Java tutorial
package com.google.gwt.query.client.plugins.ajax; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.Element; import com.google.gwt.http.client.Request; import com.google.gwt.http.client.RequestBuilder; import com.google.gwt.http.client.RequestBuilder.Method; import com.google.gwt.http.client.RequestCallback; import com.google.gwt.http.client.RequestException; import com.google.gwt.http.client.Response; import com.google.gwt.query.client.Function; import com.google.gwt.query.client.GQuery; import com.google.gwt.query.client.Properties; import com.google.gwt.query.client.builders.JsonBuilder; import com.google.gwt.query.client.js.JsUtils; import com.google.gwt.query.client.plugins.Plugin; import com.google.gwt.user.client.ui.FormPanel; /** * Ajax class for GQuery. * * The jQuery library has a full suite of AJAX capabilities, but GWT is plenty of classes to get * data from server side: RPC, XHR, RF, etc. * * This class is not a substitute for the GWT utilities, but a complement to get server data in a * jquery way, specially when querying non java backends. * * We do not pretend to clone all the jquery Ajax API inside gquery, just take its syntax and to * implement the most popular usage of it. This implementation is almost thought to be used as an * alternative to the GWT-XHR, GWT-XML and GWT-JSON modules. * */ public class Ajax extends GQuery { /** * Ajax Settings object */ public interface Settings extends JsonBuilder { String getContentType(); Element getContext(); Properties getData(); String getDataString(); String getDataType(); Function getError(); Properties getHeaders(); String getPassword(); Function getSuccess(); int getTimeout(); String getType(); String getUrl(); String getUsername(); Settings setContentType(String t); Settings setContext(Element e); Settings setData(Properties p); Settings setDataString(String d); Settings setDataType(String t); Settings setError(Function f); Settings setHeaders(Properties p); Settings setPassword(String p); Settings setSuccess(Function f); Settings setTimeout(int t); Settings setType(String t); Settings setUrl(String u); Settings setUsername(String u); } public static final Class<Ajax> Ajax = registerPlugin(Ajax.class, new Plugin<Ajax>() { public Ajax init(GQuery gq) { return new Ajax(gq); } }); public static void ajax(Properties p) { Settings s = createSettings(); s.load(p); ajax(s); } /** * Perform an ajax request to the server. * * * Example: * * <pre> import static com.google.gwt.query.client.GQ.* ... Properties properties = $$("dataType: xml, type: post; data: {q: 'gwt'}, headers: {X-Powered-By: GQuery}"); ajax("test.php", new Function() { public void f() { Element xmlElem = getData()[0]; System.out.println($("message", xmlElem)); } }, new Function(){ public void f() { System.err.println("Ajax Error: " + getData()[1]); } }, properties); * </pre> * * @param url The url to connect * @param onSuccess a function to execute in the case of success * @param onError the function to execute on error * @param settings a Properties object with the configuration of the Ajax request. */ public static void ajax(Settings settings) { final Function onSuccess = settings.getSuccess(); if (onSuccess != null) { onSuccess.setElement(settings.getContext()); } final Function onError = settings.getError(); if (onError != null) { onError.setElement(settings.getContext()); } Method httpMethod = resolveHttpMethod(settings); String data = resolveData(settings, httpMethod); String url = resolveUrl(settings, httpMethod, data); final String dataType = settings.getDataType(); if ("jsonp".equalsIgnoreCase(dataType)) { int timeout = settings.getTimeout(); getJSONP(url, onSuccess, onError, timeout); return; } final RequestBuilder requestBuilder = createRequestBuilder(settings, httpMethod, url, data); requestBuilder.setCallback(new RequestCallback() { public void onError(Request request, Throwable exception) { if (onError != null) { onError.f(null, exception.getMessage(), request, null, exception); } } public void onResponseReceived(Request request, Response response) { if (response.getStatusCode() > 202) { if (onError != null) { onError.fe(response.getText(), "error", request, response); } } else if (onSuccess != null) { Object retData = null; try { if ("xml".equalsIgnoreCase(dataType)) { retData = JsUtils.parseXML(response.getText()); } else if ("json".equalsIgnoreCase(dataType)) { retData = JsUtils.parseJSON(response.getText()); } else { retData = response.getText(); } } catch (Exception e) { if (GWT.getUncaughtExceptionHandler() != null) { GWT.getUncaughtExceptionHandler().onUncaughtException(e); } } onSuccess.fe(retData, "success", request, response); } } }); try { requestBuilder.send(); } catch (RequestException e) { if (onError != null) { onError.f(null, -1, null, null, e); } } } private static RequestBuilder createRequestBuilder(Settings settings, Method httpMethod, String url, String data) { RequestBuilder requestBuilder = new RequestBuilder(httpMethod, url); if (data != null && httpMethod != RequestBuilder.GET) { String ctype = settings.getContentType(); if (ctype == null) { String type = settings.getDataType(); if (type != null && type.toLowerCase().startsWith("json")) { ctype = "application/json; charset=utf-8"; } else { ctype = FormPanel.ENCODING_URLENCODED; } } requestBuilder.setHeader("Content-Type", ctype); requestBuilder.setRequestData(data); } requestBuilder.setTimeoutMillis(settings.getTimeout()); String user = settings.getUsername(); if (user != null) { requestBuilder.setUser(user); } String password = settings.getPassword(); if (password != null) { requestBuilder.setPassword(password); } Properties headers = settings.getHeaders(); if (headers != null) { for (String headerKey : headers.keys()) { requestBuilder.setHeader(headerKey, headers.getStr(headerKey)); } } return requestBuilder; } private static String resolveUrl(Settings settings, Method httpMethod, String data) { String url = settings.getUrl(); assert url != null : "no url found in settings"; if (httpMethod == RequestBuilder.GET && data != null) { url += (url.contains("?") ? "&" : "?") + data; } return url; } private static String resolveData(Settings settings, Method httpMethod) { String data = settings.getDataString(); if (data == null && settings.getData() != null) { String type = settings.getDataType(); if (type != null && httpMethod == RequestBuilder.POST && type.equalsIgnoreCase("json")) { data = settings.getData().toJsonString(); } else { data = settings.getData().toQueryString(); } } return data; } private static Method resolveHttpMethod(Settings settings) { String method = settings.getType(); if ("get".equalsIgnoreCase(method)) { return RequestBuilder.GET; } return RequestBuilder.POST; } public static void ajax(String url, Function onSuccess, Function onError) { ajax(url, onSuccess, onError, (Settings) null); } public static void ajax(String url, Function onSuccess, Function onError, Settings s) { if (s == null) { s = createSettings(); } s.setUrl(url).setSuccess(onSuccess).setError(onError); ajax(s); } public static void ajax(String url, Properties p) { Settings s = createSettings(); s.load(p); s.setUrl(url); ajax(s); } public static void ajax(String url, Settings settings) { ajax(settings.setUrl(url)); } public static Settings createSettings() { return createSettings($$("")); } public static Settings createSettings(String prop) { return createSettings($$(prop)); } public static Settings createSettings(Properties p) { Settings s = GWT.create(Settings.class); s.load(p); return s; } public static void get(String url, Properties data, final Function onSuccess) { Settings s = createSettings(); s.setUrl(url); s.setDataType("txt"); s.setType("get"); s.setData(data); s.setSuccess(onSuccess); ajax(s); } public static void getJSON(String url, Properties data, final Function onSuccess) { Settings s = createSettings(); s.setUrl(url); s.setDataType("json"); s.setType("post"); s.setData(data); s.setSuccess(onSuccess); ajax(s); } public static void getJSONP(String url, Properties data, Function onSuccess) { Settings s = createSettings(); s.setUrl(url); s.setDataType("jsonp"); s.setType("get"); s.setData(data); s.setSuccess(onSuccess); ajax(s); } public static void getJSONP(String url, Function success, Function error, int timeout) { if (!url.contains("=?") && !url.contains("callback=")) { url += (url.contains("?") ? "&" : "?") + "callback=?"; } url += "&_=" + System.currentTimeMillis(); Element e = $("head").get(0); if (e == null) { e = document.getDocumentElement(); } getJsonpImpl(e, url, null, success, error == null ? success : error, timeout); } public static void post(String url, Properties data, final Function onSuccess) { Settings s = createSettings(); s.setUrl(url); s.setDataType("txt"); s.setType("post"); s.setData(data); s.setSuccess(onSuccess); ajax(s); } protected Ajax(GQuery gq) { super(gq); } public Ajax load(String url, Properties data, final Function onSuccess) { Settings s = createSettings(); final String filter = url.contains(" ") ? url.replaceFirst("^[^\\s]+\\s+", "") : ""; s.setUrl(url.replaceAll("\\s+.+$", "")); s.setDataType("html"); s.setType("get"); s.setData(data); s.setSuccess(new Function() { public void f() { try { // We clean up the returned string to smoothly append it to our document // Note: using '\s\S' instead of '.' because gwt String emulation does // not support java embedded flag expressions (?s) and javascript does // not have multidot flag. String s = getData()[0].toString().replaceAll("<![^>]+>\\s*", "") .replaceAll("</?html[\\s\\S]*?>\\s*", "").replaceAll("<head[\\s\\S]*?</head>\\s*", "") .replaceAll("<script[\\s\\S]*?</script>\\s*", "") .replaceAll("</?body[\\s\\S]*?>\\s*", ""); // We wrap the results in a div s = "<div>" + s + "</div>"; Ajax.this.empty().append(filter.isEmpty() ? $(s) : $(s).find(filter)); if (onSuccess != null) { onSuccess.setElement(Ajax.this.get(0)); onSuccess.f(); } } catch (Exception e) { if (GWT.getUncaughtExceptionHandler() != null) { GWT.getUncaughtExceptionHandler().onUncaughtException(e); } } } }); ajax(s); return this; } private static int callBackCounter = 0; public static native void getJsonpImpl(Element elem, String url, String charset, Function success, Function error, int timeout) /*-{ var fName = "__GQ_cb_" + @com.google.gwt.query.client.plugins.ajax.Ajax::callBackCounter ++; var done = false; $wnd[fName] = function(data) { if (!done) { done = true; $wnd[fName] = null; success.@com.google.gwt.query.client.Function::fe(Ljava/lang/Object;)(data); } } function err() { if (!done) { done = true; $wnd[fName] = null; var func = error ? error : success; func.@com.google.gwt.query.client.Function::fe(Ljava/lang/Object;)(); } } if (timeout) { setTimeout(err, timeout); } url = url.replace(/=\?/g,'=' + fName); var script = document.createElement("script" ); script.async = "async"; if (charset) script.charset = charset; script.src = url; script.onload = script.onreadystatechange = function(evt) { script.onload = script.onreadystatechange = null; elem.removeChild(script); err(); }; elem.insertBefore(script, elem.firstChild); }-*/; }