The two-level linkage of the Pull-down menu using the JSON object to display linkage from DB value

  This article mainly introduces the implementation of the jquery drop-down menu two-level linkage using JSON objects from DB value display linkage, need friends can refer to the following

Use STRUTS2 and Ajax to implement JSON object transmission, and then implement menu two-level linkage     Below is my JS file original code:    code as follows: VAR mail={ //initialization   init:{  //initialization of data   initdata:{  did: ',  ttitle: ',  sendpassword: ',  description: '  },  //initialization event   initevent:{  dataevent:function () {  $ ("#did"). Unbind ("change"); Get a level menu, bind event   $ ("#did"). Bind (' Change ', function () { //alert ($ (this). Val ());  mail.init.initdata.did=$ (This). Val ();  //alert (Mail.init.initdata.did);  mail.init.initevent.getuser (); }); },  <span Style = "COLOR: #ff0000;" >getuser:function () {  $.post ("mailaction_showusers?did=" +mail.init.initdata.did,null,function (data) {   var uidoption=$ ("#uid")//Get level Two menu   uidoption.empty ()//Empty list   for (Var i=0;i<data.users.length;i+ +) { //Add option to the inside, through the loop   uidoption.append ("<option value=" +data.users[i].uid+ ">" +data.users[i). Username+ "</option>"); } });</span> },&nbsP Submitcheck:function () {  $ ("#send"). Unbind ("click");  $ ("#send"). Bind ("click", Function () {  mail.init.initdata.description=$ ("input[type= ' textarea ']"). Text ();  mail.init.initdata.sendpassword=$ (" Input[name= ' Sendpassword '). Val ();  mail.init.initdata.ttitle=$ ("Input[name= ' Ttitle ')"). Val ();    if (mail.init.initdata.sendpassword== "") {  alert ("Please enter password!");   Return false; }  else if (mail.init.initdata.ttitle== "") {  alert ("Please enter a theme!") ");  return false; }  else if (mail.init.initdata.description==" ") {  alert (" Enter the content! "). ");  return false; }  else  return true; }); } -} } }    $ (). R Eady (function () {  mail.init.initevent.DataEvent ();  Mail.init.initevent.submitCheck ();   });     This is the backstage action:    code as follows: Private int did;  public String getdid () {  ... }  Public void Setdid (Strign did) {  ... }  PUBlic String showusers () {    users= (arraylist<user>) This.userService.getUsersByDid (did);  System.out.println (users.size () + "...");  return success; }    struts.xml configuration:    code is as follows: <package name= "Users" namespace= "/" extends= "Json-default" >  <action name= "Mailaction_showusers" Method= "Showusers" class= "mailaction" >  <result type= "JSON" ></result>  </action>     </package>    foreground JSP page:    code as follows: <td width= "65px" > Receiver </td>  <td> <s:select list= "departmentlist" listkey= "did" listvalue= "Dname" id= "did" Name= "did" ></s:select >  <s:select list= "users" listkey= "UID" listvalue= "username" id= "UID" name= "UID" ></s:select>   </td>