appdata.java

一个数据访问层Torque3.1的生成器的源代码

package org.apache.torque.engine.database.model;

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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
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 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import org.apache.commons.lang.StringUtils;

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

import org.apache.torque.engine.EngineException;
import org.apache.torque.engine.database.transform.DTDResolver;

import org.xml.sax.Attributes;

/**
 * A class for holding application data structures.
 *
 * @author <a href="mailto:[e-mail]>Leon Messerschmidt</a>
 * @author <a href="mailto:[e-mail]>John McNally</a>
 * @author <a href="mailto:[e-mail]>Daniel Rall</a>
 * @version $Id: AppData.java,v 1.4 2003/07/25 16:40:30 henning Exp $
 */
public class AppData
{
    /** Logging class from commons.logging */
    private static Log log = LogFactory.getLog(AppData.class);

    /**
     * The list of databases for this application.
     */
    private List dbList = new ArrayList(5);

    /**
     * The table of idiosyncrasies for various database types.
     */
    private Map idiosyncrasyTable = new HashMap(8);

    /**
     * The type for our databases.
     */
    private String databaseType;

    /**
     * The base of the path to the properties file, including trailing slash.
     */
    private String basePropsFilePath;

    /**
     * Name of the database. Only one database definition
     * is allowed in one XML descriptor.
     */
    private String name;

    // flag to complete initialization only once.
    boolean isInitialized;

    /**
     * Creates a new instance for the specified database type.
     *
     * @param databaseType The default type for any databases added to
     * this application model.
     * @param basePropsFilePath The base of the path to the properties
     * file, including trailing slash.
     */
    public AppData(String databaseType, String basePropsFilePath)
    {
        this.basePropsFilePath = basePropsFilePath;
        this.databaseType = databaseType;
    }

    /**
     * Each database has its own list of idiosyncrasies which can be
     * configured by editting its <code>db.props</code> file.
     *
     * @param databaseType The type of database to retrieve the
     * properties of.
     * @return The idiosyncrasies of <code>databaseType</code>.
     * @exception EngineException Couldn't locate properties file.
     */
    protected Properties getIdiosyncrasies(String databaseType)
        throws EngineException
    {
        Properties idiosyncrasies
                = (Properties) idiosyncrasyTable.get(databaseType);

        // If we haven't yet loaded the properties and we have the
        // information to do so, proceed with loading.
        if (idiosyncrasies == null && basePropsFilePath != null
                && databaseType != null)
        {
            idiosyncrasies = new Properties();
            File propsFile = new File(basePropsFilePath + databaseType,
                                      "db.props");
            if (propsFile.exists())
            {
                try
                {
                    idiosyncrasies.load(new FileInputStream(propsFile));
                }
                catch (Exception e)
                {
                    log.error(e, e);
                }
                idiosyncrasyTable.put(databaseType, idiosyncrasies);
            }
            else
            {
                try
                {
                    String path = '/' + basePropsFilePath + databaseType
                            + "/db.props";
                    idiosyncrasies.load(getClass().getResourceAsStream(path));
                }
                catch (Exception e)
                {
                    log.error(e, e);
                }
            }

            if (idiosyncrasies.isEmpty())
            {
                throw new EngineException("Database-specific properties "
                        + "file does not exist: "
                        + propsFile.getAbsolutePath());
            }
        }
        return idiosyncrasies;
    }

    /**
     * Set the name of the database.
     *
     * @param name of the database.
     */
    public void setName(String name)
    {
        this.name = name;
    }

    /**
     * Get the name of the database.
     *
     * @return String name
     */
    public String getName()
    {
        return name;
    }

    /**
     * Get the short name of the database (without the '-schema' postfix).
     *
     * @return String name
     */
    public String getShortName()
    {
        return StringUtils.replace(name, "-schema", "");
    }

    /**
     * Get database object.
     *
     * @return Database database
     */
    public Database getDatabase()
            throws EngineException
    {
        doFinalInitialization();
        return (Database) dbList.get(0);
    }

    /**
     * Return an array of all databases
     *
     * @return Array of Database objects
     */
    public Database[] getDatabases()
            throws EngineException
    {
        doFinalInitialization();
        int size = dbList.size();
        Database[] dbs = new Database[size];
        for (int i = 0; i < size; i++)
        {
            dbs[i] = (Database) dbList.get(i);
        }
        return dbs;
    }

    /**
     * Returns whether this application has multiple databases.
     *
     * @return true if the application has multiple databases
     */
    public boolean hasMultipleDatabases()
    {
        return (dbList.size() > 1);
    }

    /**
     * Return the database with the specified name.
     *
     * @param name database name
     * @return A Database object.  If it does not exist it returns null
     */
    public Database getDatabase (String name)
            throws EngineException
    {
        doFinalInitialization();
        for (Iterator i = dbList.iterator(); i.hasNext();)
        {
            Database db = (Database) i.next();
            if (db.getName().equals(name))
            {
                return db;
            }
        }
        return null;
    }

    /**
     * An utility method to add a new database from an xml attribute.
     *
     * @param attrib the xml attributes
     * @return the database
     */
    public Database addDatabase(Attributes attrib)
    {
        Database db = new Database();
        db.loadFromXML (attrib);
        addDatabase (db);
        return db;
    }

    /**
     * Add a database to the list and sets the AppData property to this
     * AppData
     *
     * @param db the database to add
     */
    public void addDatabase(Database db)
    {
        db.setAppData (this);
        if (db.getName() == null)
        {
            /** @task check this */
            db.setName("default"); // Torque.getDefaultDB());
        }
        if (db.getDatabaseType() == null)
        {
            db.setDatabaseType(databaseType);
        }
        dbList.add(db);
    }

    private void doFinalInitialization()
            throws EngineException
    {
        if (!isInitialized)
        {
            Iterator dbs = dbList.iterator();
            while (dbs.hasNext())
            {
                ((Database) dbs.next()).doFinalInitialization();
            }
            isInitialized = true;
        }
    }

    /**
     * Creats a string representation of this AppData.
     * The representation is given in xml format.
     *
     * @return representation in xml format
     */
    public String toString()
    {
        StringBuffer result = new StringBuffer();

        result.append ("<?xml version=\"1.0\"?>\n");
        result.append ("<!DOCTYPE database SYSTEM \""
                + DTDResolver.WEB_SITE_DTD + "\">\n");
        result.append("<!-- Autogenerated by SQLToXMLSchema! -->\n");
        for (Iterator i = dbList.iterator(); i.hasNext();)
        {
            result.append (i.next());
        }
        return result.toString();
    }
}