org.springframework.cloud.stream.binder.DefaultBinding.java Source code

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Here is the source code for org.springframework.cloud.stream.binder.DefaultBinding.java

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/*
 * Copyright 2013-2018 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
 *
 *      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.springframework.cloud.stream.binder;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.context.Lifecycle;
import org.springframework.integration.endpoint.Pausable;
import org.springframework.integration.support.context.NamedComponent;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * Default implementation for a {@link Binding}.
 * @author Jennifer Hickey
 * @author Mark Fisher
 * @author Gary Russell
 * @author Marius Bogoevici
 * @author Oleg Zhurakousky
 *
 * @see org.springframework.cloud.stream.annotation.EnableBinding
 */
@JsonPropertyOrder({ "name", "group", "pausable", "state" })
@JsonIgnoreProperties("running")
public class DefaultBinding<T> implements Binding<T> {

    private final Log logger = LogFactory.getLog(this.getClass().getName());

    protected final String name;

    protected final String group;

    protected final T target;

    protected final Lifecycle lifecycle;

    private boolean paused;

    private boolean restartable;

    /**
     * Creates an instance that associates a given name, group and binding target with an
     * optional {@link Lifecycle} component, which will be stopped during unbinding.
     *
     * @param name the name of the binding target
     * @param group the group (only for input targets)
     * @param target the binding target
     * @param lifecycle {@link Lifecycle} that runs while the binding is active and will be stopped during unbinding
     */
    public DefaultBinding(String name, String group, T target, Lifecycle lifecycle) {
        Assert.notNull(target, "target must not be null");
        this.name = name;
        this.group = group;
        this.target = target;
        this.lifecycle = lifecycle;
        this.restartable = StringUtils.hasText(group);
    }

    public DefaultBinding(String name, T target, Lifecycle lifecycle) {
        this(name, null, target, lifecycle);
        this.restartable = true;
    }

    public String getName() {
        return this.name;
    }

    public String getGroup() {
        return this.group;
    }

    public String getState() {
        String state = "N/A";
        if (this.lifecycle != null) {
            if (isPausable()) {
                state = this.paused ? "paused" : this.getRunningState();
            } else {
                state = this.getRunningState();
            }
        }
        return state;
    }

    public boolean isRunning() {
        return this.lifecycle != null && this.lifecycle.isRunning();
    }

    public boolean isPausable() {
        return this.lifecycle instanceof Pausable;
    }

    @Override
    public final synchronized void start() {
        if (!this.isRunning()) {
            if (this.lifecycle != null && this.restartable) {
                this.lifecycle.start();
            } else {
                logger.warn("Can not re-bind an anonymous binding");
            }
        }
    }

    @Override
    public final synchronized void stop() {
        if (this.isRunning()) {
            this.lifecycle.stop();
        }
    }

    @Override
    public final synchronized void pause() {
        if (this.lifecycle instanceof Pausable) {
            ((Pausable) this.lifecycle).pause();
            this.paused = true;
        } else {
            logger.warn("Attempted to pause a component that does not support Pausable " + this.lifecycle);
        }
    }

    @Override
    public final synchronized void resume() {
        if (this.lifecycle instanceof Pausable) {
            ((Pausable) this.lifecycle).resume();
            this.paused = false;
        } else {
            logger.warn("Attempted to resume a component that does not support Pausable " + this.lifecycle);
        }
    }

    @Override
    public final void unbind() {
        this.stop();
        afterUnbind();
    }

    Lifecycle getEndpoint() {
        return this.lifecycle;
    }

    @Override
    public String toString() {
        return " Binding [name=" + this.name + ", target=" + this.target + ", lifecycle="
                + ((this.lifecycle instanceof NamedComponent) ? ((NamedComponent) this.lifecycle).getComponentName()
                        : ObjectUtils.nullSafeToString(this.lifecycle))
                + "]";
    }

    /**
     * Listener method that executes after unbinding. Subclasses can implement their own
     * behaviour on unbinding by overriding this method.
     */
    protected void afterUnbind() {
    }

    private String getRunningState() {
        return isRunning() ? "running" : "stopped";
    }
}