edu.cornell.mannlib.vitro.webapp.config.ConfigurationProperties.java Source code

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Here is the source code for edu.cornell.mannlib.vitro.webapp.config.ConfigurationProperties.java

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/* $This file is distributed under the terms of the license in /doc/license.txt$ */

package edu.cornell.mannlib.vitro.webapp.config;

import java.util.Map;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Provides an mechanism for modules to read the configuration properties that
 * are attached to the servlet context.
 * 
 * The customary behavior is for ConfigurationPropertiesSetup to create a
 * ConfigurationPropertiesImpl, which will obtain the properties from the
 * build.properties file and the runtime.properties file.
 */
public abstract class ConfigurationProperties {
    private static final Log log = LogFactory.getLog(ConfigurationProperties.class);

    /** The bean is attached to the session by this name. */
    private static final String ATTRIBUTE_NAME = ConfigurationProperties.class.getName();

    /** If they ask for a bean before one has been set, they get this. */
    private static final ConfigurationProperties DUMMY_PROPERTIES = new DummyConfigurationProperties();

    // ----------------------------------------------------------------------
    // static methods
    // ----------------------------------------------------------------------

    public static ConfigurationProperties getBean(ServletRequest request) {
        if (request == null) {
            throw new NullPointerException("request may not be null.");
        }
        if (!(request instanceof HttpServletRequest)) {
            throw new IllegalArgumentException("request must be an HttpServletRequest");
        }
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        return getBean(httpRequest.getSession());
    }

    public static ConfigurationProperties getBean(HttpSession session) {
        if (session == null) {
            throw new NullPointerException("session may not be null.");
        }
        return getBean(session.getServletContext());
    }

    public static ConfigurationProperties getBean(HttpServlet servlet) {
        if (servlet == null) {
            throw new NullPointerException("servlet may not be null.");
        }
        return getBean(servlet.getServletContext());
    }

    public static ConfigurationProperties getBean(ServletContextEvent sce) {
        if (sce == null) {
            throw new NullPointerException("sce may not be null.");
        }
        return getBean(sce.getServletContext());
    }

    public static ConfigurationProperties getBean(ServletConfig servletConfig) {
        if (servletConfig == null) {
            throw new NullPointerException("servletConfig may not be null.");
        }
        return getBean(servletConfig.getServletContext());
    }

    public static ConfigurationProperties getBean(ServletContext context) {
        if (context == null) {
            throw new NullPointerException("context may not be null.");
        }

        Object o = context.getAttribute(ATTRIBUTE_NAME);
        if (o == null) {
            log.error("ConfigurationProperties bean has not been set.");
            return DUMMY_PROPERTIES;
        } else if (!(o instanceof ConfigurationProperties)) {
            log.error("Error: ConfigurationProperties was set to an " + "invalid object: " + o);
            return DUMMY_PROPERTIES;
        }

        return (ConfigurationProperties) o;
    }

    /**
     * Protected access, so the Stub class can call it for unit tests.
     * Otherwise, this should only be called by ConfigurationPropertiesSetup.
     */
    protected static void setBean(ServletContext context, ConfigurationProperties bean) {
        if (context == null) {
            throw new NullPointerException("context may not be null.");
        }
        if (bean == null) {
            throw new NullPointerException("bean may not be null.");
        }
        context.setAttribute(ATTRIBUTE_NAME, bean);
        log.info(bean);
    }

    /** Package access, so unit tests can call it. */
    static void removeBean(ServletContext context) {
        if (context == null) {
            throw new NullPointerException("context may not be null.");
        }
        context.removeAttribute(ATTRIBUTE_NAME);
    }

    // ----------------------------------------------------------------------
    // The interface
    // ----------------------------------------------------------------------

    /**
     * Get the value of the property, or <code>null</code> if the property has
     * not been assigned a value.
     */
    public abstract String getProperty(String key);

    /**
     * Get the value of the property, or use the default value if the property
     * has not been assigned a value.
     */
    public abstract String getProperty(String key, String defaultValue);

    /**
     * Get a copy of the map of the configuration properties and their settings.
     * Because this is a copy, it cannot be used to modify the settings.
     */
    public abstract Map<String, String> getPropertyMap();

}