001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.http;
014
015import java.util.List;
016
017import org.apache.commons.codec.net.URLCodec;
018import org.apache.tapestry5.http.services.BaseURLSource;
019import org.apache.tapestry5.http.services.Request;
020import org.apache.tapestry5.ioc.annotations.IncompatibleChange;
021
022/**
023 * A link is the Tapestry representation of a URL or URI that triggers dynamic behavior. This link is in three parts: a
024 * path portion, an optional anchor, and a set of query parameters. A request for a link will ultimately be recognized
025 * by a {@link org.apache.tapestry5.http.services.Dispatcher}.
026 *
027 * Query parameter values are kept separate from the path portion to support encoding those values into hidden form
028 * fields (where appropriate).
029 */
030public interface Link
031{
032    /**
033     * Returns the names of any additional query parameters for the URI. Query parameters store less regular or less
034     * often used values that can not be expressed in the path. They also are used to store, or link to, persistent
035     * state.
036     *
037     * @return list of query parameter names, is alphabetical order
038     */
039    List<String> getParameterNames();
040
041    /**
042     * Returns the value of a specifically named query parameter, or <code>null</code> if no such query parameter is stored
043     * in the link.
044     *
045     * Use this method only when you are sure the parameter has only one value. If the parameter might have more than
046     * one value, use {@link #getParameterValues}.
047     *
048     * If you use this method with a multivalued parameter, the value returned is equal to the first value in the
049     * array returned by <code>getParameterValues</code>.
050     *
051     * @return a string representing the single value of the named parameter
052     */
053    String getParameterValue(String name);
054
055    /**
056     * Adds a parameter value. The value will be added, as is, to the URL. In many cases, the value should be URL
057     * encoded via {@link URLCodec}.
058     *
059     * @param parameterName
060     *         the name of the parameter to store
061     * @param value
062     *         the value to store, a null or blank value is allowed (as of Tapestry 5.3)
063     * @return this Link, to support method chaining
064     */
065    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
066    Link addParameter(String parameterName, String value);
067
068    /**
069     * Adds a parameter value as a value object; the value object is converted to a string via
070     * <a href="http://tapestry.apache.org/current/apidocs/src-html/org/apache/tapestry5/services/ContextPathEncoder.html#line.31">ContextPathEncoder.encodeValue(Object)</a>
071     * from tapestry-core and the result is added via {@link #addParameter(String, String)}.
072     * The Link object is returned for further configuration.
073     *
074     * @since 5.2.2
075     */
076    Link addParameterValue(String parameterName, Object value);
077
078    /**
079     * Removes a parameter value, which is occasionally useful when transforming a parameter into a portion of
080     * the path.
081     *
082     * @return this Link, to support method chaining
083     * @since 5.2.0
084     */
085    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
086    Link removeParameter(String parameterName);
087
088    /**
089     * Returns the completely unadorned base path. Other methods (such as {@link #toURI()}), may append
090     * an anchor or query parameters.
091     *
092     * @since 5.2.0
093     */
094    String getBasePath();
095
096    /**
097     * Creates a copy of this link that has the same parameters, anchor, and other attributes, but a different
098     * {@linkplain #getBasePath() base path}.
099     *
100     * @return a new Link instance
101     * @since 5.2.0
102     */
103    Link copyWithBasePath(String basePath);
104
105    /**
106     * Returns the URI portion of the link. When the link is created for a form, this will not include query parameters.
107     * This is the same value returned from toString().
108     *
109     * @return the URI, ready to be added as an element attribute
110     */
111    String toURI();
112
113    /**
114     * Returns the link as a redirect URI. The URI includes any query parameters.
115     */
116    String toRedirectURI();
117
118    /**
119     * Returns the link anchor. If this link does not have an anchor, this method returns <code>null</code>.
120     *
121     * @return the link anchor
122     */
123    String getAnchor();
124
125    /**
126     * Sets the link anchor. Null and empty anchors will be ignored when building the link URI.
127     *
128     * @param anchor
129     *         the link anchor
130     * @return this Link, to support method chaining
131     */
132    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
133    Link setAnchor(String anchor);
134
135    /**
136     * Returns the absolute URL, which includes the scheme, hostname and possibly port (as per
137     * {@link BaseURLSource#getBaseURL(boolean)}).
138     * By default, the scheme is chosen to match the {@linkplain Request#isSecure() security} of the current request.
139     *
140     * Note: the semantics of this method changed between Tapestry 5.1 and 5.2. Most code should use toString() or
141     * {@link #toURI()} (which are equivalent) instead.
142     *
143     * @return the complete, qualified URL, including query parameters.
144     */
145    String toAbsoluteURI();
146
147    /**
148     * Returns either the secure or insecure URL, with complete scheme, hostname and possibly port (as per
149     * {@link BaseURLSource#getBaseURL(boolean)}).
150     *
151     * @return the complete, qualified URL, including query parameters.
152     * @since 5.2.2
153     */
154    String toAbsoluteURI(boolean secure);
155
156    /**
157     * Changes the link's security, which can be useful to force a link to be either secure or insecure
158     * when normally it might not be.
159     *
160     * @param newSecurity
161     *         new security value, not null, typically {@link LinkSecurity#FORCE_SECURE} or {@link LinkSecurity#FORCE_INSECURE}
162     * @since 5.3
163     */
164    @IncompatibleChange(release = "5.4", details = "LinkSecurity class moved from internal package to org.apache.tapestry5.")
165    void setSecurity(LinkSecurity newSecurity);
166
167    /**
168     * Returns the current security for this link, which reflects whether the targeted page is itself secure or insecure.
169     *
170     * @since 5.3
171     */
172    @IncompatibleChange(release = "5.4", details = "LinkSecurity class moved from internal package to org.apache.tapestry5.")
173    LinkSecurity getSecurity();
174
175    /**
176     * Returns the parameter values for the given name. Returns null if no such parameter is stored in the link.
177     */
178    String[] getParameterValues(String parameterName);
179
180}