org.springframework.cloud.function.adapter.aws.SpringFunctionInitializer.java Source code

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Here is the source code for org.springframework.cloud.function.adapter.aws.SpringFunctionInitializer.java

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/*
 * Copyright 2017 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.function.adapter.aws;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.function.context.FunctionInspector;
import org.springframework.cloud.function.registry.FunctionCatalog;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.util.ClassUtils;
import reactor.core.publisher.Flux;

import java.io.Closeable;
import java.io.InputStream;
import java.net.URL;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.jar.Manifest;

/**
 * @author Dave Syer
 */
public class SpringFunctionInitializer implements Closeable {

    private static Log logger = LogFactory.getLog(SpringFunctionInitializer.class);

    private final Class<?> configurationClass;

    private Function<Flux<?>, Flux<?>> function;

    private Consumer<Flux<?>> consumer;

    private Supplier<Flux<?>> supplier;

    private AtomicBoolean initialized = new AtomicBoolean();

    @Autowired(required = false)
    private FunctionInspector inspector;

    @Autowired(required = false)
    private FunctionCatalog catalog;

    private String name;

    private ConfigurableApplicationContext context;

    public SpringFunctionInitializer(Class<?> configurationClass) {
        this.configurationClass = configurationClass;
    }

    public SpringFunctionInitializer() {
        this(getStartClass());
    }

    @Override
    public void close() {
        if (this.context != null) {
            this.context.close();
        }
    }

    @SuppressWarnings("unchecked")
    protected void initialize() {
        if (!this.initialized.compareAndSet(false, true)) {
            return;
        }
        logger.info("Initializing: " + configurationClass);
        SpringApplicationBuilder builder = new SpringApplicationBuilder(configurationClass);
        ConfigurableApplicationContext context = builder.web(false).run();
        context.getAutowireCapableBeanFactory().autowireBean(this);
        String name = context.getEnvironment().getProperty("function.name");
        boolean defaultName = false;
        if (name == null) {
            name = "function";
            defaultName = true;
        }
        if (this.catalog == null) {
            this.function = context.getBean(name, Function.class);
        } else {
            this.function = this.catalog.lookupFunction(name);
            this.name = name;
            if (this.function == null) {
                if (defaultName) {
                    name = "consumer";
                }
                this.consumer = this.catalog.lookupConsumer(name);
                this.name = name;
                if (this.consumer == null) {
                    if (defaultName) {
                        name = "supplier";
                    }
                    this.supplier = this.catalog.lookupSupplier(name);
                    this.name = name;
                }
            }
        }
        this.context = context;
    }

    protected Class<?> getInputType() {
        if (inspector != null) {
            return inspector.getInputType(this.name);
        }
        return Object.class;
    }

    protected Flux<?> apply(Flux<?> input) {
        if (this.function != null) {
            return function.apply(input);
        }
        if (this.consumer != null) {
            this.consumer.accept(input);
            return Flux.empty();
        }
        if (this.supplier != null) {
            return this.supplier.get();
        }
        throw new IllegalStateException("No function defined");
    }

    private static Class<?> getStartClass() {
        ClassLoader classLoader = SpringFunctionInitializer.class.getClassLoader();
        if (System.getenv("MAIN_CLASS") != null) {
            return ClassUtils.resolveClassName(System.getenv("MAIN_CLASS"), classLoader);
        }
        try {
            Class<?> result = getStartClass(Collections.list(classLoader.getResources("META-INF/MANIFEST.MF")));
            if (result == null) {
                result = getStartClass(Collections.list(classLoader.getResources("meta-inf/manifest.mf")));
            }
            logger.info("Main class: " + result);
            return result;
        } catch (Exception ex) {
            logger.error("Failed to find main class", ex);
            return null;
        }
    }

    private static Class<?> getStartClass(List<URL> list) {
        logger.info("Searching manifests: " + list);
        for (URL url : list) {
            try {
                logger.info("Searching manifest: " + url);
                InputStream inputStream = url.openStream();
                try {
                    Manifest manifest = new Manifest(inputStream);
                    String startClass = manifest.getMainAttributes().getValue("Start-Class");
                    if (startClass != null) {
                        return ClassUtils.forName(startClass, SpringFunctionInitializer.class.getClassLoader());
                    }
                } finally {
                    inputStream.close();
                }
            } catch (Exception ex) {
            }
        }
        return null;
    }

}