org.apache.james.protocols.lib.ProtocolHandlerChainImpl.java Source code

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Here is the source code for org.apache.james.protocols.lib.ProtocolHandlerChainImpl.java

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 * 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   *
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package org.apache.james.protocols.lib;

import org.apache.commons.configuration.CombinedConfiguration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.ConfigurationUtils;
import org.apache.commons.configuration.DefaultConfigurationBuilder;
import org.apache.commons.configuration.HierarchicalConfiguration;
import org.apache.james.protocols.api.handler.ExtensibleHandler;
import org.apache.james.protocols.api.handler.ProtocolHandler;
import org.apache.james.protocols.api.handler.ProtocolHandlerChain;
import org.apache.james.protocols.api.handler.WiringException;
import org.apache.james.protocols.lib.handler.HandlersPackage;
import org.apache.james.protocols.lib.handler.ProtocolHandlerLoader;

import java.util.LinkedList;
import java.util.List;

public class ProtocolHandlerChainImpl implements ProtocolHandlerChain {

    private final ProtocolHandlerLoader loader;
    private final HierarchicalConfiguration handlerchainConfig;
    private final String jmxName;
    private final String coreHandlersPackage;
    private final String jmxHandlersPackage;
    private final List<Object> handlers = new LinkedList<Object>();

    public ProtocolHandlerChainImpl(ProtocolHandlerLoader loader, HierarchicalConfiguration handlerchainConfig,
            String jmxName, Class<? extends HandlersPackage> coreHandlersPackage,
            Class<? extends HandlersPackage> jmxHandlersPackage) {
        this.loader = loader;
        this.handlerchainConfig = handlerchainConfig;
        this.jmxName = jmxName;
        this.coreHandlersPackage = coreHandlersPackage.getName();
        this.jmxHandlersPackage = jmxHandlersPackage.getName();
    }

    public void init() throws Exception {
        List<org.apache.commons.configuration.HierarchicalConfiguration> children = handlerchainConfig
                .configurationsAt("handler");

        // check if the coreHandlersPackage was specified in the config, if
        // not add the default
        if (handlerchainConfig.getString("[@coreHandlersPackage]") == null)
            handlerchainConfig.addProperty("[@coreHandlersPackage]", coreHandlersPackage);

        String coreHandlersPackage = handlerchainConfig.getString("[@coreHandlersPackage]");

        if (handlerchainConfig.getString("[@jmxHandlersPackage]") == null)
            handlerchainConfig.addProperty("[@jmxHandlersPackage]", jmxHandlersPackage);

        String jmxHandlersPackage = handlerchainConfig.getString("[@jmxHandlersPackage]");

        HandlersPackage handlersPackage = (HandlersPackage) loader.load(coreHandlersPackage,
                addHandler(coreHandlersPackage));
        registerHandlersPackage(handlersPackage, null, children);

        if (handlerchainConfig.getBoolean("[@enableJmx]", true)) {
            DefaultConfigurationBuilder builder = new DefaultConfigurationBuilder();
            builder.addProperty("jmxName", jmxName);
            HandlersPackage jmxPackage = (HandlersPackage) loader.load(jmxHandlersPackage,
                    addHandler(jmxHandlersPackage));

            registerHandlersPackage(jmxPackage, builder, children);
        }

        for (HierarchicalConfiguration hConf : children) {
            String className = hConf.getString("[@class]", null);
            if (className != null) {
                handlers.add(loader.load(className, hConf));
            } else {
                throw new ConfigurationException(
                        "Missing @class attribute in configuration: " + ConfigurationUtils.toString(hConf));
            }
        }
        wireExtensibleHandlers();

    }

    private void wireExtensibleHandlers() throws WiringException {
        LinkedList<ExtensibleHandler> eHandlers = getHandlers(ExtensibleHandler.class);
        for (ExtensibleHandler extensibleHandler : eHandlers) {
            final List<Class<?>> markerInterfaces = extensibleHandler.getMarkerInterfaces();
            for (Class<?> markerInterface : markerInterfaces) {
                final List<?> extensions = getHandlers(markerInterface);
                // ok now time for try the wiring
                extensibleHandler.wireExtensions(markerInterface, extensions);
            }
        }

    }

    private void registerHandlersPackage(HandlersPackage handlersPackage, HierarchicalConfiguration handlerConfig,
            List<HierarchicalConfiguration> children) throws ConfigurationException {
        List<String> c = handlersPackage.getHandlers();

        for (String cName : c) {
            try {
                CombinedConfiguration conf = new CombinedConfiguration();
                HierarchicalConfiguration cmdConf = addHandler(cName);
                conf.addConfiguration(cmdConf);
                if (handlerConfig != null) {
                    conf.addConfiguration(handlerConfig);
                }
                children.add(conf);
            } catch (ConfigurationException e) {
                throw new ConfigurationException("Unable to create configuration for handler " + cName, e);
            }
        }
    }

    /**
     * Return a DefaultConfiguration build on the given command name and
     * classname.
     *
     * @param className The class name
     * @return DefaultConfiguration
     * @throws ConfigurationException
     */
    private HierarchicalConfiguration addHandler(String className) throws ConfigurationException {
        HierarchicalConfiguration hConf = new DefaultConfigurationBuilder();
        hConf.addProperty("[@class]", className);
        return hConf;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> LinkedList<T> getHandlers(Class<T> type) {
        LinkedList<T> hList = new LinkedList<T>();

        for (Object h : handlers) {
            if (type.isInstance(h)) {
                hList.add((T) h);

            }
        }
        return hList;
    }

    /**
     * Destroy all loaded {@link ProtocolHandler}
     */
    @Override
    public void destroy() {
        LinkedList<ProtocolHandler> lHandlers = getHandlers(ProtocolHandler.class);
        for (ProtocolHandler handler : lHandlers) {
            handler.destroy();
        }
    }
}