1/*
2 * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package javax.imageio.spi;
27
28import java.util.Locale;
29import javax.imageio.spi.RegisterableService;
30import javax.imageio.spi.ServiceRegistry;
31
32/**
33 * A superinterface for functionality common to all Image I/O service
34 * provider interfaces (SPIs).  For more information on service
35 * provider classes, see the class comment for the
36 * {@code IIORegistry} class.
37 *
38 * @see IIORegistry
39 * @see javax.imageio.spi.ImageReaderSpi
40 * @see javax.imageio.spi.ImageWriterSpi
41 * @see javax.imageio.spi.ImageTranscoderSpi
42 * @see javax.imageio.spi.ImageInputStreamSpi
43 * @see javax.imageio.spi.ImageOutputStreamSpi
44 */
45public abstract class IIOServiceProvider implements RegisterableService {
46
47    /**
48     * A {@code String} to be returned from
49     * {@code getVendorName}, initially {@code null}.
50     * Constructors should set this to a non-{@code null} value.
51     */
52    protected String vendorName;
53
54    /**
55     * A {@code String} to be returned from
56     * {@code getVersion}, initially null.  Constructors should
57     * set this to a non-{@code null} value.
58     */
59    protected String version;
60
61    /**
62     * Constructs an {@code IIOServiceProvider} with a given
63     * vendor name and version identifier.
64     *
65     * @param vendorName the vendor name.
66     * @param version a version identifier.
67     *
68     * @exception IllegalArgumentException if {@code vendorName}
69     * is {@code null}.
70     * @exception IllegalArgumentException if {@code version}
71     * is {@code null}.
72     */
73    public IIOServiceProvider(String vendorName,
74                              String version) {
75        if (vendorName == null) {
76            throw new IllegalArgumentException("vendorName == null!");
77        }
78        if (version == null) {
79            throw new IllegalArgumentException("version == null!");
80        }
81        this.vendorName = vendorName;
82        this.version = version;
83    }
84
85    /**
86     * Constructs a blank {@code IIOServiceProvider}.  It is up
87     * to the subclass to initialize instance variables and/or
88     * override method implementations in order to ensure that the
89     * {@code getVendorName} and {@code getVersion} methods
90     * will return non-{@code null} values.
91     */
92    public IIOServiceProvider() {
93    }
94
95    /**
96     * A callback that will be called exactly once after the Spi class
97     * has been instantiated and registered in a
98     * {@code ServiceRegistry}.  This may be used to verify that
99     * the environment is suitable for this service, for example that
100     * native libraries can be loaded.  If the service cannot function
101     * in the environment where it finds itself, it should deregister
102     * itself from the registry.
103     *
104     * <p> Only the registry should call this method.
105     *
106     * <p> The default implementation does nothing.
107     *
108     * @see ServiceRegistry#registerServiceProvider(Object provider)
109     */
110    public void onRegistration(ServiceRegistry registry,
111                               Class<?> category) {}
112
113    /**
114     * A callback that will be whenever the Spi class has been
115     * deregistered from a {@code ServiceRegistry}.
116     *
117     * <p> Only the registry should call this method.
118     *
119     * <p> The default implementation does nothing.
120     *
121     * @see ServiceRegistry#deregisterServiceProvider(Object provider)
122     */
123    public void onDeregistration(ServiceRegistry registry,
124                                 Class<?> category) {}
125
126    /**
127     * Returns the name of the vendor responsible for creating this
128     * service provider and its associated implementation.  Because
129     * the vendor name may be used to select a service provider,
130     * it is not localized.
131     *
132     * <p> The default implementation returns the value of the
133     * {@code vendorName} instance variable.
134     *
135     * @return a non-{@code null String} containing
136     * the name of the vendor.
137     */
138    public String getVendorName() {
139        return vendorName;
140    }
141
142    /**
143     * Returns a string describing the version
144     * number of this service provider and its associated
145     * implementation.  Because the version may be used by transcoders
146     * to identify the service providers they understand, this method
147     * is not localized.
148     *
149     * <p> The default implementation returns the value of the
150     * {@code version} instance variable.
151     *
152     * @return a non-{@code null String} containing
153     * the version of this service provider.
154     */
155    public String getVersion() {
156        return version;
157    }
158
159    /**
160     * Returns a brief, human-readable description of this service
161     * provider and its associated implementation.  The resulting
162     * string should be localized for the supplied
163     * {@code Locale}, if possible.
164     *
165     * @param locale a {@code Locale} for which the return value
166     * should be localized.
167     *
168     * @return a {@code String} containing a description of this
169     * service provider.
170     */
171    public abstract String getDescription(Locale locale);
172}
173