众里寻他千百度 暮然回首 那人却在灯火阑珊处……

　　关于 c3p0 各个属性的解释，我想这个是最全的，不用 Google 上苦苦寻觅了，

　　众里寻他千百度 暮然回首 c3p0却在灯火阑珊处……

 

　　hibernate-3.2.zip 中有源码并注释……，先附全文如下：

 

//$Id: Environment.java 10580 2006-10-16 02:48:43Z [email protected] $
package org.hibernate.cfg;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.Timestamp;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;

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

import org.hibernate.HibernateException;
import org.hibernate.bytecode.BytecodeProvider;
import org.hibernate.util.ConfigHelper;
import org.hibernate.util.PropertiesHelper;

/**
 * Provides access to configuration info passed in <tt>Properties</tt> objects.
 * <br><br>
 * Hibernate has two property scopes:
 * <ul>
 * <li><b>Factory-level</b> properties may be passed to the <tt>SessionFactory</tt> when it
 * instantiated. Each instance might have different property values. If no
 * properties are specified, the factory calls <tt>Environment.getProperties()</tt>.
 * <li><b>System-level</b> properties are shared by all factory instances and are always
 * determined by the <tt>Environment</tt> properties.
 * </ul>
 * The only system-level properties are
 * <ul>
 * <li><tt>hibernate.jdbc.use_streams_for_binary</tt>
 * <li><tt>hibernate.cglib.use_reflection_optimizer</tt>
 * </ul>
 * <tt>Environment</tt> properties are populated by calling <tt>System.getProperties()</tt>
 * and then from a resource named <tt>/hibernate.properties</tt> if it exists. System
 * properties override properties specified in <tt>hibernate.properties</tt>.<br>
 * <br>
 * The <tt>SessionFactory</tt> is controlled by the following properties.
 * Properties may be either be <tt>System</tt> properties, properties
 * defined in a resource named <tt>/hibernate.properties</tt> or an instance of
 * <tt>java.util.Properties</tt> passed to
 * <tt>Configuration.buildSessionFactory()</tt><br>
 * <br>
 * <table>
 * <tr><td><b>property</b></td><td><b>meaning</b></td></tr>
 * <tr>
 *   <td><tt>hibernate.dialect</tt></td>
 *   <td>classname of <tt>org.hibernate.dialect.Dialect</tt> subclass</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.cache.provider_class</tt></td>
 *   <td>classname of <tt>org.hibernate.cache.CacheProvider</tt>
 *   subclass (if not specified EHCache is used)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.connection.provider_class</tt></td>
 *   <td>classname of <tt>org.hibernate.connection.ConnectionProvider</tt>
 *   subclass (if not specified hueristics are used)</td>
 * </tr>
 * <tr><td><tt>hibernate.connection.username</tt></td><td>database username</td></tr>
 * <tr><td><tt>hibernate.connection.password</tt></td><td>database password</td></tr>
 * <tr>
 *   <td><tt>hibernate.connection.url</tt></td>
 *   <td>JDBC URL (when using <tt>java.sql.DriverManager</tt>)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.connection.driver_class</tt></td>
 *   <td>classname of JDBC driver</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.connection.isolation</tt></td>
 *   <td>JDBC transaction isolation level (only when using
 *     <tt>java.sql.DriverManager</tt>)
 *   </td>
 * </tr>
 *   <td><tt>hibernate.connection.pool_size</tt></td>
 *   <td>the maximum size of the connection pool (only when using
 *     <tt>java.sql.DriverManager</tt>)
 *   </td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.connection.datasource</tt></td>
 *   <td>databasource JNDI name (when using <tt>javax.sql.Datasource</tt>)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jndi.url</tt></td><td>JNDI <tt>InitialContext</tt> URL</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jndi.class</tt></td><td>JNDI <tt>InitialContext</tt> classname</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.max_fetch_depth</tt></td>
 *   <td>maximum depth of outer join fetching</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jdbc.batch_size</tt></td>
 *   <td>enable use of JDBC2 batch API for drivers which support it</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jdbc.fetch_size</tt></td>
 *   <td>set the JDBC fetch size</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jdbc.use_scrollable_resultset</tt></td>
 *   <td>enable use of JDBC2 scrollable resultsets (you only need this specify
 *   this property when using user supplied connections)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.jdbc.use_getGeneratedKeys</tt></td>
 *   <td>enable use of JDBC3 PreparedStatement.getGeneratedKeys() to retrieve
 *   natively generated keys after insert. Requires JDBC3+ driver and JRE1.4+</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.hbm2ddl.auto</tt></td>
 *   <td>enable auto DDL export</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.default_schema</tt></td>
 *   <td>use given schema name for unqualified tables (always optional)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.default_catalog</tt></td>
 *   <td>use given catalog name for unqualified tables (always optional)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.session_factory_name</tt></td>
 *   <td>If set, the factory attempts to bind this name to itself in the
 *   JNDI context. This name is also used to support cross JVM <tt>
 *   Session</tt> (de)serialization.</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.transaction.manager_lookup_class</tt></td>
 *   <td>classname of <tt>org.hibernate.transaction.TransactionManagerLookup</tt>
 *   implementor</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.transaction.factory_class</tt></td>
 *   <td>the factory to use for instantiating <tt>Transaction</tt>s.
 *   (Defaults to <tt>JDBCTransactionFactory</tt>.)</td>
 * </tr>
 * <tr>
 *   <td><tt>hibernate.query.substitutions</tt></td><td>query language token substitutions</td>
 * </tr>
 * </table>
 *
 * @see org.hibernate.SessionFactory
 * @author Gavin King
 */
public final class Environment {

