Rossen Stoyanchev
8 years ago
41 changed files with 293 additions and 152 deletions
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/* |
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* Copyright 2002-2018 the original author or authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.springframework.core.codec; |
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import java.util.Collections; |
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import java.util.HashMap; |
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import java.util.Map; |
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import org.apache.commons.logging.Log; |
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import org.springframework.lang.Nullable; |
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/** |
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* Constants and convenience methods for working with hints. |
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* |
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* @author Rossen Stoyanchev |
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* @since 5.1 |
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* @see ResourceRegionEncoder#BOUNDARY_STRING_HINT |
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*/ |
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public abstract class Hints { |
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/** |
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* Name of hint exposing a prefix to use for correlating log messages. |
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* @since 5.1 |
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*/ |
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public static final String LOG_PREFIX_HINT = Log.class.getName() + ".PREFIX"; |
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/** |
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* Name of hint for a preferred {@link Log logger} to use. This can be used |
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* by a composite encoder (e.g. multipart requests) to control or suppress |
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* logging by individual part encoders. |
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* @since 5.1 |
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*/ |
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public static final String LOGGER_HINT = Log.class.getName(); |
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/** |
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* Create a map wit a single hint via {@link Collections#singletonMap}. |
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* @param hintName the hint name |
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* @param value the hint value |
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* @return the created map |
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*/ |
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public static Map<String, Object> from(String hintName, Object value) { |
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return Collections.singletonMap(hintName, value); |
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} |
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/** |
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* Return an empty map of hints via {@link Collections#emptyMap()}. |
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* @return the empty map |
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*/ |
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public static Map<String, Object> none() { |
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return Collections.emptyMap(); |
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} |
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/** |
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* Obtain the value for a required hint. |
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* @param hints the hints map |
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* @param hintName the required hint name |
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* @param <T> the hint type to cast to |
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* @return the hint value |
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* @throws IllegalArgumentException if the hint is not found |
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*/ |
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@SuppressWarnings("unchecked") |
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public static <T> T getRequiredHint(@Nullable Map<String, Object> hints, String hintName) { |
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if (hints == null) { |
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throw new IllegalArgumentException("No hints map for required hint '" + hintName + "'"); |
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} |
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T hint = (T) hints.get(hintName); |
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if (hint == null) { |
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throw new IllegalArgumentException("Hints map must contain the hint '" + hintName + "'"); |
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} |
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return hint; |
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} |
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/** |
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* Obtain the hint {@link #LOG_PREFIX_HINT}, if present, or an empty String. |
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* @param hints the hints passed to the encode method |
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* @return the log prefix |
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*/ |
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public static String getLogPrefix(@Nullable Map<String, Object> hints) { |
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return hints != null ? (String) hints.getOrDefault(LOG_PREFIX_HINT, "") : ""; |
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} |
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/** |
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* Obtain the hint {@link #LOGGER_HINT}, if present, or the given logger. |
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* @param hints the hints passed to the encode method |
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* @param defaultLogger the logger to return if a hint is not found |
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* @return the logger to use |
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*/ |
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public static Log getLoggerOrDefault(@Nullable Map<String, Object> hints, Log defaultLogger) { |
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return hints != null ? (Log) hints.getOrDefault(LOGGER_HINT, defaultLogger) : defaultLogger; |
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} |
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/** |
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* Merge two maps of hints, creating and copying into a new map if both have |
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* values, or returning the non-empty map, or an empty map if both are empty. |
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* @param hints1 1st map of hints |
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* @param hints2 2nd map of hints |
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* @return a single map with hints from both |
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*/ |
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public static Map<String, Object> merge(Map<String, Object> hints1, Map<String, Object> hints2) { |
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if (hints1.isEmpty() && hints2.isEmpty()) { |
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return Collections.emptyMap(); |
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} |
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else if (hints2.isEmpty()) { |
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return hints1; |
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} |
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else if (hints1.isEmpty()) { |
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return hints2; |
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} |
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else { |
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Map<String, Object> result = new HashMap<>(hints1.size() + hints2.size()); |
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result.putAll(hints1); |
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result.putAll(hints2); |
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return result; |
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} |
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} |
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/** |
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* Merge a single hint into a map of hints, possibly creating and copying |
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* all hints into a new map, or otherwise if the map of hints is empty, |
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* creating a new single entry map. |
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* @param hints a map of hints to be merge |
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* @param hintName the hint name to merge |
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* @param hintValue the hint value to merge |
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* @return a single map with all hints |
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*/ |
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public static Map<String, Object> merge(Map<String, Object> hints, String hintName, Object hintValue) { |
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if (hints.isEmpty()) { |
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return Collections.singletonMap(hintName, hintValue); |
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} |
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else { |
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Map<String, Object> result = new HashMap<>(hints.size() + 1); |
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result.putAll(hints); |
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result.put(hintName, hintValue); |
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return result; |
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} |
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} |
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} |
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