真善美

本文参照http://www.blogjava.net/daizhenghenry/archive/2008/05/21/201987.html

原理：通过页面操作调用js方法，在js方法里进行查询数据库。
1 先下载dwr.jar，放到lib目录下。
2 web.xml中追加
 <servlet>
  <servlet-name>dwr</servlet-name>
  <servlet-class>
   org.directwebremoting.servlet.DwrServlet
  </servlet-class>
  <init-param>
   <param-name>debug</param-name>
   <param-value>true</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>dwr</servlet-name>
  <url-pattern>/dwr/*</url-pattern>
 </servlet-mapping>
3 新建dwr.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://www.getahead.ltd.uk/dwr/dwr20.dtd">

<dwr>
    <allow>
        <create javascript="Hello" creator="new">
            <param name="class" value="com.train.action.TrainQueryAction"></param>
        </create>
    </allow>
</dwr>

4 jsp页面

function sayHello() {
Hello.query(valuestation, change);
}
function change(datae){
         if(datae!=null&&datae!=""){  
             //得到表格中的行数
             var counte = document.getElementById('tabe').rows.length;
             //如果表中存在行,将所有行删除
             if(counte >0){
                 for(var i=counte-1;i>=0;i--){
                     document.getElementById('tabe').deleteRow(i);
                 }
             }
             //如果存在相关搜索记录       
             if(datae.length > 0){
                 document.getElementById('Relatede').style.display = '';
                 document.getElementById('xe').style.display = '';
                 for(var i=0;i<datae.length;i++){
               var objTr6 = document.getElementById('tabe').insertRow();                
                     var objTd16 = objTr6.insertCell(0);
                     objTd16.innerHTML = "<input readonly type='text' "
                     +"size='10' name='txtHistorye' style='border:none;background:#FFFFFF'"
                     +" value='"+trim(datae[i])+"' onmouseover='overChangeColor(this)'"
                     +" onmouseleave='leaveChangeColor(this)' "
                     +"onclick='clickHistorye(this)'>";
                     }
             }else{
                 document.getElementById('Relatede').style.display = 'none';
             }
         }else{
                 document.getElementById('Relatede').style.display = 'none';
             }
        }
<table width="80%" border="1" align="center">
    <tr>
     <td align="left" nowrap="nowrap">
      <input type="radio" name="radio" value="esStation">
      站站查询：
      <br>
      发站:
      <html:text name="trainQueryForm" property="startStation" maxlength="10" onfocus="textChange('esStation')" onkeyup="sayHello()" />
      <div id="Relateds"  style="position:absolute;background-color='#F7F7F7';display: 'none';">
       <table id="tabs" cellpadding="0" border="0" cellspacing="0">
       </table>
       &nbsp;
       &nbsp;
       &nbsp;
       &nbsp;
       &nbsp;
       &nbsp;
       &nbsp;
       <a id="xs" href='javascript:;' onclick='myClose()'
        style="display: none">关闭</a>
      </div>
    </td>
    </tr>
   </table>
5 java文件
public class TrainQueryAction extends BaseAction {
 public List<?> query(String content,HttpServletRequest request) {
  List<?> elist=null;
  try {
   elist = trainService.queryStationName(content);
  } catch (Exception e) {
   e.printStackTrace();
  }
  return elist;
 }
}