问题
i'm learning about calls to ajax so i'm trying to get the value of ('#abcd') (a html select). I'm using this line:
abcdVal = combo.options[combo.selectedIndex].value
When this value change i must store his value in a var like abcdVal for pass to servlet with:
var data = {"text" : abcdVal};
j("#mybutton").click(function(){
j.ajax({method: 'POST',
url: "/bin/company/repo",
dataType: 'JSON',
data: data,
success:function(result){
alert(result);
j("#demo").html('');
j('#demo').html(result);
}});
});
i got the value and put in response as a text plain, but in html page i see:
[{"text":null,"value":10}]
Instead of [{"text":(selected value of html select),"value":10}]
i doing something wrong then i pass the data to servlet. how must i pass this var correctly?
My code
Javascript code
<script type="text/javascript">
var j = jQuery.noConflict();
var abcdVal;
j(document).ready(function(){
//get a reference to the select element
//request the JSON data and parse into the select element
j.ajax({
url: '/bin/company/repo',
dataType:'JSON',
success:function(data){
//clear the current content of the select
j('#abcd').html('');
//iterate over the data and append a select option
jQuery.each(data, function(text, value){
j('#abcd').append('<option id="' + value.value + '">' + value.text + '</option>');
});
},
error:function(){
//if there is an error append a 'none available' option
j('#abcd').html('<option id="-1">none available</option>');
}
});
j("#abcd").change(function(){
var combo = document.getElementById('abcd');
if(combo.selectedIndex<0)
alert('No hay opcion seleccionada');
else
abcdVal = combo.options[combo.selectedIndex].value;
alert('La opcion seleccionada es: '+combo.options[combo.selectedIndex].value);
});
var data = {"text" : abcdVal};
alert(data);
j("#mybutton").click(function(){
j.ajax({method: 'POST',
url: "/bin/company/repo",
dataType: 'JSON',
data: data,
success:function(result){
alert(result);
j("#demo").html('');
j('#demo').html(result);
}});
});
})
</script>
Servlet code
@Override
protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException,
IOException {
String text = (String) request.getParameter("text");
response.setHeader("Content-Type", "text/html; charset=UTF-8");
StringWriter writer = new StringWriter();
TidyJSONWriter json = new TidyJSONWriter(writer);
try
{
json.array();
//loop through your options and create objects as shown below
json.object();
json.key("text");
json.value(text);
json.key("value");
json.value(10);
json.endObject();
//end your array
json.endArray();
} catch(JSONException e) {
e.printStackTrace();
}
response.getWriter().write(writer.toString()); // Write response body.
}
回答1:
I did this changes for solve my problem:
1) In ajax call change method: POST by type: 'POST'.
2) Add even.preventDefault() before call to ajax for dont use submit by default.
3) Change the form i handled data request. If i dont pass a form i need do this for retrieve request parameter like @Sabya explain.
4) Handle json inside of success (ajax) for show selection of html select.
So the code is the next:
JavaScript
<script type="text/javascript">
var j = jQuery.noConflict();
var abcd = document.getElementById("abcd");
var selection = abcd.options[abcd.selectedIndex].value
j(document).ready(function(){
j.ajax({
url: '/bin/company/repo',
dataType:'JSON',
success:function(data){
jQuery.each(data, function(text, value){
j('#abcd').append('<option id="' + value.value + '">' + value.text + '</option>');
});
},
error:function(){
//if there is an error append a 'none available' option
j('#abcd').html('<option id="-1">none available</option>');
}
});
j("#abcd").live('change',function(){
var combo = document.getElementById('abcd');
if(combo.selectedIndex<0)
alert('no option selected');
else
selection = combo.options[combo.selectedIndex].value;
});
j('form').on('submit', function(e){
event.preventDefault();
j.ajax({type: 'POST',
contentType: "application/json; charset=utf-8",
url: "/bin/company/repo",
dataType: 'JSON',
data: JSON.stringify({ "text": selection }),
success:function(data){
jQuery.each(data, function(text, value){
j('#demo').html('');
j('#demo').html(value.text);
});
}});
});
})
</script>
Servlet
@Override
protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException,
IOException {
response.setHeader("Content-Type", "application/json");
PrintWriter out = response.getWriter();
StringWriter writer = new StringWriter();
TidyJSONWriter json = new TidyJSONWriter(writer);
StringBuilder buffer = new StringBuilder();
BufferedReader reader = request.getReader();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String data = buffer.toString();
try
{
JSONObject jsonObj = new JSONObject(new String(data));
json.array();
//loop through your options and create objects as shown below
json.object();
json.key("text");
json.value(jsonObj.get("text"));
json.endObject();
//end your array
json.endArray();
} catch(JSONException e) {
e.printStackTrace();
}
out.write(writer.toString());
}
回答2:
Use .live() in place of .change() because you select element is dynamic.
j("#abcd").live('change', function(){
var combo = document.getElementById('abcd');
if(combo.selectedIndex<0)
alert('No hay opcion seleccionada');
else
abcdVal = combo.options[combo.selectedIndex].value;
alert('La opcion seleccionada es: '+combo.options[combo.selectedIndex].value);
});
回答3:
Can you inspect the servlet call in network panel of chrome and check the Request-Header and/or form data ?
Not sure about your problem in javascript , but if you are getting an NPE in your servlet , that might be because you are not POSTing it as a form data and trying to retrieve it from request parameter.
Accessing the data sent as a Request Payload is a little different than accessing the form data.
The following snippet might help you in case you find that you are POSTing the JSON to the servlet as a Request Payload.
BufferedReader reader = req.getReader();
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String requestData = buffer.toString();
//TODO: Retrieve required fields from this requestData string .
来源：https://stackoverflow.com/questions/29469366/pass-json-data-to-servlet-dopost-with-jquery-ajax