Ajax and Spring MVC Controller

Note

Before you through two cases below, make sure you check your web.xml and get the <url-pattern>: - If your web.xml set up default url-pattern /, when you refer a link, you don't need to add any suffix on it. - If your web.xml set up any url-pattern, such as html or htm, when you refere a link, in ajax or windown.location.href, you need to add html or htm suffix after it. But don't add these suffix in spring controller request mapping.

Case 1. Pass JSON Data to Controller in Ajax Call, using $.ajax()

Notes on 01/13/2015: I had trouble using $.post() to post JSON data. I doubt something is wrong but I haven't figure out why. Currently I just use $.ajax()*

PROS

Ajax is good for large dataset, so you can avoid possible "timeout" problem in case 2.

Ajax has success and error option, so you can check status of ajax call, and give response based on feedback.

CONS

You need to come back this page after an ajax call!**, no matter you success or fail.

So, if you want to go to another page, you need to use another window.href or other functions to call another controller, then follow that controller to go to another page.

Process of using Ajax:

//Assume we have a json object 'json'
$.ajax({
    headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
    }
});

TIP

You may want to substitude application/json with application/html to avoid possible.

Case 2. Pass JSON Data as URL parameter, and Handle it in Spring MVC Controller

PROS

You are free to go to another page or call other controllers after you pass data to controller.

CONS

Not good to handle large dataset. If you put too much stuff in URL, you may get "time out" problem.

One of the easiest way to handle json object is to pass it directly to URL. I tried following methods:

1. Pass data as pure json object, and make it as part of URL
2. Pass data as pure jsob object, and make it as a parameter in URL
3. Pass data as a string, and make it as part of URL
4. Pass data as a astring, and make it as a parameter in URL

Assume the code for JSON object in JavaScript is:

var json = [];
var obj = {};
obj.age = 5;
obj.name = "test";
json.push(obj);

So the code for JSP page can be:

var testUrl = "/project/json_operation/" + json;
window.location.href = testUrl;

var testUrl = "/project/json_operation?json=" + json;
window.location.href = testUrl;

var testUrl = "/project/json_operation/" + JSON.stringify(json);
window.location.href = testUrl;

var testUrl = "/project/json_operation?json=" + JSON.stringify(json);
window.location.hre = testUrl;

And the code for Spring Controller can be:

/*
*1 and 3: not work.
*For 1: Spring will recognize json as [object%20Object] in url
*For 1 and 3: Spring cannot find
*/
@RequestMapping(value="/springtest/{jsonstuff}")
public ModelAndView test(@PathVariable("jsonstuff") JSONObject json){
//Or @PathVaraible("jsonstuff") String json
}