org.springframework.integration.endpoint.MethodInvokingMessageSource.java Source code

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Here is the source code for org.springframework.integration.endpoint.MethodInvokingMessageSource.java

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/*
 * Copyright 2002-2019 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.integration.endpoint;

import java.lang.reflect.Method;

import org.springframework.context.Lifecycle;
import org.springframework.messaging.MessagingException;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;

/**
 * A {@link org.springframework.integration.core.MessageSource} implementation that
 * invokes a no-argument method so that its return value may be sent to a channel.
 *
 * @author Mark Fisher
 * @author Gary Russell
 * @author Artem Bilan
 */
public class MethodInvokingMessageSource extends AbstractMessageSource<Object> implements Lifecycle {

    private volatile Object object;

    private volatile Method method;

    private volatile String methodName;

    private volatile boolean initialized;

    private final Object initializationMonitor = new Object();

    public void setObject(Object object) {
        Assert.notNull(object, "'object' must not be null");
        this.object = object;
    }

    public void setMethod(Method method) {
        Assert.notNull(method, "'method' must not be null");
        this.method = method;
    }

    public void setMethodName(String methodName) {
        Assert.notNull(methodName, "'methodName' must not be null");
        this.methodName = methodName;
    }

    @Override
    public String getComponentType() {
        return "inbound-channel-adapter";
    }

    @Override
    protected void onInit() {
        synchronized (this.initializationMonitor) {
            if (this.initialized) {
                return;
            }
            Assert.notNull(this.object, "object is required");
            Assert.isTrue(this.method != null || this.methodName != null, "method or methodName is required");
            if (this.method == null) {
                this.method = ReflectionUtils.findMethod(this.object.getClass(), this.methodName);
                Assert.notNull(this.method,
                        "no such method '" + this.methodName + "' is available on " + this.object.getClass());
            }
            Assert.isTrue(!void.class.equals(this.method.getReturnType()),
                    "invalid MessageSource method '" + this.method.getName() + "', a non-void return is required");
            this.method.setAccessible(true);
            this.initialized = true;
        }
    }

    @Override
    public void start() {
        if (this.object instanceof Lifecycle) {
            ((Lifecycle) this.object).start();
        }
    }

    @Override
    public void stop() {
        if (this.object instanceof Lifecycle) {
            ((Lifecycle) this.object).stop();
        }
    }

    @Override
    public boolean isRunning() {
        return !(this.object instanceof Lifecycle) || ((Lifecycle) this.object).isRunning();
    }

    @Override
    protected Object doReceive() {
        try {
            if (!this.initialized) {
                this.afterPropertiesSet();
            }
            return ReflectionUtils.invokeMethod(this.method, this.object);
        } catch (Exception e) {
            throw new MessagingException("Failed to invoke method", e);
        }
    }

}