com.google.gwt.jsonp.client

Class JsonpRequestBuilder

java.lang.Object

com.google.gwt.jsonp.client.JsonpRequestBuilder

public class JsonpRequestBuilder
extends Object

Class to send cross domain requests to an http server. The server will receive a request including a callback url parameter, which should be used to return the response as following:

<callback>(<json>);

where <callback> is the url parameter (see setCallbackParam(String)), and <json> is the response to the request in json format. This will result on the client to call the corresponding AsyncCallback.onSuccess(Object) method.

If needed, errors can be handled by a separate callback:

<failureCallback>(<error>);

where <error> is a string containing an error message. This will result on the client to call the corresponding AsyncCallback.onFailure(Throwable) method. See setFailureCallbackParam(String).

Example using JSON Google Calendar GData API:

 String url = "http://www.google.com/calendar/feeds/[email protected]/public/full" +
     "?alt=json-in-script";
 JsonpRequestBuilder jsonp = new JsonpRequestBuilder();
 jsonp.requestObject(url,
     new AsyncCallback<Feed>() {
       public void onFailure(Throwable throwable) {
         Log.severe("Error: " + throwable);
       }

       public void onSuccess(Feed feed) {
         JsArray<Entry> entries = feed.getEntries();
         for (int i = 0; i < entries.length(); i++) {
           Entry entry = entries.get(i);
           Log.info(entry.getTitle() +
                    " (" + entry.getWhere() + "): " +
                    entry.getStartTime() + " -> " +
                    entry.getEndTime());
         }
       }
     });
 

This example uses these overlay types:

 class Entry extends JavaScriptObject {
   protected Entry() {}

   public final native String getTitle() /*-{
     return this.title.$t;
   }-*/;

   public final native String getWhere() /*-{
     return this.gd$where[0].valueString;
   }-*/;

   public final native String getStartTime() /*-{
     return this.gd$when ? this.gd$when[0].startTime : null;
   }-*/;

   public final native String getEndTime() /*-{
     return this.gd$when ? this.gd$when[0].endTime : null;
   }-*/;
 }

 class Feed extends JavaScriptObject {
   protected Feed() {}

   public final native JsArray<Entry> getEntries() /*-{
     return this.feed.entry;
   }-*/;
 }
 

Constructor Summary

Constructors

Constructor and Description
JsonpRequestBuilder()

Method Summary

Modifier and Type	Method and Description
String	getCallbackParam() Returns the name of the callback url parameter to send to the server.
String	getFailureCallbackParam() Returns the name of the failure callback url parameter to send to the server.
int	getTimeout() Returns the expected timeout (ms) for this request.
JsonpRequest<Boolean>	requestBoolean(String url, AsyncCallback<Boolean> callback)
JsonpRequest<Double>	requestDouble(String url, AsyncCallback<Double> callback)
JsonpRequest<Integer>	requestInteger(String url, AsyncCallback<Integer> callback)
<T extends JavaScriptObject> JsonpRequest<T>	requestObject(String url, AsyncCallback<T> callback) Sends a JSONP request and expects a JavaScript object as a result.
JsonpRequest<String>	requestString(String url, AsyncCallback<String> callback)
void	send(String url) Sends a JSONP request and does not expect any results.
JsonpRequest<Void>	send(String url, AsyncCallback<Void> callback) Sends a JSONP request, does not expect any result, but still allows to be notified when the request has been executed on the server.
void	setCallbackParam(String callbackParam)
void	setFailureCallbackParam(String failureCallbackParam)
void	setPredeterminedId(String id)
void	setTimeout(int timeout)

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Constructor Detail

JsonpRequestBuilder

public JsonpRequestBuilder()

Method Detail

getCallbackParam

public String getCallbackParam()

Returns the name of the callback url parameter to send to the server. The default value is "callback".

getFailureCallbackParam

public String getFailureCallbackParam()

Returns the name of the failure callback url parameter to send to the server. The default is null.

getTimeout

public int getTimeout()

Returns the expected timeout (ms) for this request.

requestBoolean

public JsonpRequest<Boolean> requestBoolean(String url,
                                            AsyncCallback<Boolean> callback)

requestDouble

public JsonpRequest<Double> requestDouble(String url,
                                          AsyncCallback<Double> callback)

requestInteger

public JsonpRequest<Integer> requestInteger(String url,
                                            AsyncCallback<Integer> callback)

requestObject

public <T extends JavaScriptObject> JsonpRequest<T> requestObject(String url,
                                                                  AsyncCallback<T> callback)

Sends a JSONP request and expects a JavaScript object as a result. The caller can either use JSONObject to parse it, or use a JavaScript overlay class.

requestString

public JsonpRequest<String> requestString(String url,
                                          AsyncCallback<String> callback)

send

public void send(String url)

Sends a JSONP request and does not expect any results.

send

public JsonpRequest<Void> send(String url,
                               AsyncCallback<Void> callback)

Sends a JSONP request, does not expect any result, but still allows to be notified when the request has been executed on the server.

setCallbackParam

public void setCallbackParam(String callbackParam)

Parameters:

callbackParam - The name of the callback url parameter to send to the server. The default value is "callback".

setFailureCallbackParam

public void setFailureCallbackParam(String failureCallbackParam)

Parameters:

failureCallbackParam - The name of the failure callback url parameter to send to the server. The default is null.

setPredeterminedId

public void setPredeterminedId(String id)

setTimeout

public void setTimeout(int timeout)

Parameters:

timeout - The expected timeout (ms) for this request. The default is 10s.