 public static final String VERSION = "3.2.0";

 /**
  * <tt>ConnectionProvider</tt> implementor to use when obtaining connections
  */
 public static final String CONNECTION_PROVIDER ="hibernate.connection.provider_class";
 /**
  * JDBC driver class
  */
 public static final String DRIVER ="hibernate.connection.driver_class";
 /**
  * JDBC transaction isolation level
  */
 public static final String ISOLATION ="hibernate.connection.isolation";
 /**
  * JDBC URL
  */
 public static final String URL ="hibernate.connection.url";
 /**
  * JDBC user
  */
 public static final String USER ="hibernate.connection.username";
 /**
  * JDBC password
  */
 public static final String PASS ="hibernate.connection.password";
 /**
  * JDBC autocommit mode
  */
 public static final String AUTOCOMMIT ="hibernate.connection.autocommit";
 /**
  * Maximum number of inactive connections for Hibernate's connection pool
  */
 public static final String POOL_SIZE ="hibernate.connection.pool_size";
 /**
  * <tt>java.sql.Datasource</tt> JNDI name
  */
 public static final String DATASOURCE ="hibernate.connection.datasource";
 /**
  * prefix for arbitrary JDBC connection properties
  */
 public static final String CONNECTION_PREFIX = "hibernate.connection";

 /**
  * JNDI initial context class, <tt>Context.INITIAL_CONTEXT_FACTORY</tt>
  */
 public static final String JNDI_CLASS ="hibernate.jndi.class";
 /**
  * JNDI provider URL, <tt>Context.PROVIDER_URL</tt>
  */
 public static final String JNDI_URL ="hibernate.jndi.url";
 /**
  * prefix for arbitrary JNDI <tt>InitialContext</tt> properties
  */
 public static final String JNDI_PREFIX = "hibernate.jndi";
 /**
  * JNDI name to bind to <tt>SessionFactory</tt>
  */
 public static final String SESSION_FACTORY_NAME = "hibernate.session_factory_name";

 /**
  * Hibernate SQL <tt>Dialect</tt> class
  */
 public static final String DIALECT ="hibernate.dialect";
 /**
  * A default database schema (owner) name to use for unqualified tablenames
  */
 public static final String DEFAULT_SCHEMA = "hibernate.default_schema";
 /**
  * A default database catalog name to use for unqualified tablenames
  */
 public static final String DEFAULT_CATALOG = "hibernate.default_catalog";

