defaultconfiguration.java

一个很好实用的工作流OSWORKFLOW开发例子.有着非常优秀的灵活性.

/*
 * Copyright (c) 2002-2003 by OpenSymphony
 * All rights reserved.
 */
package com.opensymphony.workflow.config;

import com.opensymphony.workflow.FactoryException;
import com.opensymphony.workflow.StoreException;
import com.opensymphony.workflow.loader.*;
import com.opensymphony.workflow.loader.ClassLoaderUtil;
import com.opensymphony.workflow.spi.WorkflowStore;
import com.opensymphony.workflow.util.DefaultVariableResolver;
import com.opensymphony.workflow.util.VariableResolver;

import org.w3c.dom.*;

import java.io.InputStream;
import java.io.Serializable;

import java.net.URL;

import java.util.*;

import javax.xml.parsers.*;


/**
 * Default implementation for a configuration object.
 * This configuration object is passed to the {@link com.opensymphony.workflow.Workflow#setConfiguration(Configuration)}
 * method. If the configuration is not initialized, the {@link #load(java.net.URL)} method will be called by
 * the workflow. Alternatively, the caller can explicitly load the configuration by calling that method before
 * calling {@link com.opensymphony.workflow.Workflow#setConfiguration(Configuration)}.
 * <p>
 * The loading behaviour comes into play when specifying a configuration remotely, for example in an EJB
 * environment. It might be desirable to ensure that the configuration is loaded from within the EJB server,
 * rather than in the calling client.
 *
 * @author Hani Suleiman
 * @version $Revision: 1.14 $
 */
public class DefaultConfiguration implements Configuration, Serializable {
    //~ Static fields/initializers /////////////////////////////////////////////

    private static final long serialVersionUID = 4120889092947132961L;
    public static DefaultConfiguration INSTANCE = new DefaultConfiguration();

    //~ Instance fields ////////////////////////////////////////////////////////

    private Map persistenceArgs = new HashMap();
    private String persistenceClass;
    private WorkflowFactory factory = new URLWorkflowFactory();
    private transient WorkflowStore store = null;
    private VariableResolver variableResolver = new DefaultVariableResolver();
    private boolean initialized;

    //~ Methods ////////////////////////////////////////////////////////////////

    public boolean isInitialized() {
        return initialized;
    }

    public boolean isModifiable(String name) {
        return factory.isModifiable(name);
    }

    public void setPersistence(String persistence) {
        persistenceClass = persistence;
    }

    public String getPersistence() {
        return persistenceClass;
    }

    public Map getPersistenceArgs() {
        return persistenceArgs;
    }

    public VariableResolver getVariableResolver() {
        return variableResolver;
    }

    public WorkflowDescriptor getWorkflow(String name) throws FactoryException {
        WorkflowDescriptor workflow = factory.getWorkflow(name);

        if (workflow == null) {
            throw new FactoryException("Unknown workflow name");
        }

        return workflow;
    }

    public String[] getWorkflowNames() throws FactoryException {
        return factory.getWorkflowNames();
    }

    public WorkflowStore getWorkflowStore() throws StoreException {
        if (store == null) {
            String clazz = getPersistence();

            try {
                store = (WorkflowStore) Class.forName(clazz).newInstance();
            } catch (Exception ex) {
                throw new StoreException("Error creating store", ex);
            }

            store.init(getPersistenceArgs());
        }

        return store;
    }

    public void load(URL url) throws FactoryException {
        InputStream is = getInputStream(url);

        if (is == null) {
            throw new FactoryException("Cannot find osworkflow.xml configuration file in classpath or in META-INF");
        }

        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setNamespaceAware(true);

            DocumentBuilder db;

            try {
                db = dbf.newDocumentBuilder();
            } catch (ParserConfigurationException e) {
                throw new FactoryException("Error creating document builder", e);
            }

            Document doc = db.parse(is);

            Element root = (Element) doc.getElementsByTagName("osworkflow").item(0);
            Element p = XMLUtil.getChildElement(root, "persistence");
            Element resolver = XMLUtil.getChildElement(root, "resolver");
            Element factoryElement = XMLUtil.getChildElement(root, "factory");

            if (resolver != null) {
                String resolverClass = resolver.getAttribute("class");

                if (resolverClass != null) {
                    variableResolver = (VariableResolver) ClassLoaderUtil.loadClass(resolverClass, getClass()).newInstance();
                }
            }

            persistenceClass = p.getAttribute("class");

            List args = XMLUtil.getChildElements(p, "property");

            //persistenceArgs = new HashMap();
            for (int i = 0; i < args.size(); i++) {
                Element e = (Element) args.get(i);
                persistenceArgs.put(e.getAttribute("key"), e.getAttribute("value"));
            }

            if (factoryElement != null) {
                String clazz = null;

                try {
                    clazz = factoryElement.getAttribute("class");

                    if (clazz == null) {
                        throw new FactoryException("factory does not specify a class attribute");
                    }

                    factory = (WorkflowFactory) ClassLoaderUtil.loadClass(clazz, getClass()).newInstance();

                    Properties properties = new Properties();
                    List props = XMLUtil.getChildElements(factoryElement, "property");

                    for (int i = 0; i < props.size(); i++) {
                        Element e = (Element) props.get(i);
                        properties.setProperty(e.getAttribute("key"), e.getAttribute("value"));
                    }

                    factory.init(properties);
                    factory.initDone();
                } catch (FactoryException ex) {
                    throw ex;
                } catch (Exception ex) {
                    throw new FactoryException("Error creating workflow factory " + clazz, ex);
                }
            }

            initialized = true;
        } catch (FactoryException e) {
            throw e;
        } catch (Exception e) {
            throw new FactoryException("Error in workflow config", e);
        }
    }

    public boolean removeWorkflow(String workflow) throws FactoryException {
        return factory.removeWorkflow(workflow);
    }

    public boolean saveWorkflow(String name, WorkflowDescriptor descriptor, boolean replace) throws FactoryException {
        return factory.saveWorkflow(name, descriptor, replace);
    }

    /**
     * Load the default configuration from the current context classloader.
     * The search order is:
     * <li>Specified URL</li>
     * <li>osworkflow.xml</li>
     * <li>/osworkflow.xml</li>
     * <li>META-INF/osworkflow.xml</li>
     * <li>/META-INF/osworkflow.xml</li>
     */
    protected InputStream getInputStream(URL url) {
        InputStream is = null;

        if (url != null) {
            try {
                is = url.openStream();
            } catch (Exception ex) {
            }
        }

        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

        if (is == null) {
            try {
                is = classLoader.getResourceAsStream("osworkflow.xml");
            } catch (Exception e) {
            }
        }

        if (is == null) {
            try {
                is = classLoader.getResourceAsStream("/osworkflow.xml");
            } catch (Exception e) {
            }
        }

        if (is == null) {
            try {
                is = classLoader.getResourceAsStream("META-INF/osworkflow.xml");
            } catch (Exception e) {
            }
        }

        if (is == null) {
            try {
                is = classLoader.getResourceAsStream("/META-INF/osworkflow.xml");
            } catch (Exception e) {
            }
        }

        return is;
    }

    /**
     * Get the workflow factory for this configuration.
     * This method should never ever be called from client code!
     */
    WorkflowFactory getFactory() {
        return factory;
    }
}