Java tutorial
package org.sigmah.shared.servlet; /* * #%L * Sigmah * %% * Copyright (C) 2010 - 2016 URD * %% * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program. If not, see * <http://www.gnu.org/licenses/gpl-3.0.html>. * #L% */ import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import org.sigmah.client.inject.Injector; import org.sigmah.client.page.RequestParameter; import org.sigmah.client.util.ClientUtils; import org.sigmah.shared.servlet.ServletConstants.Servlet; import org.sigmah.shared.servlet.ServletConstants.ServletMethod; import com.allen_sauer.gwt.log.client.Log; 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.http.client.URL; /** * Custom servlet request builder. * * @author Denis Colliot (dcolliot@ideia.fr) */ public final class ServletRequestBuilder { /** * Void request callback. */ public static final RequestCallback Void = new RequestCallback() { @Override public void onResponseReceived(Request request, Response response) { // Does nothing. } @Override public void onError(Request request, Throwable exception) { // Does nothing. } }; /** * Default {@link RequestCallback} implementation with default {@code onError()} method. * * @author Denis Colliot (dcolliot@ideia.fr) */ public static abstract class RequestCallbackAdapter implements RequestCallback { /** * {@inheritDoc} */ @Override public void onError(final Request request, final Throwable exception) { // Network error. if (Log.isErrorEnabled()) { Log.error("An unexpected error occured while executing the servlet request.", exception); } } } private final Method requestMethod; private final ServletUrlBuilder urlBuilder; private final Map<String, String> requestAttributes; /** * Builds a new {@code ServletRequestBuilder} with the given parameters. * * @param injector * The client-side injector. * @param requestMethod * request method. * @param servlet * The servlet. * @param method * The servlet method to execute. */ public ServletRequestBuilder(final Injector injector, final Method requestMethod, final Servlet servlet, final ServletMethod method) { this.requestMethod = requestMethod; this.urlBuilder = new ServletUrlBuilder(injector.getAuthenticationProvider(), injector.getPageManager(), servlet, method); this.requestAttributes = new HashMap<String, String>(); this.urlBuilder.addParameter(ServletConstants.AJAX, ClientUtils.toList(true)); } /** * Adds a parameter to the request URL. * * @param key * The parameter key. * @param values * The parameter value(s). * @return the current instance of the builder. */ public ServletRequestBuilder addParameter(final RequestParameter key, final Object... values) { urlBuilder.addParameter(key, values); return this; } /** * Adds a parameter to the request URL. * * @param key * The parameter key. * @param values * The parameter value(s). * @return the current instance of the builder. */ public ServletRequestBuilder addParameter(final RequestParameter key, final List<? extends Object> values) { urlBuilder.addParameter(key, values); return this; } /** * Removes the given parameter {@code key} from the request URL. * * @param key * The parameter key. * @return the current instance of the builder. */ public ServletRequestBuilder removeParameter(final RequestParameter key) { urlBuilder.removeParameter(key); return this; } /** * <p> * Adds a {@code POST} request parameter. * The {@link #requestMethod} must be set to {@link RequestBuilder#POST}. Otherwise, the method does nothing. * </p> * <p> * Empty or {@code null} value is skipped. * {@code String.valueOf(value)} is used for given {@code value}. * </p> * * @param key * The POST parameter key. * @param value * The POST parameter value. * @return The current instance of the builder. */ public ServletRequestBuilder addPostParameter(final RequestParameter key, final Object value) { if (key != null && value != null && isPostMethod()) { requestAttributes.put(key.getRequestName(), String.valueOf(value)); } return this; } /** * Sends the request with its optional parameter(s) (including {@code POST} parameters). * * @param callback * The {@code RequestCallback}. * @throws ServletRequestException * If an error occurs during request call. */ public void send(final RequestCallback callback) throws ServletRequestException { final RequestBuilder requestBuilder = new RequestBuilder(requestMethod, urlBuilder.toString()); requestBuilder.setCallback(callback != null ? callback : Void); final StringBuilder builder = new StringBuilder(); if (ClientUtils.isNotEmpty(requestAttributes)) { final Iterator<String> iterator = requestAttributes.keySet().iterator(); while (iterator.hasNext()) { final String next = iterator.next(); final String attribute = requestAttributes.get(next); if (attribute != null) { builder.append(URL.encodeQueryString(next)); builder.append('='); builder.append(URL.encodeQueryString(attribute)); if (iterator.hasNext()) { builder.append('&'); } } } } if (isPostMethod()) { requestBuilder.setHeader("Content-Type", "application/x-www-form-urlencoded"); requestBuilder.setRequestData(builder.length() > 0 ? builder.toString() : null); } try { requestBuilder.send(); } catch (final RequestException e) { throw new ServletRequestException("Servlet request '" + builder + "' execution fails.", e); } } /** * Returns if the current {@link #requestMethod} is set to {@code POST}. * * @return {@code true} if the current {@link #requestMethod} is set to {@code POST}. */ private boolean isPostMethod() { return RequestBuilder.POST.equals(requestMethod); } /** * Returns the current builder corresponding {@code GET} URL. * If the builder contains {@code POST} parameters, they will <b>not</b> be included in the result. * * @return the current builder corresponding {@code GET} URL. */ @Override public String toString() { return urlBuilder.toString(); } }