Wednesday, 7 November 2012

Spring MVC REST Calls With Ajax

This post provides a simple example of REST calls to a Spring MVC web application. It is based on the Serving Static Resources With Spring MVC and Fetching JSON With Ajax In Spring MVC Context example. The code is available on GitHub in the Spring-REST-With-Ajax directory.

Main Page

Our main page contains four buttons linked to Javascript functions performing Ajax calls:
...
<body>
<h1>Welcome To REST With Ajax !!!</h1>
<button type="button" onclick="RestGet()">GET</button>
<button type="button" onclick="RestPut()">PUT</button>
<button type="button" onclick="RestPost()">POST</button>
<button type="button" onclick="RestDelete()">DELETE</button>
</body>
...

Javascript

Our Javascript file contains the four functions:
var prefix = "/spring-rest-with-ajax";

var RestGet = function() {
        $.ajax({
        type: 'GET',
        url:  prefix + "/MyData/" + Date.now(),
        dataType: 'json',
        async: true,
        success: function(result) {
            alert("At " + result.time
                + ": " + result.message);
        },
        error: function(jqXHR, textStatus, errorThrown) {
            alert(jqXHR.status + " " + jqXHR.responseText);
        }
   });
}

var RestPut = function() {

    var JSONObject= {
        "time": Date.now(),
        "message": "User PUT call !!!"
    };
 
    $.ajax({
        type: 'PUT',
        url:  prefix + "/MyData",
        contentType: "application/json; charset=utf-8",
        data: JSON.stringify(JSONObject),
        dataType: 'json',
        async: true,
        success: function(result) {
            alert("At " + result.time
                + ": " + result.message);
        },
        error: function(jqXHR, textStatus, errorThrown) {
            alert(jqXHR.status + " " + jqXHR.responseText);
        }
    });
}

var RestPost = function() {
        $.ajax({
        type: 'POST',
        url:  prefix + "/MyData",
        dataType: 'json',
        async: true,
        success: function(result) {
            alert("At " + result.time
                + ": " + result.message);
        },
        error: function(jqXHR, textStatus, errorThrown) {
            alert(jqXHR.status + " " + jqXHR.responseText);
        }
    });
}

var RestDelete = function() {
        $.ajax({
        type: 'DELETE',
        url:  prefix + "/MyData/" + Date.now(),
        dataType: 'json',
        async: true,
        success: function(result) {
            alert("At " + result.time
                + ": " + result.message);
        },
        error: function(jqXHR, textStatus, errorThrown) {
            alert(jqXHR.status + " " + jqXHR.responseText);
        }
    });
}

Controller

Our controller captures the REST calls and returns a JSON. In a real applications, one would perform CRUD operations rather than returning JSONs:
@Controller
@RequestMapping(value = "/MyData")
public class MyRESTController {

    @RequestMapping(value="/{time}", method = RequestMethod.GET)
    public @ResponseBody MyData getMyData(
            @PathVariable long time) {
  
        return new MyData(time, "REST GET Call !!!");
    }
 
    @RequestMapping(method = RequestMethod.PUT)
    public @ResponseBody MyData putMyData(
            @RequestBody MyData md) {
  
        return md;
    }
 
    @RequestMapping(method = RequestMethod.POST)
    public @ResponseBody MyData postMyData() {
 
        return new MyData(System.currentTimeMillis(),
            "REST POST Call !!!");
    }

    @RequestMapping(value="/{time}", method = RequestMethod.DELETE)
    public @ResponseBody MyData deleteMyData(
            @PathVariable long time) {
  
        return new MyData(time, "REST DELETE Call !!!");
    }
}

Running The Example

Once compiled, the example can be run with mvn tomcat:run. Then, browse:

  http://localhost:8585/spring-rest-with-ajax/

The main page will be displayed:



If you click on any button, a pop-up will be displayed:


See here for more about REST • More Spring related posts here.