Java tutorial
/* * $Header: /cvsroot/valuelist/valuelist/src/java/net/mlw/vlh/adapter/jdbc/dynabean/fix/JDBCDynaClass.java,v 1.2 2005/08/19 16:06:29 smarek Exp $ * $Revision: 1.2 $ * $Date: 2005/08/19 16:06:29 $ * * ==================================================================== * * The Apache Software License, Version 1.1 * * Copyright (c) 2001-2003 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. 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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package net.mlw.vlh.adapter.jdbc.dynabean.fix; import java.io.Serializable; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.beanutils.DynaBean; import org.apache.commons.beanutils.DynaClass; import org.apache.commons.beanutils.DynaProperty; /** * <p>Provides common logic for JDBC implementations of {@link DynaClass}.</p> * * @author Craig R. McClanahan * @author George Franciscus * @version $Revision: 1.2 $ $Date: 2005/08/19 16:06:29 $ */ abstract class JDBCDynaClass implements DynaClass, Serializable { // ----------------------------------------------------- Instance Variables /** * <p>Flag defining whether column names should be lower cased when * converted to property names.</p> */ protected boolean lowerCase = true; /** * <p>Flag defining whether column names should be the column name * or the column label.</p> */ protected boolean useName = true; /** * <p>The set of dynamic properties that are part of this * {@link DynaClass}.</p> */ protected DynaProperty properties[] = null; /** * <p>The set of dynamic properties that are part of this * {@link DynaClass}, keyed by the property name. Individual descriptor * instances will be the same instances as those in the * <code>properties</code> list.</p> */ protected Map propertiesMap = new HashMap(); // ------------------------------------------------------ DynaClass Methods /** * <p>Return the name of this DynaClass (analogous to the * <code>getName()</code> method of <code>java.lang.Class</code), which * allows the same <code>DynaClass</code> implementation class to support * different dynamic classes, with different sets of properties.</p> */ public String getName() { return (this.getClass().getName()); } /** * <p>Return a property descriptor for the specified property, if it * exists; otherwise, return <code>null</code>.</p> * * @param name Name of the dynamic property for which a descriptor * is requested * * @exception IllegalArgumentException if no property name is specified */ public DynaProperty getDynaProperty(String name) { if (name == null) { throw new IllegalArgumentException("No property name specified"); } return ((DynaProperty) propertiesMap.get(name)); } /** * <p>Return an array of <code>ProperyDescriptors</code> for the properties * currently defined in this DynaClass. If no properties are defined, a * zero-length array will be returned.</p> */ public DynaProperty[] getDynaProperties() { return (properties); } /** * <p>Instantiate and return a new DynaBean instance, associated * with this DynaClass. <strong>NOTE</strong> - This operation is not * supported, and throws an exception.</p> * * @exception IllegalAccessException if the Class or the appropriate * constructor is not accessible * @exception InstantiationException if this Class represents an abstract * class, an array class, a primitive type, or void; or if instantiation * fails for some other reason */ public DynaBean newInstance() throws IllegalAccessException, InstantiationException { throw new UnsupportedOperationException("newInstance() not supported"); } /** * <p>Loads and returns the <code>Class</code> of the given name. * By default, a load from the thread context class loader is attempted. * If there is no such class loader, the class loader used to load this * class will be utilized.</p> * * @exception SQLException if an exception was thrown trying to load * the specified class */ protected Class loadClass(String className) throws SQLException { try { ClassLoader cl = Thread.currentThread().getContextClassLoader(); if (cl == null) { cl = this.getClass().getClassLoader(); } return (cl.loadClass(className)); } catch (Exception e) { throw new SQLException("Cannot load column class '" + className + "': " + e); } } /** * <p>Factory method to create a new DynaProperty for the given index * into the result set metadata.</p> * * @param metadata is the result set metadata * @param i is the column index in the metadata * @return the newly created DynaProperty instance */ protected DynaProperty createDynaProperty(ResultSetMetaData metadata, int i) throws SQLException { String name = (useName) ? metadata.getColumnName(i) : metadata.getColumnLabel(i); if (lowerCase) { name = name.toLowerCase(); } String className = null; try { className = metadata.getColumnClassName(i); } catch (SQLException e) { // this is a patch for HsqlDb to ignore exceptions // thrown by its metadata implementation } // Default to Object type if no class name could be retrieved // from the metadata Class clazz = Object.class; if (className != null) { clazz = loadClass(className); } return new DynaProperty(name, clazz); } /** * <p>Introspect the metadata associated with our result set, and populate * the <code>properties</code> and <code>propertiesMap</code> instance * variables.</p> * * @param resultSet The <code>resultSet</code> whose metadata is to * be introspected * * @exception SQLException if an error is encountered processing the * result set metadata */ protected void introspect(ResultSet resultSet) throws SQLException { // Accumulate an ordered list of DynaProperties List list = new ArrayList(); ResultSetMetaData metadata = resultSet.getMetaData(); int n = metadata.getColumnCount(); for (int i = 1; i <= n; i++) { // JDBC is one-relative! DynaProperty dynaProperty = createDynaProperty(metadata, i); if (dynaProperty != null) { list.add(dynaProperty); } } // Convert this list into the internal data structures we need properties = (DynaProperty[]) list.toArray(new DynaProperty[list.size()]); for (int i = 0; i < properties.length; i++) { propertiesMap.put(properties[i].getName(), properties[i]); } } }