001/*
002 * Copyright 2002-2016 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.util;
018
019import java.net.URI;
020import java.net.URISyntaxException;
021import java.util.Collections;
022import java.util.HashMap;
023import java.util.Map;
024
025import org.springframework.util.Assert;
026
027/**
028 * Abstract base class for {@link UriTemplateHandler} implementations.
029 *
030 * <p>Support {@link #setBaseUrl} and {@link #setDefaultUriVariables} properties
031 * that should be relevant regardless of the URI template expand and encode
032 * mechanism used in sub-classes.
033 *
034 * @author Rossen Stoyanchev
035 * @since 4.3
036 */
037public abstract class AbstractUriTemplateHandler implements UriTemplateHandler {
038
039        private String baseUrl;
040
041        private final Map<String, Object> defaultUriVariables = new HashMap<String, Object>();
042
043
044        /**
045         * Configure a base URL to prepend URI templates with. The base URL must
046         * have a scheme and host but may optionally contain a port and a path.
047         * The base URL must be fully expanded and encoded which can be done via
048         * {@link UriComponentsBuilder}.
049         * @param baseUrl the base URL.
050         */
051        public void setBaseUrl(String baseUrl) {
052                if (baseUrl != null) {
053                        UriComponents uriComponents = UriComponentsBuilder.fromUriString(baseUrl).build();
054                        Assert.hasText(uriComponents.getScheme(), "'baseUrl' must have a scheme");
055                        Assert.hasText(uriComponents.getHost(), "'baseUrl' must have a host");
056                        Assert.isNull(uriComponents.getQuery(), "'baseUrl' cannot have a query");
057                        Assert.isNull(uriComponents.getFragment(), "'baseUrl' cannot have a fragment");
058                }
059                this.baseUrl = baseUrl;
060        }
061
062        /**
063         * Return the configured base URL.
064         */
065        public String getBaseUrl() {
066                return this.baseUrl;
067        }
068
069        /**
070         * Configure default URI variable values to use with every expanded URI
071         * template. These default values apply only when expanding with a Map, and
072         * not with an array, where the Map supplied to {@link #expand(String, Map)}
073         * can override the default values.
074         * @param defaultUriVariables the default URI variable values
075         * @since 4.3
076         */
077        public void setDefaultUriVariables(Map<String, ?> defaultUriVariables) {
078                this.defaultUriVariables.clear();
079                if (defaultUriVariables != null) {
080                        this.defaultUriVariables.putAll(defaultUriVariables);
081                }
082        }
083
084        /**
085         * Return a read-only copy of the configured default URI variables.
086         */
087        public Map<String, ?> getDefaultUriVariables() {
088                return Collections.unmodifiableMap(this.defaultUriVariables);
089        }
090
091
092        @Override
093        public URI expand(String uriTemplate, Map<String, ?> uriVariables) {
094                if (!getDefaultUriVariables().isEmpty()) {
095                        Map<String, Object> map = new HashMap<String, Object>();
096                        map.putAll(getDefaultUriVariables());
097                        map.putAll(uriVariables);
098                        uriVariables = map;
099                }
100                URI url = expandInternal(uriTemplate, uriVariables);
101                return insertBaseUrl(url);
102        }
103
104        @Override
105        public URI expand(String uriTemplate, Object... uriVariables) {
106                URI url = expandInternal(uriTemplate, uriVariables);
107                return insertBaseUrl(url);
108        }
109
110
111        /**
112         * Actually expand and encode the URI template.
113         */
114        protected abstract URI expandInternal(String uriTemplate, Map<String, ?> uriVariables);
115
116        /**
117         * Actually expand and encode the URI template.
118         */
119        protected abstract URI expandInternal(String uriTemplate, Object... uriVariables);
120
121
122        /**
123         * Insert a base URL (if configured) unless the given URL has a host already.
124         */
125        private URI insertBaseUrl(URI url) {
126                try {
127                        String baseUrl = getBaseUrl();
128                        if (baseUrl != null && url.getHost() == null) {
129                                url = new URI(baseUrl + url.toString());
130                        }
131                        return url;
132                }
133                catch (URISyntaxException ex) {
134                        throw new IllegalArgumentException("Invalid URL after inserting base URL: " + url, ex);
135                }
136        }
137
138}