项目里用到了一个多选下拉框，懒得在网上找，自己试着写了个简单的先用着，贴出来给学习的童鞋参考下。
这段JS控制各种事件（multiSelect.js）
/**
* created by yuandong
* created date 2012-5-23
* last updated date 2012-6-8
*/
jQuery(document).ready(function()
{
//Click event of select div
$('.multiSelectDiv').click(function(e){
var text = $(this).find('input[type=text]');
var hidden = $(this).find('input[type=hidden]');
var target = $(e.target);
//If target is text
if(target.attr('type') == text.attr('type'))
{
//Hide other div
$('.multiSelectDiv').find('div').each(function(){
$(this).animate({opacity: 'hide'}, 300);
});
var div = $(this).find('div');
var offSet = text.offset();
var left = offSet.left;
var top = offSet.top;
if(div.is(":visible"))
{
div.animate({opacity: 'hide'}, 300);
}
else
{
div.css({"top":top+20,"left":left}).animate({opacity:'show'}, 300);
}
}
//If target is checkbox
else if(target.attr('type') == 'checkbox')
{
var textVal = '';
var hiddenVal = '';
var selectDivObj = $(this);
var curCheckboxCount = 0;
var selectedCheckboxCount = 0;
//Get value by selected checkbox
$(this).find('input[type=checkbox][class!=selectAll]').each(function(){
if($(this).is(':checked'))
{
textVal += $(this).parent().parent().find('span').text() + ',';
hiddenVal += $(this).val() + ',';
selectedCheckboxCount++;
}
//When exist checkbox not select,set 'select all' to not select
else
{
selectDivObj.find('input[type=checkbox][class=selectAll]').attr('checked','');
}
curCheckboxCount++;
});
if(curCheckboxCount>0 && selectedCheckboxCount>0 && curCheckboxCount==selectedCheckboxCount)
{
selectDivObj.find('input[type=checkbox][class=selectAll]').attr('checked','true');
}
text.val(textVal.substring(0,textVal.length-1));
hidden.val(hiddenVal.substring(0,hiddenVal.length-1));
}
//If target is clearImg, clear text,hidden,and checkbox value
else if($(this).find('img').length>0 && target.attr('name') == 'clearImg')
{
text.val('');
hidden.val('');
$(this).find('input[type=checkbox]').each(function(){
if($(this).is(":checked"))
{
$(this).attr("checked",'');
}
});
}
//If target is selectImg, show select
else if($(this).find('img').length>0 && target.attr('name') == 'selectImg')
{
text.click();
}
});
//Hide div when user click other area
$('html').click(function(e){
//If not multi select div area, return
if($(e.target).isChildAndSelfOf (".multiSelectDiv"))
{
return;
}
//Else hide select div
else
{
$('.multiSelectDiv').find('div').each(function(){
$(this).animate({opacity: 'hide'}, 300);
});
}
});
//Select all items
$('.selectAll').click(function(e){
var all = $(this);
all.parent().parent().parent().find('input[type=checkbox]').each(function(){
if(all.is(":checked"))
{
$(this).attr("checked",'true');
}
else
{
$(this).attr("checked",'');
}
});
});
//Check current elements
jQuery.fn.isChildAndSelfOf = function(b){
return (this.closest(b).length > 0);
};
//On init
initMultiSelect();
});
//Init select
function initMultiSelect()
{
$('.multiSelectDiv').each(function(){
var hiddenVal = $(this).find('input[type=hidden]').val();
var textVal = '';
var curCheckboxCount = 0;
var selectedCheckboxCount = 0;
var selectDivObj = $(this);
//Select checkBox and set up input value after do query
if(hiddenVal != '')
{
$(this).find('input[type=checkbox][class!=selectAll]').each(function(){
if(hiddenVal.indexOf($(this).val()) != -1)
{
$(this).attr('checked',true);
textVal += $(this).parent().parent().find('span').text() + ',';
selectedCheckboxCount ++;
}
curCheckboxCount ++;
});
$(this).find('input[type=text]').val(textVal.substring(0,textVal.length-1));