 /**
  * Enable logging of generated SQL to the console
  */
 public static final String SHOW_SQL ="hibernate.show_sql";
 /**
  * Enable formatting of SQL logged to the console
  */
 public static final String FORMAT_SQL ="hibernate.format_sql";
 /**
  * Add comments to the generated SQL
  */
 public static final String USE_SQL_COMMENTS ="hibernate.use_sql_comments";
 /**
  * Maximum depth of outer join fetching
  */
 public static final String MAX_FETCH_DEPTH = "hibernate.max_fetch_depth";
 /**
  * The default batch size for batch fetching
  */
 public static final String DEFAULT_BATCH_FETCH_SIZE = "hibernate.default_batch_fetch_size";
 /**
  * Use <tt>java.io</tt> streams to read / write binary data from / to JDBC
  */
 public static final String USE_STREAMS_FOR_BINARY = "hibernate.jdbc.use_streams_for_binary";
 /**
  * Use JDBC scrollable <tt>ResultSet</tt>s. This property is only necessary when there is
  * no <tt>ConnectionProvider</tt>, ie. the user is supplying JDBC connections.
  */
 public static final String USE_SCROLLABLE_RESULTSET = "hibernate.jdbc.use_scrollable_resultset";
 /**
  * Tells the JDBC driver to attempt to retrieve row Id with the JDBC 3.0 PreparedStatement.getGeneratedKeys()
  * method. In general, performance will be better if this property is set to true and the underlying
  * JDBC driver supports getGeneratedKeys().
  */
 public static final String USE_GET_GENERATED_KEYS = "hibernate.jdbc.use_get_generated_keys";
 /**
  * Gives the JDBC driver a hint as to the number of rows that should be fetched from the database
  * when more rows are needed. If <tt>0</tt>, JDBC driver default settings will be used.
  */
 public static final String STATEMENT_FETCH_SIZE = "hibernate.jdbc.fetch_size";
 /**
  * Maximum JDBC batch size. A nonzero value enables batch updates.
  */
 public static final String STATEMENT_BATCH_SIZE = "hibernate.jdbc.batch_size";
 /**
  * Select a custom batcher.
  */
 public static final String BATCH_STRATEGY = "hibernate.jdbc.factory_class";
 /**
  * Should versioned data be included in batching?
  */
 public static final String BATCH_VERSIONED_DATA = "hibernate.jdbc.batch_versioned_data";
 /**
  * An XSLT resource used to generate "custom" XML
  */
 public static final String OUTPUT_STYLESHEET ="hibernate.xml.output_stylesheet";

 /**
  * Maximum size of C3P0 connection pool
  */
 public static final String C3P0_MAX_SIZE = "hibernate.c3p0.max_size";
 /**
  * Minimum size of C3P0 connection pool
  */
 public static final String C3P0_MIN_SIZE = "hibernate.c3p0.min_size";

 /**
  * Maximum idle time for C3P0 connection pool
  */
 public static final String C3P0_TIMEOUT = "hibernate.c3p0.timeout";
 /**
  * Maximum size of C3P0 statement cache
  */
 public static final String C3P0_MAX_STATEMENTS = "hibernate.c3p0.max_statements";
 /**
  * Number of connections acquired when pool is exhausted
  */
 public static final String C3P0_ACQUIRE_INCREMENT = "hibernate.c3p0.acquire_increment";
 /**
  * Idle time before a C3P0 pooled connection is validated
  */
 public static final String C3P0_IDLE_TEST_PERIOD = "hibernate.c3p0.idle_test_period";

