AIR.Common.Configuration.AppSettings.java Source code

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Here is the source code for AIR.Common.Configuration.AppSettings.java

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/*******************************************************************************
 * Educational Online Test Delivery System 
 * Copyright (c) 2014 American Institutes for Research
 *   
 * Distributed under the AIR Open Source License, Version 1.0 
 * See accompanying file AIR-License-1_0.txt or at
 * http://www.smarterapp.org/documents/American_Institutes_for_Research_Open_Source_Software_License.pdf
 ******************************************************************************/
package AIR.Common.Configuration;

import org.apache.commons.lang.StringUtils;

import AIR.Common.Helpers.InvalidCastException;
import AIR.Common.Helpers._Ref;

// / <summary>
// / This class is used to get app settings out of web.config or a database.
// / </summary>
public class AppSettings {
    private static IAppSettingsHandler _handler;

    // / <summary>
    // / Set the handler used to lookup settings. In this handler you
    // / should figure out what the current client is and other context
    // / related issues.
    // / </summary>
    public static void setHandler(IAppSettingsHandler handler) {
        _handler = handler;
    }

    // / <summary>
    // / Lookup an app settings.
    // / </summary>
    // / <typeparam name="T">The data type of the setting. Right now there is only
    // string, bool and int.</typeparam>
    // / <param name="name">The name of the app setting key.</param>
    // / <param name="defaultValue">A default value in case the app setting is not
    // found.</param>
    // / <returns></returns>
    public static <T> AppSetting<T> get(String name, T defaultValue,
            AppSettingsHelperMethodWrapper<T> appSettingsHelper) {
        // first check web.config
        if (AppSettingsHelper.exists(name)) {
            T value = appSettingsHelper.getValue(name, defaultValue);
            return new AppSetting<T>(name, value);
        }
        // TODO Shiva. I need to revising the following if loop.
        // if a getter function was assigned then load from that
        if (_handler != null) {
            _Ref<T> value = new _Ref<T>(defaultValue);
            if (_handler.get(name, value)) {
                try {
                    return new AppSetting<T>(name, (T) (value.get()));
                } catch (Exception ice) {
                    throw new InvalidCastException(String.format("%1$s (%2$s)", ice.getMessage(), name), ice);
                }
            }
        }

        // return default
        return new AppSetting<T>(name, defaultValue);
    }

    public static AppSetting<Double> getDouble(String name) {
        return AppSettings.<Double>get(name, new Double(0), new AppSettingsHelperMethodWrapper<Double>() {
            @Override
            public Double getValue(String key, Double defaultValue) {
                return AppSettingsHelper.getDouble(key, defaultValue);
            }
        });
    }

    public static AppSetting<Integer> getInteger(String name) {
        return getInteger(name, 0);
    }

    public static AppSetting<Integer> getInteger(String name, final int defaultValue) {
        return AppSettings.<Integer>get(name, defaultValue, new AppSettingsHelperMethodWrapper<Integer>() {
            @Override
            public Integer getValue(String key, Integer defaultValue) {
                return AppSettingsHelper.getInt32(key, defaultValue);
            }
        });
    }

    public static AppSetting<Long> getLong(String name) {
        return AppSettings.<Long>get(name, new Long(0), new AppSettingsHelperMethodWrapper<Long>() {
            @Override
            public Long getValue(String key, Long defaultValue) {
                return AppSettingsHelper.getInt64(key, defaultValue);
            }
        });
    }

    public static AppSetting<Boolean> getBoolean(String name) {
        return AppSettings.<Boolean>get(name, false, new AppSettingsHelperMethodWrapper<Boolean>() {
            @Override
            public Boolean getValue(String key, Boolean defaultValue) {
                return AppSettingsHelper.getBoolean(key, defaultValue);
            }
        });
    }

    public static AppSetting<String> getString(String name) {
        return AppSettings.<String>get(name, null, new AppSettingsHelperMethodWrapper<String>() {
            @Override
            public String getValue(String key, String defaultValue) {
                return AppSettingsHelper.get(key, defaultValue);
            }
        });
    }

    public static Object parseString(String type, String value) {
        switch (type.toLowerCase()) {
        case "boolean":
            return new Boolean(value);
        case "integer":
            return new Integer(value);
        default:
            return value; // default also covers "string"
        }
    }

    /*
     * function to check if a AppSetting is empty or null. It not only checks the
     * AppSetting object but also check the internal value to be null.
     * 
     * TODO Sajib/Shiva : See if there is anyway to use TypeReference to change
     * the arguement list to AppSetting<T> instead.
     */
    public static boolean isNullOrEmptyString(AppSetting<String> setting) {
        if (setting == null)
            return true;

        return StringUtils.isEmpty(setting.getValue());
    }

    private interface AppSettingsHelperMethodWrapper<T> {
        T getValue(String key, T defaultValue);
    }

}