com.glaf.core.provider.ServiceProviderConfigReader.java Source code

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Here is the source code for com.glaf.core.provider.ServiceProviderConfigReader.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * 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
 * 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 com.glaf.core.provider;

import java.io.FileInputStream;
import java.io.InputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import com.glaf.core.util.Check;
import com.glaf.core.util.BaseClassLoader;

/**
 * Reads the provider config file and processes it. The provider config file can
 * be used to configure the ServiceProvider. See the provider config xml file(s)
 * in the WEB-INF directory for examples.
 * 
 */
class ServiceProviderConfigReader {
    protected static final Log log = LogFactory.getLog(ServiceProviderConfigReader.class);

    void read(String prefix, InputStream is) {
        try {
            final SAXReader reader = new SAXReader();
            final Document doc = reader.read(is);
            process(prefix, doc);
        } catch (final Exception e) {
            throw new ServiceProviderException(e);
        }
    }

    void read(String prefix, String fileLocation) {
        try {
            final SAXReader reader = new SAXReader();
            final Document doc = reader.read(new FileInputStream(fileLocation));
            process(prefix, doc);
        } catch (final Exception ex) {
            ex.printStackTrace();
            throw new ServiceProviderException(ex);
        }
    }

    void process(String prefix, Document doc) {
        checkName(doc.getRootElement(), "provider");
        for (final Object o : doc.getRootElement().elements()) {
            final Element elem = (Element) o;
            checkName(elem, "bean");
            // now check for three children:
            final String name = getValue(elem, "name", true);
            final String clzName = getValue(elem, "class", true);
            Class<?> clz = null;
            try {
                clz = BaseClassLoader.getInstance().loadClass(clzName);
            } catch (final ClassNotFoundException e) {
                // catch ClassNotFoundException
                log.warn("Class " + clzName + " can not be loaded. This can happen "
                        + "when rebuilding after installing new modules. "
                        + "The system needs to be restarted to find " + "new services");
                continue;
            }
            if (ServiceModulePrefixRequired.class.isAssignableFrom(clz) && prefix != null
                    && prefix.trim().length() > 0) {
                ServiceProvider.getInstance().register(prefix + "." + name, clz, true);
            } else {

                ServiceProvider.getInstance().register(name, clz, true);
            }
        }
    }

    private String getValue(Element parentElem, String name, boolean mandatory) {
        final Element valueElement = parentElem.element(name);
        if (mandatory) {
            Check.isNotNull(valueElement, "Element with name " + name + " not found");
        } else if (valueElement == null) {
            return null;
        }
        return valueElement.getText();
    }

    private void checkName(Element elem, String expectedName) {
        Check.isTrue(elem.getName().equals(expectedName),
                "The element should have the name: " + expectedName + " but is has name " + elem.getName());
    }
}