 /**
  * Proxool/Hibernate property prefix
  */
 public static final String PROXOOL_PREFIX = "hibernate.proxool";
 /**
  * Proxool property to configure the Proxool Provider using an XML (<tt>/path/to/file.xml</tt>)
  */
 public static final String PROXOOL_XML = "hibernate.proxool.xml";
 /**
  * Proxool property to configure the Proxool Provider  using a properties file (<tt>/path/to/proxool.properties</tt>)
  */
 public static final String PROXOOL_PROPERTIES = "hibernate.proxool.properties";
 /**
  * Proxool property to configure the Proxool Provider from an already existing pool (<tt>true</tt> / <tt>false</tt>)
  */
 public static final String PROXOOL_EXISTING_POOL = "hibernate.proxool.existing_pool";
 /**
  * Proxool property with the Proxool pool alias to use
  * (Required for <tt>PROXOOL_EXISTING_POOL</tt>, <tt>PROXOOL_PROPERTIES</tt>, or
  * <tt>PROXOOL_XML</tt>)
  */
 public static final String PROXOOL_POOL_ALIAS = "hibernate.proxool.pool_alias";

 /**
  * Enable automatic session close at end of transaction
  */
 public static final String AUTO_CLOSE_SESSION = "hibernate.transaction.auto_close_session";
 /**
  * Enable automatic flush during the JTA <tt>beforeCompletion()</tt> callback
  */
 public static final String FLUSH_BEFORE_COMPLETION = "hibernate.transaction.flush_before_completion";
 /**
  * Specifies how Hibernate should release JDBC connections.
  */
 public static final String RELEASE_CONNECTIONS = "hibernate.connection.release_mode";
 /**
  * Context scoping impl for {@link org.hibernate.SessionFactory#getCurrentSession()} processing.
  */
 public static final String CURRENT_SESSION_CONTEXT_CLASS = "hibernate.current_session_context_class";
 /**
  * <tt>TransactionFactory</tt> implementor to use for creating <tt>Transaction</tt>s
  */
 public static final String TRANSACTION_STRATEGY = "hibernate.transaction.factory_class";
 /**
  * <tt>TransactionManagerLookup</tt> implementor to use for obtaining the <tt>TransactionManager</tt>
  */
 public static final String TRANSACTION_MANAGER_STRATEGY = "hibernate.transaction.manager_lookup_class";
 /**
  * JNDI name of JTA <tt>UserTransaction</tt> object
  */
 public static final String USER_TRANSACTION = "jta.UserTransaction";

 /**
  * The <tt>CacheProvider</tt> implementation class
  */
 public static final String CACHE_PROVIDER = "hibernate.cache.provider_class";
 /**
  * The <tt>CacheProvider</tt> implementation class
  */
 public static final String CACHE_PROVIDER_CONFIG = "hibernate.cache.provider_configuration_file_resource_path";
 /**
  * The <tt>CacheProvider</tt> JNDI namespace, if pre-bound to JNDI.
  */
 public static final String CACHE_NAMESPACE = "hibernate.cache.jndi";
 /**
  * Enable the query cache (disabled by default)
  */
 public static final String USE_QUERY_CACHE = "hibernate.cache.use_query_cache";
 /**
  * The <tt>QueryCacheFactory</tt> implementation class.
  */
 public static final String QUERY_CACHE_FACTORY = "hibernate.cache.query_cache_factory";
 /**
  * Enable the second-level cache (enabled by default)
  */
 public static final String USE_SECOND_LEVEL_CACHE = "hibernate.cache.use_second_level_cache";
 /**
  * Optimize the cache for mimimal puts instead of minimal gets
  */
 public static final String USE_MINIMAL_PUTS = "hibernate.cache.use_minimal_puts";
 /**
  * The <tt>CacheProvider</tt> region name prefix
  */
 public static final String CACHE_REGION_PREFIX = "hibernate.cache.region_prefix";
 /**
  * Enable use of structured second-level cache entries
  */
 public static final String USE_STRUCTURED_CACHE = "hibernate.cache.use_structured_entries";

 /**
  * Enable statistics collection
  */
 public static final String GENERATE_STATISTICS = "hibernate.generate_statistics";

 public static final String USE_IDENTIFIER_ROLLBACK = "hibernate.use_identifier_rollback";

