MultiboxForm extends ActionForm {
private String[] selectedMountains = {"Everest","K2","Lhotse","Cho Oyu"};
private String[] mountains ={"Everest","K2","Kangchenjunga","Lhotse","Makalu","Kangchenjunga South","Lhotse Middle","Kangchenjunga West","Lhotse Shar","Cho Oyu"};
public String[] getMountains() {
return mountains;
}
public void setMountains(String[] mountains) {
this.mountains = mountains;
}
public String[] getSelectedMountains() {
return selectedMountains;
}
public void setSelectedMountains(String[] selectedMountains) {
this.selectedMountains = selectedMountains;
}
2、Action的设计：这个就更简单了，一句话，由控制器切换到视图。
return mapping.findForward("success");
3、JSP的设计：
<html:form action="/multibox" name="multiboxForm" type="qiya.deng.struts.form.MultiboxForm">
<logic:iterate name="multiboxForm" property="mountains" id="mountain">
<html:multibox property="selectedMountains">
<bean:write name="mountain"/>
</html:multibox>
<bean:write name="mountain"/><br/>
</logic:iterate>
<br/>
<html:submit/><html:cancel/>
</html:form>
这个相对比较复杂，也是比较中要的。<logic:iterate/>是迭代MultiboxForm中的mountians,
<html:multibox property="selectedMountains">
<bean:write name="mountain"/>
</html:multibox>
这个标签的作用就是selecteDMountains的值和迭代的mountain值一致的时候就会选中。
接下来说Radio，其实Form和Action部分都差不多，只是JSP页面有点不一样，Radio里面甚至牵涉到了JavaScript。
1.From的设计：
private String selectedMountain = "Kangchenjunga West";
private String[] mountains ={"Everest","K2","Kangchenjunga","Lhotse","Makalu","Kangchenjunga South","Lhotse Middle","Kangchenjunga West","Lhotse Shar","Cho Oyu"};
public String[] getMountains() {
return mountains;
}
public void setMountains(String[] mountains) {
this.mountains = mountains;
}
public String getSelectedMountain() {
return selectedMountain;
}
public void setSelectedMountain(String selectedMountain) {
this.selectedMountain = selectedMountain;
}
2.Action同上一样，切换到JSP页面去。
3.重点部分JSP:
<html:form action="/radio" name="radioForm" type="qiya.deng.struts.form.RadioForm">
<bean:define id="selectedRadio" property="selectedMountain" name="radioForm"></bean:define>
<logic:iterate id="mountain" property="mountains" name="radioForm">
<bean:define id="mountainValue">
<bean:write name="mountain"/>
</bean:define>
<html:radio property="selectedMountain" value="<%=mountainValue%>" styleId="<%=mountainValue%>"/>
<bean:write name="mountain"/><br/>
</logic:iterate><br/>
<html:submit/><html:cancel/>
<script type="text/javascript">
<!--
var selectedRadio =
document.forms["radioForm"].elements["<bean:write name="selectedRadio"/>"];
selectedRadio.checked=true;
-->
</script>
</html:form>
"<bean:define/>"定义了一个PageContext作用域的属性selectedRadio，下面的JavaScript的作用就是根据这个属性找到应该选中的Radio。其他的地方和上面那个很相似的。如果还是不太理解先运行，看看生成的HTML代码。