Jquery implements the secondary linkage of the drop down menu by using json objects to display the linkage from the DB value

Struts2 and Ajax are used to transfer json objects, and then the secondary linkage of menus is realized

The following is the source code of my js file:

 
var mail={ 
//Initialize the
init:{ 
//Initialization data
initdata:{ 
did:'', 
ttitle:'', 
sendpassword:'', 
description:'' 
}, 
//Initialization event
initevent:{ 
DataEvent:function(){ 
$("#did").unbind("change");//Gets a level one menu to bind events
$("#did").bind("change",function(){ 
//alert($(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 secondary menu
uidoption.empty();//Empty the list
for(var i=0;i<data.users.length;i++){ 
//Fill it with options, through the loop
uidoption.append("<option value="+data.users[i].uid+ " >"+data.users[i].username+"</option>" ); 
} 
});</span> 
}, 
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 your password !"); 
return false; 
} 
else if(mail.init.initdata.ttitle==""){ 
alert(" Please enter the theme! "); 
return false ; 
} 
else if(mail.init.initdata.description==""){ 
alert(" Please enter the content! "); 
return false; 
} 
else 
return true; 
}); 
} 
} 
} 
} 

$().ready(function(){ 
mail.init.initevent.DataEvent(); 
mail.init.initevent.submitCheck(); 

}); 

This is the action in the background:

 
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:

 
<package name="users" namespace="/" extends="json-default"> 
<action name="mailAction_showUsers" method="showUsers" class="mailAction"> 
<result type="json"></result> 
</action> 

</package> 

Foreground JSP page:

 
<td width="65px"> recipient </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> 

This is a screenshot of the run after implementation:
< img SRC = "border = 0 / / files.jb51.net/file_images/article/201403/201403271121271.gif? 2014227112141 ">  
Write to someone in need... Refer to