Java tutorial
/** * Copyright (C) 2011 Brian Ferris <bdferris@onebusaway.org> * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.onebusaway.presentation.client; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import com.google.gwt.http.client.URL; import com.google.gwt.user.client.Window.Location; /** * Utility class to build a URL from components. * * TODO(jlabanca): Add a constructor that parses an existing URL * * Note that this class was copied verbatim from the * com.google.gwt.http.client.URLBuilder in GWT, but modified to fix bugs with * escaping (especially param values that included a & character) */ public class UrlBuilder { /** * The port to use when no port should be specified. */ public static final int PORT_UNSPECIFIED = Integer.MIN_VALUE; /** * A mapping of query parameters to their values. */ private Map<String, String[]> listParamMap = new HashMap<String, String[]>(); private String protocol = "http"; private String host = null; private int port = PORT_UNSPECIFIED; private String path = null; private String hash = null; public static UrlBuilder createFromLocation() { UrlBuilder builder = new UrlBuilder(); builder.setProtocol(Location.getProtocol()); builder.setHost(Location.getHost()); String path = Location.getPath(); if (path != null && path.length() > 0) { builder.setPath(path); } String hash = Location.getHash(); if (hash != null && hash.length() > 0) { builder.setHash(hash); } String port = Location.getPort(); if (port != null && port.length() > 0) { builder.setPort(Integer.parseInt(port)); } // Add query parameters. Map<String, List<String>> params = Location.getParameterMap(); for (Map.Entry<String, List<String>> entry : params.entrySet()) { List<String> values = new ArrayList<String>(entry.getValue()); builder.setParameter(entry.getKey(), values.toArray(new String[values.size()])); } return builder; } /** * Build the URL and return it as an encoded string. * * @return the encoded URL string */ public String buildString() { StringBuilder url = new StringBuilder(); // http:// url.append(protocol).append("://"); // http://www.google.com if (host != null) { url.append(host); } // http://www.google.com:80 if (port != PORT_UNSPECIFIED) { url.append(":").append(port); } // http://www.google.com:80/path/to/file.html if (path != null && !"".equals(path)) { url.append("/").append(URL.encode(path)); } // Generate the query string. // http://www.google.com:80/path/to/file.html?k0=v0&k1=v1 char prefix = '?'; for (Map.Entry<String, String[]> entry : listParamMap.entrySet()) { String key = URL.encodeComponent(entry.getKey()); for (String val : entry.getValue()) { url.append(prefix).append(key).append('='); if (val != null) { url.append(URL.encodeComponent(val)); } prefix = '&'; } } // http://www.google.com:80/path/to/file.html?k0=v0&k1=v1#token if (hash != null) { url.append("#").append(hash); } return url.toString(); } /** * Remove a query parameter from the map. * * @param name the parameter name */ public UrlBuilder removeParameter(String name) { listParamMap.remove(name); return this; } /** * Set the hash portion of the location (ex. myAnchor or #myAnchor). * * @param hash the hash */ public UrlBuilder setHash(String hash) { if (hash != null && hash.startsWith("#")) { hash = hash.substring(1); } this.hash = hash; return this; } /** * Set the host portion of the location (ex. google.com). You can also specify * the port in this method (ex. localhost:8888). * * @param host the host */ public UrlBuilder setHost(String host) { // Extract the port from the host. if (host != null && host.contains(":")) { String[] parts = host.split(":"); if (parts.length > 2) { throw new IllegalArgumentException("Host contains more than one colon: " + host); } try { setPort(Integer.parseInt(parts[1])); } catch (NumberFormatException e) { throw new IllegalArgumentException("Could not parse port out of host: " + host); } host = parts[0]; } this.host = host; return this; } /** * <p> * Set a query parameter to a list of values. Each value in the list will be * added as its own key/value pair. * * <p> * <h3>Example Output</h3> * <code>?mykey=value0&mykey=value1&mykey=value2</code> * </p> * * @param key the key * @param values the list of values */ public UrlBuilder setParameter(String key, String... values) { assertNotNullOrEmpty(key, "Key cannot be null or empty", false); assertNotNull(values, "Values cannot null. Try using removeParameter instead."); if (values.length == 0) { throw new IllegalArgumentException("Values cannot be empty. Try using removeParameter instead."); } listParamMap.put(key, values); return this; } /** * Set the path portion of the location (ex. path/to/file.html). * * @param path the path */ public UrlBuilder setPath(String path) { if (path != null && path.startsWith("/")) { path = path.substring(1); } this.path = path; return this; } /** * Set the port to connect to. * * @param port the port, or {@link #PORT_UNSPECIFIED} */ public UrlBuilder setPort(int port) { this.port = port; return this; } /** * Set the protocol portion of the location (ex. http). * * @param protocol the protocol */ public UrlBuilder setProtocol(String protocol) { assertNotNull(protocol, "Protocol cannot be null"); if (protocol.endsWith("://")) { protocol = protocol.substring(0, protocol.length() - 3); } else if (protocol.endsWith(":/")) { protocol = protocol.substring(0, protocol.length() - 2); } else if (protocol.endsWith(":")) { protocol = protocol.substring(0, protocol.length() - 1); } if (protocol.contains(":")) { throw new IllegalArgumentException("Invalid protocol: " + protocol); } assertNotNullOrEmpty(protocol, "Protocol cannot be empty", false); this.protocol = protocol; return this; } /** * Assert that the value is not null. * * @param value the value * @param message the message to include with any exceptions * @throws IllegalArgumentException if value is null */ private void assertNotNull(Object value, String message) throws IllegalArgumentException { if (value == null) { throw new IllegalArgumentException(message); } } /** * Assert that the value is not null or empty. * * @param value the value * @param message the message to include with any exceptions * @param isState if true, throw a state exception instead * @throws IllegalArgumentException if value is null * @throws IllegalStateException if value is null and isState is true */ private void assertNotNullOrEmpty(String value, String message, boolean isState) throws IllegalArgumentException { if (value == null || value.length() == 0) { if (isState) { throw new IllegalStateException(message); } else { throw new IllegalArgumentException(message); } } } }