html:options是Struts中比較復(fù)雜的一個(gè)tage lib，用法靈活，但是Sturts提供的源碼exercise taglib中沒(méi)有提出常用jsp+ActionForm這樣形式的最直接的總結(jié)，現(xiàn)從中總結(jié)如下，分兩種情況：數(shù)組和Collection。
需求，要達(dá)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>
要實(shí)現(xiàn)上述效果，需要兩步：
第一：設(shè)置ActionForm，
也分兩小步：第一小步必須在ActionForm中，有一句
private Collection beanCollection;
public Collection getBeanCollection();
Collection beanCollection要確保是一個(gè)實(shí)現(xiàn)，如ArrayList，如果不是則會(huì)報(bào)No collection found的錯(cuò)誤，Struts的最大不方便就是一旦出問(wèn)題，定位很難，不知道什么地方使用錯(cuò)誤，或忘記設(shè)置什么了。
因?yàn)榍懊嫘枨笾衞ption的value值和label值不一樣，那么在beanCollection中保存的就是一個(gè)value和label組成的對(duì)象，名為L(zhǎng)abelvalueBean，在LabelvalueBean中有兩個(gè)屬性value和label，
在程序某個(gè)地方要為beanCollection賦值，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"));
然后執(zhí)行setBeanCollection(entries);
這樣ActionForm中的beanCollection算有值了。
第二小步，需要設(shè)置Selected，selected有兩種，單選和多選：
在ActionForm中必須有：
private String singleSelect = "Single 5";
public String getSingleSelect()
{
return (this.singleSelect);
}
public void setSingleSelect(String singleSelect)
{
this.singleSelect = singleSelect;
}
或多選，多選必須是數(shù)組：
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中寫入tang lib語(yǔ)句如下：
<html:select property="beanCollectionSelect" size="10" multiple="true">
<html:optionsCollection name="testbean" property="beanCollection"/>
</html:select>
其中testbean是ActionForm的名稱。
以上是html:options的Collection解決方案，如果option值很少，簡(jiǎn)單地可以實(shí)現(xiàn)為數(shù)組，兩步：
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>
Struts標(biāo)簽庫(kù)的使用還是需要小心，不必完全使用Struts的標(biāo)簽庫(kù)，個(gè)人感覺(jué)Struts這種替代Html語(yǔ)句的標(biāo)簽庫(kù)有一種牽強(qiáng)附會(huì)，給使用者掌握帶來(lái)難度，使用者除熟悉html外，還必須理解Struts的對(duì)應(yīng)標(biāo)簽庫(kù)用法，而且這種調(diào)試出錯(cuò)，問(wèn)題也無(wú)法準(zhǔn)確定位，總是抽象地告訴你，no bean 或no form
在Struts中經(jīng)常會(huì)碰到中文轉(zhuǎn)碼的問(wèn)題，最簡(jiǎn)單的辦法就是直接寫一個(gè)ServletFilter
代碼如下：
ChineseFilter.class
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ChineseFilter extends HttpServlet implements Filter {
?private FilterConfig filterConfig;
???? //Handle the passed-in FilterConfig
???? public void init(FilterConfig filterConfig) throws ServletException {
???????? this.filterConfig = filterConfig;
???? }
???? //Process the request/response pair
???? public void doFilter(ServletRequest request, ServletResponse response,
????????????????????????? FilterChain filterChain) {
???????? try {
???????? ?
???????? ?String encoding=filterConfig.getInitParameter("encoding");//從WEB.xml配置文件中取出參數(shù)，這樣我們可以通過(guò)配置修改編碼格式．??????????????????
???????????? request.setCharacterEncoding(encoding);//設(shè)置請(qǐng)求的編碼格式
???????????? filterChain.doFilter(request, response);
???????? } catch (ServletException sx) {
???????????? filterConfig.getServletContext().log(sx.getMessage());
???????? } catch (IOException iox) {
???????????? filterConfig.getServletContext().log(iox.getMessage());
???????? }
???? }
???? //Clean up resources
???? public void destroy() {
???? }
??protected void doGet(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException {
???// TODO Auto-generated method stub
???super.doGet(arg0, arg1);??
??}
??protected void doPost(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException {
???// TODO Auto-generated method stub
???super.doPost(arg0, arg1);???
??}?
}
寫完過(guò)濾器剩下的就是配置Web.xml了
?<filter>
? <filter-name>ChineseFilter</filter-name>
? <filter-class>com.blog.filter.ChineseFilter</filter-class>
<init-param>
??? <param-name>encoding</param-name>
??? <param-value>GBK</param-value> 配置編碼格式，可以配置成你想要的編碼（GBK,bg-2312）
</init-param>
? </filter>
?? <filter-mapping>
??? <filter-name>ChineseFilter</filter-name>
??? <url-pattern>/*</url-pattern>
? </filter-mapping>
好了，簡(jiǎn)單的Filter就完成了．當(dāng)然也有現(xiàn)成的包，比如你用Struts+Spring的話，那Spring中就有現(xiàn)成的轉(zhuǎn)碼過(guò)濾器，我們只要在WEB．xml中配置一下就OK了．
＜filter＞
＜filter-name＞encodingFilter＜/filter-name＞
?＜filter-class＞org.springframework.web.filter.CharacterEncodingFilter＜/filter-class＞
?＜init-param＞
?＜param-name＞encoding＜/param-name＞
. ＜param-value＞GBK＜/param-value＞
?＜/init-param＞
?＜/filter＞
＜filter-mapping＞
?＜filter-name＞encodingFilter＜/filter-name＞
?＜url-pattern＞/*＜/url-pattern＞
?＜/filter-mapping＞