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/*
* Copyright 2015 Open Networking Laboratory
*
* 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.
*/
package org.onosproject.ui;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
/**
* Provides convenience methods for dealing with JSON nodes, arrays etc.
*/
public final class JsonUtils {
private static final ObjectMapper MAPPER = new ObjectMapper();
// non-instantiable
private JsonUtils() { }
/**
* Wraps a message payload into an event structure for the given event
* type and sequence ID. Generally, the sequence ID should be a copy of
* the ID from the client request event.
*
* @param type event type
* @param sid sequence ID
* @param payload event payload
* @return the object node representation
*/
public static ObjectNode envelope(String type, long sid, ObjectNode payload) {
ObjectNode event = MAPPER.createObjectNode();
event.put("event", type);
if (sid > 0) {
event.put("sid", sid);
}
event.set("payload", payload);
return event;
}
/**
* Composes a message structure for the given message type and payload.
*
* @param type message type
* @param payload message payload
* @return the object node representation
*/
public static ObjectNode envelope(String type, ObjectNode payload) {
ObjectNode event = MAPPER.createObjectNode();
event.put("event", type);
event.set("payload", payload);
return event;
}
/**
* Returns the event type from the specified event.
* If the node does not have an "event" property, "unknown" is returned.
*
* @param event message event
* @return extracted event type
*/
public static String eventType(ObjectNode event) {
return string(event, "event", "unknown");
}
/**
* Returns the sequence identifier from the specified event, or 0 (zero)
* if the "sid" property does not exist.
*
* @param event message event
* @return extracted sequence identifier
*/
public static long sid(ObjectNode event) {
return number(event, "sid");
}
/**
* Returns the payload from the specified event.
*
* @param event message event
* @return extracted payload object
*/
public static ObjectNode payload(ObjectNode event) {
return (ObjectNode) event.path("payload");
}
/**
* Returns the specified node property as a number.
*
* @param node message event
* @param name property name
* @return property as number
*/
public static long number(ObjectNode node, String name) {
return node.path(name).asLong();
}
/**
* Returns the specified node property as a string.
*
* @param node message event
* @param name property name
* @return property as a string
*/
public static String string(ObjectNode node, String name) {
return node.path(name).asText();
}
/**
* Returns the specified node property as a string, with a default fallback.
*
* @param node object node
* @param name property name
* @param defaultValue fallback value if property is absent
* @return property as a string
*/
public static String string(ObjectNode node, String name, String defaultValue) {
return node.path(name).asText(defaultValue);
}
/**
* Returns the specified node property as an object node.
*
* @param node object node
* @param name property name
* @return property as a node
*/
public static ObjectNode node(ObjectNode node, String name) {
return (ObjectNode) node.path(name);
}
}
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