//If checkbox count of current select is equals selected checkbox count,checked 'select all'
if(curCheckboxCount>0 && selectedCheckboxCount>0 && curCheckboxCount==selectedCheckboxCount)
{
selectDivObj.find('input[type=checkbox][class=selectAll]').attr('checked','true');
}
}
//Set up the width of the select div
var textWidth = 0;
var img1Width = 0;
var img2Width = 0;
var textObj = $(this).find('input[type=text]');
textWidth = textObj.width();
var img1Obj = $(this).find('img');
var tempImgObj = new Image();
tempImgObj.src = img1Obj.attr( 'src');
img1Width = tempImgObj.width;
var img2Obj = img1Obj.next('img');
tempImgObj.src = img2Obj.attr( 'src');
img2Width = tempImgObj.width;
$(this).width(textWidth + img1Width + img2Width + 10);
});
}标签类：
public class MultiSelectTaglib extends TagSupport
{
//下拉框数据,初始化下拉框的数据
private List<LabelValueBean> items;
//名称参数,传到后台的名称
private String nameParams;
//id参数，传到后台的id
private String idParams;
//当前id的值，主要用于查询后再次选中查询前的checkbox
private String curIdVal;
//样式，设置文本框样式
private String textStyle;
//是否只读(可选)，设置文本框只读属性，默认只读
private boolean readonly = true;
//是否需要放大镜(可选)，设置是否有放大镜图标，默认有放大镜图标
private boolean hasSelectImg = true;
//是否需要清空图标(可选)，设置是否有清空图标，默认有清空图标
private boolean hasClearImg = true;
//下拉框高度(可选)，设置高度后，超过高度后会显示下拉框
private String selectHeight;
//下拉框宽度(可选)，设置宽度后，超过高度后会显示下拉框,默认200px
private String selectWidth;
//是否需要全选功能(可选)
private boolean hasAllSelector;
//国际化用到的参数
private final String SELECT_ALL = "select_all";
private final String RESOURCE_NAME = "ssb_application_resource";
/**
* 重写doStartTag
*/
public int doStartTag()
{
//得到资源文件
Locale locale = pageContext.getRequest().getLocale();
ResourceBundle bundle = ResourceBundle.getBundle(RESOURCE_NAME, locale);
Map<String, String> messages = new HashMap<String, String>();
messages.put(SELECT_ALL, bundle.getString("multiSelect.selectAll"));
JspWriter out = pageContext.getOut();
if (out != null)
{
try
{
out.print(getContentString(messages));
} catch (IOException e)
{
PPMLog.debug("多选下拉框标签异常: " + e.getMessage());
}
}
return SKIP_BODY;
}
/**
* 拼接显示的多选框域
* @return
*/
private String getContentString(Map<String, String> messages)
{
//用户存放HTML内容串
StringBuffer contentStr = new StringBuffer() ;
//如果没设置宽度，默认200px
if(StringHelper.isEmpty(selectWidth))
{
selectWidth = "200px";
}
//contentStr.append("<div class=\"multiSelectDiv\" style=\"width:" + selectWidth + "\">")
contentStr.append("<div class=\"multiSelectDiv\">")
.append("<input type=\"text\" name=\"").append(nameParams).append("\"");
//如果需要把文本框设置为只读
if(readonly)
{
contentStr.append("readonly=\"readonly\"");
}
//文本框默认样式
String textDefStyle = "width:200px";
contentStr.append(" style=\"").append(StringHelper.isEmpty(textStyle) ? textDefStyle : textStyle).append("\"/>")
.append("<input type=\"hidden\" name=\"").append(idParams).append("\" value=\"" + curIdVal + "\"/>");
HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
if(hasSelectImg)
{
String imgPath = request.getContextPath() + "/images/projectinfo/search.gif";
contentStr.append("<img src=\"" + imgPath + "\" class=\"icon\" style=\"cursor:pointer\" name=\"selectImg\"/>");
}
//如果需要清除图标
if(hasClearImg)
{
String imgPath = request.getContextPath() + "/images/clear.gif";
contentStr.append("<img src=\"" + imgPath + "\" class=\"icon\" style=\"cursor:pointer\" name=\"clearImg\"/>");
}
/*
* 如果以后要支持自定义其他样式，可以将这里的高度和宽度去掉， 直接自定义下拉框的样式，
* 注意这里默认的"display:none;position: absolute;"是必需的样式，如果自定义里有同样属性定义，会直接覆盖同名属性的值.
