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/*
 * Copyright 2009 Google Inc.
 * 
 * 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 com.google.gwt.http.client;

import java.util.HashMap;
import java.util.Map;

/**
 * Utility class to build a URL from components.
 * 
 * TODO(jlabanca): Add a constructor that parses an existing URL
 */
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 listParamMap = new HashMap();

  private String protocol = "http";
  private String host = null;
  private int port = PORT_UNSPECIFIED;
  private String path = null;
  private String hash = null;

  /**
   * 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(URL.encode(protocol)).append("://");

    // http://www.google.com
    if (host != null) {
      url.append(URL.encode(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 entry : listParamMap.entrySet()) {
      for (String val : entry.getValue()) {
        url.append(prefix)
            .append(URL.encodeQueryString(entry.getKey()))
            .append('=');
        if (val != null) {
          // Also encodes +,& etc.
          url.append(URL.encodeQueryString(val));
        }
        prefix = '&';
      }
    }

    // http://www.google.com:80/path/to/file.html?k0=v0&k1=v1#token
    if (hash != null) {
      url.append("#").append(URL.encode(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;
  }

  /**
   * 

* Set a query parameter to a list of values. Each value in the list will be * added as its own key/value pair. * *

*

Example Output

* ?mykey=value0&mykey=value1&mykey=value2 *

* * @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); } } } }




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