 /**
  * Use bytecode libraries optimized property access
  */
 public static final String USE_REFLECTION_OPTIMIZER = "hibernate.bytecode.use_reflection_optimizer";

 /**
  * The classname of the HQL query parser factory
  */
 public static final String QUERY_TRANSLATOR = "hibernate.query.factory_class";
 /**
  * A comma-seperated list of token substitutions to use when translating a Hibernate
  * query to SQL
  */
 public static final String QUERY_SUBSTITUTIONS = "hibernate.query.substitutions";
 /**
  * Auto export/update schema using hbm2ddl tool. Valid values are <tt>update</tt>,
  * <tt>create</tt>, <tt>create-drop</tt> and <tt>validate</tt>.
  */
 public static final String HBM2DDL_AUTO = "hibernate.hbm2ddl.auto";

 /**
  * The {@link org.hibernate.exception.SQLExceptionConverter} to use for converting SQLExceptions
  * to Hibernate's JDBCException hierarchy.  The default is to use the configured
  * {@link org.hibernate.dialect.Dialect}'s preferred SQLExceptionConverter.
  */
 public static final String SQL_EXCEPTION_CONVERTER = "hibernate.jdbc.sql_exception_converter";

 /**
  * Enable wrapping of JDBC result sets in order to speed up column name lookups for
  * broken JDBC drivers
  */
 public static final String WRAP_RESULT_SETS = "hibernate.jdbc.wrap_result_sets";

 /**
  * Enable ordering of update statements by primary key value
  */
 public static final String ORDER_UPDATES = "hibernate.order_updates";

 /**
  * The EntityMode in which set the Session opened from the SessionFactory.
  */
    public static final String DEFAULT_ENTITY_MODE = "hibernate.default_entity_mode";

    /**
     * The jacc context id of the deployment
     */
 public static final String JACC_CONTEXTID = "hibernate.jacc_context_id";

 public static final String BYTECODE_PROVIDER = "hibernate.bytecode.provider";

 public static final String JPAQL_STRICT_COMPLIANCE= "hibernate.query.jpaql_strict_compliance";

 private static final BytecodeProvider BYTECODE_PROVIDER_INSTANCE;
 private static final boolean ENABLE_BINARY_STREAMS;
 private static final boolean ENABLE_REFLECTION_OPTIMIZER;
 private static final boolean JVM_SUPPORTS_LINKED_HASH_COLLECTIONS;
 private static final boolean JVM_HAS_TIMESTAMP_BUG;
 private static final boolean JVM_HAS_JDK14_TIMESTAMP;
 private static final boolean JVM_SUPPORTS_GET_GENERATED_KEYS;

 private static final Properties GLOBAL_PROPERTIES;
 private static final HashMap ISOLATION_LEVELS = new HashMap();
 private static final Map OBSOLETE_PROPERTIES = new HashMap();
 private static final Map RENAMED_PROPERTIES = new HashMap();

 private static final Log log = LogFactory.getLog(Environment.class);

 /**
  * Issues warnings to the user when any obsolete property names are used.
  */
 public static void verifyProperties(Properties props) {
  Iterator iter = props.keySet().iterator();
  Map propertiesToAdd = new HashMap();
  while ( iter.hasNext() ) {
   final Object propertyName = iter.next();
   Object newPropertyName = OBSOLETE_PROPERTIES.get( propertyName );
   if ( newPropertyName != null ) {
    log.warn( "Usage of obsolete property: " + propertyName + " no longer supported, use: " + newPropertyName );
   }
   newPropertyName = RENAMED_PROPERTIES.get( propertyName );
   if ( newPropertyName != null ) {
    log.warn( "Property [" + propertyName + "] has been renamed to [" + newPropertyName + "]; update your properties appropriately" );
    if ( ! props.containsKey( newPropertyName ) ) {
     propertiesToAdd.put( newPropertyName, props.get( propertyName ) );
    }
   }
  }
  props.putAll(propertiesToAdd);
 }

 static {

  log.info("Hibernate " + VERSION);

