html:options是struts中比较复杂的一个tage lib,用法灵活,但是sturts提供的源码exercise taglib中没有提出常用jsp+actionform这样形式的最直接的总结,现从中总结如下,分两种情况:数组和collection。
需求,要达到:
<select name="beancollectionselect" multiple="multiple" size="10"><option value="value 0">label 0</option><option value="value 1" selected="selected">label 1</option><option value="value 2">label 2</option><option value="value 3" selected="selected">label 3</option><option value="value 4">label 4</option><option value="value 5" selected="selected">label 5</option><option value="value 6">label 6</option><option value="value 7">label 7</option><option value="value 8">label 8</option><option value="value 9">label 9</option></select>
要实现上述效果,需要两步:
第一:设置actionform,
也分两小步:第一小步必须在actionform中,有一句
private collection beancollection;
public collection getbeancollection();
collection beancollection要确保是一个实现,如arraylist,如果不是则会报no collection found的错误,struts的最大不方便就是一旦出问题,定位很难,不知道什么地方使用错误,或忘记设置什么了。
因为前面需求中option的value值和label值不一样,那么在beancollection中保存的就是一个value和label组成的对象,名为labelvaluebean,在labelvaluebean中有两个属性value和label,
在程序某个地方要为beancollection赋值,如:
vector entries = new vector(10); entries.add(new labelvaluebean("label 0", "value 0")); entries.add(new labelvaluebean("label 1", "value 1")); entries.add(new labelvaluebean("label 2", "value 2")); entries.add(new labelvaluebean("label 3", "value 3")); entries.add(new labelvaluebean("label 4", "value 4")); entries.add(new labelvaluebean("label 5", "value 5")); entries.add(new labelvaluebean("label 6", "value 6")); entries.add(new labelvaluebean("label 7", "value 7")); entries.add(new labelvaluebean("label 8", "value 8")); entries.add(new labelvaluebean("label 9", "value 9"));
然后执行setbeancollection(entries);
这样actionform中的beancollection算有值了。
第二小步,需要设置selected,selected有两种,单选和多选:
在actionform中必须有:
private string singleselect = "single 5"; public string getsingleselect() { return (this.singleselect); } public void setsingleselect(string singleselect) { this.singleselect = singleselect; }
或多选,多选必须是数组:
private string[] beancollectionselect = { "value 1", "value 3", "value 5" }; public string[] getbeancollectionselect() { return (this.beancollectionselect); } public void setbeancollectionselect(string beancollectionselect[]) { this.beancollectionselect = beancollectionselect; }
第二:在jsp中写入tang lib语句如下:
<html:select property="beancollectionselect" size="10" multiple="true"> <html:optionscollection name="testbean" property="beancollection"/> </html:select>
其中testbean是actionform的名称。
以上是html:options的collection解决方案,如果option值很少,简单地可以实现为数组,两步:
第一:在actionform中,
private string values[] = { "magazine", "journal", "news paper","other" }; private string labels[] = { "l-magazine", "l-journal", "l-news paper","l-other"}; private string selected = "magazine"; public string getselected(){ return selected; } public void setselected(string selected){ this.selected = selected; } public string[] getvalues(){ return values; } public void setvalues(string[] values){ this.values = values; } public string[] getlabels(){ return values; } public void setlabels(string[] labels){ this.labels = labels; }
第二步在jsp中:
<html:select property="selected" > <html:options name="testbean" property="values" labelproperty="label"/> </html:select>
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