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