  RENAMED_PROPERTIES.put( "hibernate.cglib.use_reflection_optimizer", USE_REFLECTION_OPTIMIZER );

  ISOLATION_LEVELS.put( new Integer(Connection.TRANSACTION_NONE), "NONE" );
  ISOLATION_LEVELS.put( new Integer(Connection.TRANSACTION_READ_UNCOMMITTED), "READ_UNCOMMITTED" );
  ISOLATION_LEVELS.put( new Integer(Connection.TRANSACTION_READ_COMMITTED), "READ_COMMITTED" );
  ISOLATION_LEVELS.put( new Integer(Connection.TRANSACTION_REPEATABLE_READ), "REPEATABLE_READ" );
  ISOLATION_LEVELS.put( new Integer(Connection.TRANSACTION_SERIALIZABLE), "SERIALIZABLE" );

  GLOBAL_PROPERTIES = new Properties();
  //Set USE_REFLECTION_OPTIMIZER to false to fix HHH-227
  GLOBAL_PROPERTIES.setProperty( USE_REFLECTION_OPTIMIZER, Boolean.FALSE.toString() );

  try {
   InputStream stream = ConfigHelper.getResourceAsStream("/hibernate.properties");
   try {
    GLOBAL_PROPERTIES.load(stream);
    log.info( "loaded properties from resource hibernate.properties: " + PropertiesHelper.maskOut(GLOBAL_PROPERTIES, PASS) );
   }
   catch (Exception e) {
    log.error("problem loading properties from hibernate.properties");
   }
   finally {
    try{
     stream.close();
    }
    catch (IOException ioe){
     log.error("could not close stream on hibernate.properties", ioe);
    }
   }
  }
  catch (HibernateException he) {
   log.info("hibernate.properties not found");
  }

  try {
   GLOBAL_PROPERTIES.putAll( System.getProperties() );
  }
  catch (SecurityException se) {
   log.warn("could not copy system properties, system properties will be ignored");
  }

  verifyProperties(GLOBAL_PROPERTIES);

  ENABLE_BINARY_STREAMS = PropertiesHelper.getBoolean(USE_STREAMS_FOR_BINARY, GLOBAL_PROPERTIES);
  ENABLE_REFLECTION_OPTIMIZER = PropertiesHelper.getBoolean(USE_REFLECTION_OPTIMIZER, GLOBAL_PROPERTIES);

  if (ENABLE_BINARY_STREAMS) {
   log.info("using java.io streams to persist binary types");
  }
  if (ENABLE_REFLECTION_OPTIMIZER) {
   log.info("using bytecode reflection optimizer");
  }
  BYTECODE_PROVIDER_INSTANCE = buildBytecodeProvider( GLOBAL_PROPERTIES );

  boolean getGeneratedKeysSupport;
  try {
   Statement.class.getMethod("getGeneratedKeys", null);
   getGeneratedKeysSupport = true;
  }
  catch (NoSuchMethodException nsme) {
   getGeneratedKeysSupport = false;
  }
  JVM_SUPPORTS_GET_GENERATED_KEYS = getGeneratedKeysSupport;
  if (!JVM_SUPPORTS_GET_GENERATED_KEYS) log.info("JVM does not support Statement.getGeneratedKeys()");

  boolean linkedHashSupport;
  try {
   Class.forName("java.util.LinkedHashSet");
   linkedHashSupport = true;
  }
  catch (ClassNotFoundException cnfe) {
   linkedHashSupport = false;
  }
  JVM_SUPPORTS_LINKED_HASH_COLLECTIONS = linkedHashSupport;
  if (!JVM_SUPPORTS_LINKED_HASH_COLLECTIONS) log.info("JVM does not support LinkedHasMap, LinkedHashSet - ordered maps and sets disabled");

