canonicalutilities.java

A Java web application, based on Struts and Hibernate, that serves as an online running log. Users m

/* @LICENSE_COPYRIGHT@ */
package net.sf.irunninglog.canonical;

import java.util.ArrayList;
import java.util.List;

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

import net.sf.irunninglog.util.ResourceManager;

/**
 * Utility class used to lookup values related to canonical objects' fields.
 * The type of values that can be retrieved include: field labels, max/min
 * lengths. max/min values, and valid values.  The methods included in this
 * class use the canonical ID and field name to lookup the desired values from
 * the application's property files.
 *
 * @author <a href="mailto:[e-mail]">Allan Lewis</a>
 * @version $Revision: 1.2 $ $Date: 2005/06/29 02:48:09 $
 * @since iRunningLog 1.0
 */
public final class CanonicalUtilities {

    /** <code>Log</code> instance for this class. */
    private static final Log LOG = LogFactory.getLog(CanonicalUtilities.class);

    /** Delimiter used in building lookup keys. */
    private static final String DELIMITER = ".";
    /** Suffix used to build keys for label lookups. */
    private static final String LABEL = "label";
    /** Suffix used to build keys for min length lookups. */
    private static final String MIN_LENGTH = "minLength";
    /** Suffix used to build keys for max length lookups. */
    private static final String MAX_LENGTH = "maxLength";
    /** Suffix used to build keys for min value lookups. */
    private static final String MIN_VALUE = "minValue";
    /** Suffix used to build keys for max value lookups. */
    private static final String MAX_VALUE = "maxValue";
    /** Suffix used to build keys for number of valid value lookups. */
    private static final String NUM_VALID_VALUES = "numValidValues";
    /** Suffix used to build keys for valid value lookups. */
    private static final String VALID_VALUE = "validValue";
    /** The <code>ResourceManager</code> used to look up values. */
    private static final ResourceManager MANAGER;

    static {
        MANAGER = ResourceManager.getInstance();
    }

    /** This is a utility class - does not expose a constructor. */
    private CanonicalUtilities() { }

    /**
     * Get the label value for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose label we want
     * @return The label value for the field
     */
    public static String getLabel(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, LABEL);
        String label = getString(key);
        if (LOG.isDebugEnabled()) {
            LOG.debug("getLabel: Label for canonicalId=" + canonicalId
                      + ", fieldName=" + fieldName + " is '" + label + "'");
        }
        return label;
    }

    /**
     * Get the minimum length value for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose minimum length we want
     * @return The minimum length value for the field
     */
    public static int getMinLength(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, MIN_LENGTH);
        int minLength = Integer.parseInt(getString(key));
        if (LOG.isDebugEnabled()) {
            LOG.debug("getMinLength: Min length for canonicalId=" + canonicalId
                      + ", fieldName=" + fieldName + " is '" + minLength + "'");
        }
        return minLength;
    }

    /**
     * Get the maximum length value for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose maximum length we want
     * @return The maximum length value for the field
     */
    public static int getMaxLength(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, MAX_LENGTH);
        int maxLength = Integer.parseInt(getString(key));
        if (LOG.isDebugEnabled()) {
            LOG.debug("getMaxLength: Max length for canonicalId=" + canonicalId
                      + ", fieldName=" + fieldName + " is '" + maxLength + "'");
        }
        return maxLength;
    }

    /**
     * Get the minimum value for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose minimum value we want
     * @return The minimum value for the field
     */
    public static double getMinValue(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, MIN_VALUE);
        double minValue = Double.parseDouble(getString(key));
        if (LOG.isDebugEnabled()) {
            LOG.debug("getMinValue: Min value for canonicalId=" + canonicalId
                      + ", fieldName=" + fieldName + " is '" + minValue + "'");
        }
        return minValue;
    }

    /**
     * Get the maximum value for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose maximum value we want
     * @return The maximum value for the field
     */
    public static double getMaxValue(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, MAX_VALUE);
        double maxValue = Double.parseDouble(getString(key));
        if (LOG.isDebugEnabled()) {
            LOG.debug("getMaxValue: Max value for canonicalId=" + canonicalId
                      + ", fieldName=" + fieldName + " is '" + maxValue + "'");
        }
        return maxValue;
    }

    /**
     * Get the list of valid (allowed) values for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field whose valid values we want
     * @return A list of the valid values for the field
     */
    public static List getValidValues(String canonicalId, String fieldName) {
        String key = getResourceKey(canonicalId, fieldName, NUM_VALID_VALUES);
        int numValidVals = Integer.parseInt(getString(key));
        if (LOG.isDebugEnabled()) {
            LOG.debug("getValidValues: Number of valid values for canonicalId="
                      + canonicalId + ", fieldName=" + fieldName + " is "
                      + numValidVals);
        }
        List validValues = new ArrayList();

        String value = null;
        for (int i = 0; i < numValidVals; i++) {
            key = getResourceKey(canonicalId, fieldName, VALID_VALUE + i);
            value = getString(key);
            validValues.add(value);
            if (LOG.isDebugEnabled()) {
                LOG.debug("getValidValues: valid value " + i + " for "
                          + "canonicalId=" + canonicalId + ", fieldName="
                          + fieldName + " is '" + value + "'");
            }
        }

        return validValues;
    }

    /**
     * Construct and return the key that will be used to lookup a property
     * for a canonical object's field.
     *
     * @param canonicalId The canonical ID of the object containing the field
     * @param fieldName The name of the field
     * @param type The type of field property to be looked up
     * @return A key that can be used to locate the desired value from the
     *         application's resource bundle(s)
     *
     */
    private static String getResourceKey(String canonicalId, String fieldName,
                                         String type) {
        return canonicalId + DELIMITER + fieldName + DELIMITER + type;
    }

    /**
     * Retrieve a value from the application's resource bundle(s). This
     * method can handle the actual work of using the
     * <code>ResourceManager</code> to get the desired value.
     *
     * @param key The key identifying the value to be retrieved
     * @return The value identified by the key
     * @see ResourceManager
     */
    private static String getString(String key) {
        return MANAGER.getString(key);
    }

}