使用Struts的朋友，可能經常發現使用頁面的一些標簽的時候覺得不夠得心應手。比如我們要設計一個用戶修改得信息的界面，需要調出一些用戶的信息。不幸的是，當頁面中含有Checkbox或是radio的時候有沒有想過怎么處理？以前我也為這個苦惱，不少論壇上的人也發帖子問這個問題。最近看到了兩篇文章，可以解決這個問題。來自IBM developer:
http://www-128.ibm.com/developerworks/java/library/j-sr3.html
http://www-128.ibm.com/developerworks/java/library/j-sr4.html
先調簡單的說起吧，我們來實現動態的checkbox:
1、Form的設計：我們這個例子有個String[] mountains，這個變量數組中包含很多的山的名字;還有個數組String[] selectedMountains就是默認選中的一些山，像下面這樣很簡單。
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的設計：這個就更簡單了，一句話，由控制器切換到視圖。
return mapping.findForward("success");
3、JSP的設計：
<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>
這個相對比較復雜，也是比較中要的。<logic:iterate/>是迭代MultiboxForm中的mountians,
<html:multibox property="selectedMountains">
<bean:write name="mountain"/>
</html:multibox>
這個標簽的作用就是selecteDMountains的值和迭代的mountain值一致的時候就會選中。
接下來說Radio，其實Form和Action部分都差不多，只是JSP頁面有點不一樣，Radio里面甚至牽涉到了JavaScript。
1.From的設計：
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同上一樣，切換到JSP頁面去。
3.重點部分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/>"定義了一個PageContext作用域的屬性selectedRadio，下面的JavaScript的作用就是根據這個屬性找到應該選中的Radio。其他的地方和上面那個很相似的。如果還是不太理解先運行，看看生成的HTML代碼。