  JVM_HAS_TIMESTAMP_BUG = new Timestamp(123456789).getTime() != 123456789;
  if (JVM_HAS_TIMESTAMP_BUG) log.info("using workaround for JVM bug in java.sql.Timestamp");
  Timestamp t = new Timestamp(0);
  t.setNanos(5 * 1000000);
  JVM_HAS_JDK14_TIMESTAMP = t.getTime() == 5;
  if (JVM_HAS_JDK14_TIMESTAMP) {
   log.info("using JDK 1.4 java.sql.Timestamp handling");
  }
  else {
   log.info("using pre JDK 1.4 java.sql.Timestamp handling");
  }
 }

 public static BytecodeProvider getBytecodeProvider() {
  return BYTECODE_PROVIDER_INSTANCE;
 }

 /**
  * Does this JVM have the IBM JDK 1.3.1. The bug is <tt>new Timestamp(x).getTime()!=x</tt>.
  */
 public static boolean jvmHasTimestampBug() {
  return JVM_HAS_TIMESTAMP_BUG;
 }

 /**
  * Does this JVM handle <tt>Timestamp</tt> in the JDK 1.4 compliant way?
  */
 public static boolean jvmHasJDK14Timestamp() {
  return JVM_HAS_JDK14_TIMESTAMP;
 }

 /**
  * Does this JVM support <tt>LinkedHashSet</tt>, <tt>LinkedHashMap</tt>.
  * @see java.util.LinkedHashSet
  * @see java.util.LinkedHashMap
  */
 public static boolean jvmSupportsLinkedHashCollections() {
  return JVM_SUPPORTS_LINKED_HASH_COLLECTIONS;
 }

 public static boolean jvmSupportsGetGeneratedKeys() {
  return JVM_SUPPORTS_GET_GENERATED_KEYS;
 }

 /**
  * Should we use streams to bind binary types to JDBC IN parameters.
  * Property <tt>hibernate.jdbc.use_streams_for_binary</tt>.
  * @see Environment#USE_STREAMS_FOR_BINARY
  */
 public static boolean useStreamsForBinary() {
  return ENABLE_BINARY_STREAMS;
 }

 /**
  * Should we use CGLIB reflection optimizer.
  * Property <tt>hibernate.jdbc.use_refection_optimizer</tt>.
  * @see Environment#USE_REFLECTION_OPTIMIZER
  */
 public static boolean useReflectionOptimizer() {
  return ENABLE_REFLECTION_OPTIMIZER;
 }

 private Environment() { throw new UnsupportedOperationException(); }

 /**
  * Return <tt>System</tt> properties, extended by any properties specified
  * in <tt>hibernate.properties</tt>.
  * @return Properties
  */
 public static Properties getProperties() {
  Properties copy = new Properties();
  copy.putAll(GLOBAL_PROPERTIES);
  return copy;
 }

 /**
  * Get the name of a JDBC transaction isolation level
  *
  * @see java.sql.Connection
  * @param isolation as defined by <tt>java.sql.Connection</tt>
  * @return a human-readable name
  */
 public static String isolationLevelToString(int isolation) {
  return (String) ISOLATION_LEVELS.get( new Integer(isolation) );
 }

 public static BytecodeProvider buildBytecodeProvider(Properties properties) {
  String provider = PropertiesHelper.getString( Environment.BYTECODE_PROVIDER, properties, "cglib" );
  log.info( "Bytecode provider name : " + provider );
  return buildBytecodeProvider( provider );
 }

 private static BytecodeProvider buildBytecodeProvider(String providerName) {
  if ( "javassist".equals( providerName ) ) {
   return new org.hibernate.bytecode.javassist.BytecodeProviderImpl();
  }
  else if ( "cglib".equals( providerName ) ) {
   return new org.hibernate.bytecode.cglib.BytecodeProviderImpl();
  }
  else {
   log.warn( "unrecognized bytecode provider [" + providerName + "], using cglib by default" );
   return new org.hibernate.bytecode.cglib.BytecodeProviderImpl();
  }
 }

}