com.thorstenmarx.modules.api.message.Message Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of modules-api Show documentation
Modules is a tiny module framework for java.
There is a newer version: 2.8.0
/**
 * ModuleManager
 * Copyright (C) 2016  ThorstenMarx ([email protected])
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 com.thorstenmarx.modules.api.message;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;

/**
 * MUTABLE message object that passed from publisher to consumer.
 * Be aware of possible message values mutability, do not try to edit this values in consumer.
 * Each message may contain key-value(object) map.
 *
 * Keep in mind that Messageis not serializable because it should be used only in one active instance.
 */
public class Message {

    private final String type;

    private final Map properties = new HashMap<>(8);

    private boolean locked;

    /**
     * Create message with appropriate type.
     *
     * @param type Message type, message bus will use type while choosing appropriate consumers.
     */
    public Message(String type) {
        this.type = Objects.requireNonNull(type);
    }

    /**
     * Create message with provided properties.
     *
     * @param type Message type, message bus will use type while choosing appropriate consumers.'
     * @param properties Message properties
     */
    public Message(String type, Map properties) {
        this.type = Objects.requireNonNull(type);;
        this.properties.putAll(Objects.requireNonNull(properties));
    }

    /**
     * Return message type.
     * Message bus will use type while choosing appropriate consumers.
	 * @return 
     */
    public String getType() {
        return type;
    }

    protected void lock() {
        this.locked = true;
    }

    private void isLocked() {
        if (locked) {
            throw new UnsupportedOperationException("You can not call any setters on "
                + getClass().getSimpleName() + " instance after message was published.");
        }
    }

    /**
     * Return true if message has any properties (key-value maps is not empty).
	 * @return 
     */
    public boolean hasProperties() {
        return properties.isEmpty();
    }

    /**
     * Return all keys associated with key-value properties of current message.
	 * @return 
     */
    public Collection getKeys() {
        return properties.keySet();
    }

    /**
     * Associate property value with message.
     *
     * @param key Property key
     * @param value Property value
     * @throws UnsupportedOperationException If this method will be called during message processing
     */
    public void set(String key, Object value) throws UnsupportedOperationException {
        isLocked();
        properties.put(key, value);
    }

    /**
     * Return message property value casted to class if any.
     *
     * @param key Property key in map
     * @param cls Expected value class
     * @return Result will be empty if value does not exist or wrong class to cast
     */
    public  Optional getValue(String key, Class cls) {
        return Optional.ofNullable(get(key, cls));
    }

    /**
     * Return message property value casted to class if any.
     *
     * @param key Property key in map
     * @param cls Expected value class
     * @return Will return matched value or null (if value does not exist or wrong class)
     */
    public  T get(String key, Class cls) {
        Object val = properties.get(key);
        if (val == null) {
            return null;
        }

        if (cls.isInstance(val)) {
            return cls.cast(val);
        }
        return null;
    }

    /**
     * Return message property value casted to class or default value.
     *
     * @param key Property key in map
     * @param cls Expected value class
     * @return Will return matched value or null (if value does not exist or wrong class)
     *
     */
    public  T getOr(String key, Class cls, T defaultValue) {
        T val = get(key, cls);
        return val == null ? defaultValue : val;
    }

    /**
     * Return string representation of value using toSting method.
     *
     * @param key Property key
     * @return String or null if not value
     */
    public String getString(String key) {
        Object val = properties.get(key);

        return val == null ? null : val.toString();
    }

    /**
     * Return string representation of value using toSting method or default String.
     *
     * @param key Property key
	 * @param defaultValue
     * @return String or default value
     */
    public String getStringOr(String key, String defaultValue) {
        String str = getString(key);
        return str == null ? defaultValue : str;
    }
}