org.jgroups.conf.ConfiguratorFactory Maven / Gradle / Ivy

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package org.jgroups.conf;

import org.jgroups.Global;
import org.jgroups.util.Util;
import org.w3c.dom.Element;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Objects;

/**
 * The ConfigurationFactory is a factory that returns a protocol stack configurator.
 * The protocol stack configurator is an object that read a stack configuration and
 * parses it so that the ProtocolStack can create a stack.
 * 

 * Currently the factory returns one of the following objects:

 * 1. XmlConfigurator - parses XML files

 * 2. PlainConfigurator - uses the old style strings UDP:FRAG: etc etc

 *
 * @author Filip Hanik ([email protected])
 * @author Bela Ban
 */
public class ConfiguratorFactory {
    public static final String JAXP_MISSING_ERROR_MSG="the required XML parsing classes are not available; " +
      "make sure that JAXP compatible libraries are in the classpath.";


    protected ConfiguratorFactory() {
    }

    /**
     * Returns a protocol stack configurator based on the XML configuration provided by the specified File.
     * 
     * @param file a File with a JGroups XML configuration.
     * @return a {@code ProtocolStackConfigurator} containing the stack configuration.
     * @throws Exception if problems occur during the configuration of the protocol stack.
     */
    public static ProtocolStackConfigurator getStackConfigurator(File file) throws Exception {
        checkJAXPAvailability();
        InputStream input=getConfigStream(file);
        return XmlConfigurator.getInstance(input);
    }

    public static ProtocolStackConfigurator getStackConfigurator(InputStream input) throws Exception {
        return XmlConfigurator.getInstance(input);
    }


    /**
     * Returns a protocol stack configurator based on the provided properties string.
     * @param properties a string representing a system resource containing a JGroups XML configuration, a URL pointing
     *                   to a JGroups XML configuration or a string representing a file name that contains a JGroups
     *                   XML configuration.
     */
    public static ProtocolStackConfigurator getStackConfigurator(String properties) throws Exception {
        if(properties == null)
            properties=Global.DEFAULT_PROTOCOL_STACK;

        // Attempt to treat the properties string as a pointer to an XML configuration.
        XmlConfigurator configurator=getXmlConfigurator(Objects.requireNonNull(properties));

        if(configurator != null) // did the properties string point to a JGroups XML configuration ?
            return configurator;
        throw new IllegalStateException(String.format("configuration %s not found or invalid", properties));
    }



    public static InputStream getConfigStream(File file) throws Exception {
        return new FileInputStream(Objects.requireNonNull(file));
    }



    /**
     * Returns a JGroups XML configuration InputStream based on the provided properties string.
     *
     * @param properties a string representing a system resource containing a JGroups XML configuration, a string
     *                   representing a URL pointing to a JGroups ML configuration, or a string representing
     *                   a file name that contains a JGroups XML configuration.
     * @throws IOException  if the provided properties string appears to be a valid URL but is unreachable.
     */
    public static InputStream getConfigStream(String properties) throws IOException {
        InputStream configStream = null;

        // Check to see if the properties string is the name of a file.
        try {
            configStream=new FileInputStream(properties);
        }
        catch(FileNotFoundException fnfe) {
            // the properties string is likely not a file
        }

        // Check to see if the properties string is a URL.
        if(configStream == null) {
            try {
                configStream=new URL(properties).openStream();
            }
            catch (MalformedURLException mre) {
                // the properties string is not a URL
            }
        }

        // Check to see if the properties string is the name of a resource, e.g. udp.xml.
        if(configStream == null && properties.endsWith("xml"))
            configStream=Util.getResourceAsStream(properties, ConfiguratorFactory.class);
        return configStream;
    }


    public static InputStream getConfigStream(Object properties) throws IOException {
        InputStream input=null;

        // added by bela: for null String props we use the default properties
        if(properties == null)
            properties=Global.DEFAULT_PROTOCOL_STACK;

        if(properties instanceof URL) {
            try {
                input=((URL)properties).openStream();
            }
            catch(Throwable t) {
            }
        }

        // if it is a string, then it could be a plain string or a url
        if(input == null && properties instanceof String)
            input=getConfigStream((String)properties);

        // try a regular file
        if(input == null && properties instanceof File) {
            try {
                input=new FileInputStream((File)properties);
            }
            catch(Throwable t) {
            }
        }

        if(input != null)
            return input;

        if(properties instanceof Element) {
            return getConfigStream(properties);
        }

        return new ByteArrayInputStream(((String)properties).getBytes());
    }




    /**
     * Returns an XmlConfigurator based on the provided properties string (if possible).
     *
     * @param properties a string representing a system resource containing a JGroups XML configuration, a string
     *                   representing a URL pointing to a JGroups ML configuration, or a string representing a file
     *                   name that contains a JGroups XML configuration.
     * @return an XmlConfigurator instance based on the provided properties string; {@code null} if the provided
     *         properties string does not point to an XML configuration.
     * @throws IOException  if the provided properties string appears to be a valid URL but is unreachable, or if the
     *                      JGroups XML configuration pointed to by the URL can not be parsed.
     */
    static XmlConfigurator getXmlConfigurator(String properties) throws IOException {
        XmlConfigurator returnValue=null;
        InputStream configStream=getConfigStream(properties);
        if(configStream == null && properties.endsWith("xml"))
            throw new FileNotFoundException(String.format(Util.getMessage("FileNotFound"), properties));

        if (configStream != null) {
            checkJAXPAvailability();
            returnValue=XmlConfigurator.getInstance(configStream);
        }

        return returnValue;
    }



    /**
     * Checks the availability of the JAXP classes on the classpath.
     * @throws NoClassDefFoundError if the required JAXP classes are not availabile on the classpath.
     */
    static void checkJAXPAvailability() {
        try {
            XmlConfigurator.class.getName();
        }
        catch (NoClassDefFoundError error) {
            Error tmp=new NoClassDefFoundError(JAXP_MISSING_ERROR_MSG);
            tmp.initCause(error);
            throw tmp;
        }
    }

}