001// Copyright 2006-2013 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5;
016
017import org.apache.commons.codec.net.URLCodec;
018import org.apache.tapestry5.ioc.annotations.IncompatibleChange;
019import org.apache.tapestry5.services.BaseURLSource;
020import org.apache.tapestry5.services.ContextPathEncoder;
021import org.apache.tapestry5.services.Request;
022
023import java.util.List;
024
025/**
026 * A link is the Tapestry representation of a URL or URI that triggers dynamic behavior. This link is in three parts: a
027 * path portion, an optional anchor, and a set of query parameters. A request for a link will ultimately be recognized
028 * by a {@link org.apache.tapestry5.services.Dispatcher}.
029 * <p/>
030 * Query parameter values are kept separate from the path portion to support encoding those values into hidden form
031 * fields (where appropriate).
032 */
033public interface Link
034{
035    /**
036     * Returns the names of any additional query parameters for the URI. Query parameters store less regular or less
037     * often used values that can not be expressed in the path. They also are used to store, or link to, persistent
038     * state.
039     *
040     * @return list of query parameter names, is alphabetical order
041     */
042    List<String> getParameterNames();
043
044    /**
045     * Returns the value of a specifically named query parameter, or <tt>null</tt> if no such query parameter is stored
046     * in the link.
047     * <p/>
048     * <p>Use this method only when you are sure the parameter has only one value. If the parameter might have more than
049     * one value, use {@link #getParameterValues}.
050     * <p/>
051     * <p>If you use this method with a multivalued parameter, the value returned is equal to the first value in the
052     * array returned by <code>getParameterValues</code>.
053     *
054     * @return a string representing the single value of the named parameter
055     */
056    String getParameterValue(String name);
057
058    /**
059     * Adds a parameter value. The value will be added, as is, to the URL. In many cases, the value should be URL
060     * encoded via {@link URLCodec}.
061     *
062     * @param parameterName
063     *         the name of the parameter to store
064     * @param value
065     *         the value to store, a null or blank value is allowed (as of Tapestry 5.3)
066     * @return this Link, to support method chaining
067     */
068    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
069    Link addParameter(String parameterName, String value);
070
071    /**
072     * Adds a parameter value as a value object; the value object is converted to a string via
073     * {@link ContextPathEncoder#encodeValue(Object)} and the result is added via {@link #addParameter(String, String)}.
074     * The Link object is returned for further configuration.
075     *
076     * @since 5.2.2
077     */
078    Link addParameterValue(String parameterName, Object value);
079
080    /**
081     * Removes a parameter value, which is occasionally useful when transforming a parameter into a portion of
082     * the path.
083     *
084     * @return this Link, to support method chaining
085     * @since 5.2.0
086     */
087    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
088    Link removeParameter(String parameterName);
089
090    /**
091     * Returns the completely unadorned base path. Other methods (such as {@link #toURI()}), may append
092     * an anchor or query parameters.
093     *
094     * @since 5.2.0
095     */
096    String getBasePath();
097
098    /**
099     * Creates a copy of this link that has the same parameters, anchor, and other attributes, but a different
100     * {@linkplain #getBasePath() base path}.
101     *
102     * @return a new Link instance
103     * @since 5.2.0
104     */
105    Link copyWithBasePath(String basePath);
106
107    /**
108     * Returns the URI portion of the link. When the link is created for a form, this will not include query parameters.
109     * This is the same value returned from toString().
110     *
111     * @return the URI, ready to be added as an element attribute
112     */
113    String toURI();
114
115    /**
116     * Returns the link as a redirect URI. The URI includes any query parameters.
117     */
118    String toRedirectURI();
119
120    /**
121     * Returns the link anchor. If this link does not have an anchor, this method returns <tt>null</tt>.
122     *
123     * @return the link anchor
124     */
125    String getAnchor();
126
127    /**
128     * Sets the link anchor. Null and empty anchors will be ignored when building the link URI.
129     *
130     * @param anchor
131     *         the link anchor
132     * @return this Link, to support method chaining
133     */
134    @IncompatibleChange(release = "5.4", details = "changed from void to Link")
135    Link setAnchor(String anchor);
136
137    /**
138     * Returns the absolute URL, which includes the scheme, hostname and possibly port (as per
139     * {@link BaseURLSource#getBaseURL(boolean)}).
140     * By default, the scheme is chosen to match the {@linkplain Request#isSecure() security} of the current request.
141     * <p/>
142     * Note: the semantics of this method changed between Tapestry 5.1 and 5.2. Most code should use toString() or
143     * {@link #toURI()} (which are equivalent) instead.
144     *
145     * @return the complete, qualified URL, including query parameters.
146     */
147    String toAbsoluteURI();
148
149    /**
150     * Returns either the secure or insecure URL, with complete scheme, hostname and possibly port (as per
151     * {@link BaseURLSource#getBaseURL(boolean)}).
152     *
153     * @return the complete, qualified URL, including query parameters.
154     * @since 5.2.2
155     */
156    String toAbsoluteURI(boolean secure);
157
158    /**
159     * Changes the link's security, which can be useful to force a link to be either secure or insecure
160     * when normally it might not be.
161     *
162     * @param newSecurity
163     *         new security value, not null, typically {@link LinkSecurity#FORCE_SECURE} or {@link LinkSecurity#FORCE_INSECURE}
164     * @since 5.3
165     */
166    @IncompatibleChange(release = "5.4", details = "LinkSecurity class moved from internal package to org.apache.tapestry5.")
167    void setSecurity(LinkSecurity newSecurity);
168
169    /**
170     * Returns the current security for this link, which reflects whether the targeted page is itself secure or insecure.
171     *
172     * @since 5.3
173     */
174    @IncompatibleChange(release = "5.4", details = "LinkSecurity class moved from internal package to org.apache.tapestry5.")
175    LinkSecurity getSecurity();
176
177    /**
178     * Returns the parameter values for the given name. Returns null if no such parameter is stored in the link.
179     */
180    String[] getParameterValues(String parameterName);
181
182}