ajax
ajax（Asynchronous JavaScript and XML, 非同步 JavaScript 及 XML技术）;两大功能:在不重新读取页面的情況下对服务器送出请求，如连动下拉列表呀；
解析、使用 XML 文件.
function getActDefined(stateVal); {var url = "/servlet/InitAddCustSelect?servCode=" + stateVal;//stateVal是从页面上传到后台servlet的值。 if (window.XMLHttpRequest); {//// Mozilla, Safari.....req = new XMLHttpRequest();; } else if (window.ActiveXObject); {//IE(可跨浏览器);req = new ActiveXObject("Microsoft.XMLHTTP");; } if(req); {req.open("GET", url, true);;req.onreadystatechange = complete;//指定的函式名称后不加括号req.send(null);; }}
complete函数，接受返回值并解析。
function complete(); { if (req.readyState == 4); {//request的返回状态；4表示数据已传回if (req.status == 200); {//http接受数据状态；200ok,404文件未找到；500服务器内部错var values = req.responseXML.getElementsByTagName("actDefinedId");;//解析var lables = req.responseXML.getElementsByTagName("name");;document.theForm.Act_define_id.length = values.length;for(var i = 0; i < values.length; i++); { document.theForm.Act_define_id.options.value = values.firstChild.data;//读入下拉表。document.theForm.Act_define_id.options.text = lables.firstChild.data;}}}}
处理业务的servlet:
import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.sql.*;import topway.common.Helper;import topway.business.SelectParam;public class InitAddCustSelect extends HttpServlet {public InitAddCustSelect(); { super();;}public void destroy(); { super.destroy();;}public void doGet(HttpServletRequest request, HttpServletResponse response); throws ServletException, IOException { response.setContentType("text/xml;CHARSET=utf8");; response.setHeader("Cache-Control", "no-cache");; String state = request.getParameter("servCode");;//接收request传来的参数 StringBuffer sb = new StringBuffer( "<?xml version=\"1.0\" encoding=\"GB2312\"?>");; sb.append("<addCustSelect>");; Connection conn = null; try { conn = Helper.getConnection();; SelectParam selectBean = new SelectParam();; ResultSet actDefine = selectBean.getActDefine(conn, state);; while (actDefine.next();); { sb.append("<actDefinedId>" + actDefine.getString(1); + "</actDefinedId>");; sb.append("<name>" + actDefine.getString(2); + "</name>");; sb.append("<prepayFee>" + actDefine.getString(3); + "</prepayFee>");; sb.append("<firstInstallFee>" + actDefine.getString(4); + "</firstInstallFee>");; sb.append("<ipnums>" + actDefine.getString(5); + "</ipnums>");; } } catch (SQLException ex); { ex.printStackTrace();; } finally { try { conn.close();; } catch (SQLException ex); { ex.printStackTrace();; } } sb.append("</addCustSelect>");; PrintWriter out = response.getWriter();; out.write(sb.toString(););;//输出 out.close();;}public void doPost(HttpServletRequest request, HttpServletResponse response); throws ServletException, IOException { doGet(request, response);;}}
加载webapplication时初始化servlet,在web.xml中：
<servlet> <servlet-name>ServletNames</servlet-name><servlet-class>cn.common.InitAddCustSelect</servlet-class></servlet><servlet-mapping><servlet-name>ServletNames</servlet-name><url-pattern>/servlet/InitAddCustSelect</url-pattern></servlet-mapping>
页:
[1]