* 这里为了使用简便，暂时不支持
String selectDefStyle = "display:none;position: absolute;";
contentStr.append(" style=\"").append(StringHelper.isEmpty(selectStyle) ? selectDefStyle+selectStyle : selectStyle).append("\"/>");
*/
contentStr.append("<div style=\"display:none;position: absolute;");
//如果设置了下拉框高度
if(StringHelper.isNotEmpty(selectHeight))
{
contentStr.append("overflow:auto;height:" + selectHeight + ";");
}
contentStr.append("width:" + selectWidth + ";");
contentStr.append("\">");
contentStr.append(" <table cellspacing=\"1\" class=\"tb_datalist\">");
//如果list不为空，生成下拉列表
if(items.isEmpty())
{
contentStr.append("<tr><td><td></tr>");
}
else
{
//如果需要全选功能
if(hasAllSelector)
{
contentStr.append("<tr class=\"tr_title\">");
contentStr.append("<td width=\"10%\">")
.append(" <input class=\"selectAll\" value=\"\" type=\"checkbox\"/></td>");
contentStr.append("<td width=\"90%\"><span>").append(messages.get(SELECT_ALL)).append("</span></td>");
contentStr.append("</tr>");
}
//生成下拉列表
for(LabelValueBean labelVal:items)
{
if(labelVal != null)
{
contentStr.append("<tr>");
contentStr.append("<td width=\"10%\">")
.append(" <input type=\"checkbox\" value=\"" + labelVal .getValue()+ "\"/></td>");
contentStr.append("<td width=\"90%\">").append("<span>" + labelVal.getLabel() + "</span></td>");
contentStr.append("</tr>");
}
}
}
contentStr.append("</table>");
contentStr.append("</div>");
contentStr.append("</div>");
return contentStr.toString() ;
}
public void release() {
super.release();
}
public void setNameParams(String nameParams)
{
this.nameParams = nameParams;
}
public void setStyle(String textStyle)
{
this.textStyle = textStyle;
}
public void setIdParams(String idParams)
{
this.idParams = idParams;
}
public void setCurIdVal(String curIdVal)
{
this.curIdVal = curIdVal;
}
public void setItems(List<LabelValueBean> items)
{
this.items = items;
}
public void setHasClearImg(Boolean hasClearImg)
{
this.hasClearImg = hasClearImg;
}
public void setSelectWidth(String selectWidth)
{
this.selectWidth = selectWidth;
}
public void setSelectHeight(String selectHeight)
{
this.selectHeight = selectHeight;
}
public void setHasAllSelector(boolean hasAllSelector)
{
this.hasAllSelector = hasAllSelector;
}
}tld文件（multiSelect.tld）：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
<taglib>
<tlibversion>1.0</tlibversion>
<jspversion>1.1</jspversion>
<shortname>multiSelectTaglib</shortname>
<uri>/multiSelectTaglib</uri>
<tag>
<name>multiSelect</name>
<tagclass>com.zte.ppm.baseutil.business.multiSelectTaglib.service.MultiSelectTaglib</tagclass>
<bodycontent>JSP</bodycontent>
<info>check if the user have the right access</info>
<attribute>
<name>items</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>curIdVal</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>idParams</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>nameParams</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>textStyle</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>readonly</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>hasSelectImg</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>hasClearImg</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>selectHeight</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>selectWidth</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>hasAllSelector</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>
使用时导入相应tld文件和JS文件以及jQuery包：
<%@ taglib uri="/WEB-INF/multiSelect.tld" prefix="mSelect"%>
<script type="text/javascript" src="${appRoot}/js/multiSelect.js"></script>
<script type="text/javascript" src="${appRoot}/js/jquery/jquery-1.4.2.min.js"></script>
使用方法：
<mSelect:multiSelect nameParams="con.unitName" items="${dpgReportForm.operateUnitList}"
curIdVal="${dpgReportForm.con.unitName}" idParams="con.unitName"
hasClearImg="true" selectHeight="200px" hasAllSelector="true"/>
效果：
如果要实现注释中说的自定义下拉框样式且将全选选择框置顶，可以另外定义两个div，一个放全选按钮，一个放下面的选择数据。
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