实例解读Ajax与servlet交互的方法
本文以实例形式剖析了Ajax与servlet的交互,并且代码中有较为详细的注释,以帮助大家阅读理解。具体的实现方法如下:
1.JavaScript部分
varreq; /*通过异步传输XMLHTTP发送参数到ajaxServlet,返回符合条件的XML文档*/ varurl; functiongetResult() { varf=document.getElementById("form_pub"); varkey=f.s.options[f.s.selectedIndex].text;//获取对select中文本的引用 if(window.XMLHttpRequest) { req=newXMLHttpRequest(); url="ajaxServlet?action="+key+"&bm=UTF-8"; }elseif(window.ActiveXObject) { req=newActiveXObject("Microsoft.XMLHTTP"); url="ajaxServlet?action="+key+"&bm=gbk"; } if(req) { req.open("GET",url,true); req.setRequestHeader("Content-Type","text/html;charset=UTF-8"); //这里如果不设定头部则会导致firfox发送数据错误,servlet接受到的参数为乱码,在IE中正常 req.onreadystatechange=complete; req.send(null); //req.setRequestHeader("Content-Type","text/xml;charset=UTF-8"); } } /*分析返回的XML文档*/ functioncomplete(){ if(req.readyState==4) { if(req.status==200) { varitems=document.getElementById("belong"); //以下为解析返回的XML文档 varxmlDoc=req.responseXML; varNode=xmlDoc.getElementsByTagName("type_name"); //varstr=newArray(); varstr=null; //清空工作 items.innerHTML="";//删除一个select内的全部内容 for(vari=0;i<Node.length;i++) { str=Node[i]; //alert(str.childNodes[0].nodeValue); varobjectOption=document.createElement("option"); items.options.add(objectOption); //firfox不支持innerText必须用textContent代替 if(window.ActiveXObject) {objectOption.innerText=str.childNodes[0].nodeValue;} else {objectOption.textContent=str.childNodes[0].nodeValue;} } } } }
2.servlet端:
packageajax; importjava.io.IOException; importjava.io.PrintWriter; importjavax.servlet.ServletException; importjavax.servlet.http.HttpServlet; importjavax.servlet.http.HttpServletRequest; importjavax.servlet.http.HttpServletResponse; importData_GetConn.GetConn;//这个包是自己写的为获取对mysql的引用 importjava.sql.*;//这个包必须有!! publicclassajaxServletextendsHttpServlet{ //privatestaticfinalStringCONTENT_TYPE="text/xml;charset=UTF-8";//这里最好统一用UTF-8进行编码 publicvoidinit()throwsServletException{} publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException { response.setContentType("text/xml;charset=UTF-8"); //以下两句为取消在本地的缓存 response.setHeader("Cache-Control","no-cache"); response.setHeader("Pragma","no-cache"); PrintWriterout=response.getWriter(); Stringaction=request.getParameter("action"); Stringbm=request.getParameter("bm"); if(("gbk").equals(bm)) { action=newString(action.getBytes("ISO-8859-1"),"gbk");//将获得的数据用gbk从新编码!(感谢董卫老师) } else { action=newString(action.getBytes("ISO-8859-1"),"gbk"); } try { GetConnwq=newGetConn(); Connectioncon=wq.getCon(); Statementstmt=con.createStatement(); ResultSetrs=stmt.executeQuery("selectitemsfromclasswheremain='"+action+"'"); StringBuffersb=newStringBuffer(); sb.append("<type>"); while(rs.next()) { sb.append("<type_name>"+rs.getString(1)+"</type_name>"); } //sb.append("<type_name>"+action+"</type_name>"); sb.append("</type>"); out.write(sb.toString());//注意这里向jsp输出的流,在script中的截获方法 out.close(); stmt.close(); con.close(); } catch(Exceptionex) { } } }