我需要通过POST发送JSON并获得响应的帮助

Question

I need to send a json object via post and i cannot get it working. I have it so that it returns successfully but the response is empty and i cannot figure out why things i have tried are

new Ajax.Request("http://twittersentiment.appspot.com/api/bulkClassifyJsonRequests", {
method: "post",
postBody:JSONstring,
onSuccess: function(transport){
var response = transport.responseText;
alert("Success@ \n" + transport.responseText + "no response");
},
onFailure: function(){alert("try again")}
});

and

var http = new XMLHttpRequest();
http.open("POST","http://twittersentiment.appspot.com/api/bulkClassifyJsonRequests",true);
http.onreadystatechange = function() {
if(http.readyState == 4)
{
    if(http.status == 200)
    {
        document.write(http.response.data);
}
else
{
    alert(http.statusText);
}
} 
};
http.send(JSONstring);

Answer 1

The problem is that you're trying to send a cross-domain request (it violates the same origin policy ). This is a security issue and is not allowed by browsers. If twittersentiment.appspot.com provides a JSONP option, you can utilize that instead. Otherwise, you'll have to look into proxying through your website or similar ideas.

Edit
Note: This only applies to using AJAX. Also, After looking at their api docs , it seems they do support JSONP for their "Classification Service". Perhaps you can use it with the "Bulk Classification Service (JSON)" as well?

Answer 2

The Same Origin Policy is preventing that call from happening. You could install a proxy server in between to make those calls, and return the output to your AJAX script. See Why You Need a Proxy for more details.