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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2017-2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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
*
* http://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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.protocol.coders;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.DocumentContext;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.Option;
import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/** JSON Protocol Filter. */
public class JsonProtocolFilter {
/** Default filter to match anything. */
public static final String MATCH_ANY = "[?($ =~ /.*/)]";
/** Logger. */
private static final Logger logger = LoggerFactory.getLogger(JsonProtocolFilter.class);
/** A rule based on a JsonPath expression that is used for filtering. */
private String rule;
/**
* Default constructor (for serialization only).
*/
public JsonProtocolFilter() {
super();
this.setRule(null);
}
/**
* Constructor.
*
* @param rule the JsonPath expression used for the filter rule
* @throws IllegalArgumentException an invalid input has been provided
*/
public JsonProtocolFilter(String rule) {
this.setRule(rule);
}
/**
* Gets the filter expression rule.
*
* @return the filter expression associated with this JsonProtocolFilter
*/
public String getRule() {
return this.rule;
}
/**
* Sets the filter expression rule.
*
* @param rule the JsonPath expression rule
*/
public void setRule(String rule) {
String ruleExpression = rule;
if (rule == null || rule.isEmpty()) {
ruleExpression = MATCH_ANY;
}
this.rule = ruleExpression;
}
/**
* Accepts a JSON message if there is a match on the filter expression.
*
* @return true if a match is found or the rule uses the match any policy, false otherwise
*/
public boolean accept(String json) {
if (MATCH_ANY.equals(this.rule)) {
return true;
}
return !filter(json).isEmpty();
}
/**
* Finds a field based on a path or a subset of the JSON if using an expression.
*
* @param json the JSON string to be parsed
* @return a list of strings that match the expression
*/
public List<String> filter(String json) {
return filter(json, this.rule);
}
/**
* Finds all occurrences of a field in a JSON document based on the JsonPath
* expression.
*
* @param json the JSON string to be parsed
* @param expression the JsonPath expression
* @return a list of matches from the JSON document
*/
public static List<String> filter(String json, String expression) {
if (json == null || json.isEmpty()) {
throw new IllegalArgumentException("a json string must be provided");
}
if (expression == null || expression.isEmpty()) {
throw new IllegalArgumentException("an expression must be provided");
}
Configuration conf = Configuration.defaultConfiguration().addOptions(Option.ALWAYS_RETURN_LIST);
DocumentContext document = JsonPath.using(conf).parse(json);
List<String> matches = new ArrayList<>();
try {
matches = document.read(expression);
} catch (Exception e) {
logger.error("JsonPath couldn't read {} because of {}", expression, e.getMessage(), e);
}
if (matches.isEmpty()) {
logger.warn("Could not find any matches for rule {} in json {}", expression, json);
}
return matches;
}
}
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