dialect.java

介绍了hibernate的入门有一些基本常用的事例

//$Id: Dialect.java,v 1.36 2005/04/11 12:39:50 maxcsaucdk Exp $
package org.hibernate.dialect;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.LockMode;
import org.hibernate.MappingException;
import org.hibernate.QueryException;
import org.hibernate.cfg.Environment;
import org.hibernate.dialect.function.SQLFunction;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.engine.Mapping;
import org.hibernate.exception.SQLExceptionConverter;
import org.hibernate.exception.SQLStateConverter;
import org.hibernate.exception.ViolatedConstraintNameExtracter;
import org.hibernate.id.IdentityGenerator;
import org.hibernate.id.SequenceGenerator;
import org.hibernate.id.TableHiLoGenerator;
import org.hibernate.sql.ANSICaseFragment;
import org.hibernate.sql.ANSIJoinFragment;
import org.hibernate.sql.CaseFragment;
import org.hibernate.sql.JoinFragment;
import org.hibernate.type.Type;
import org.hibernate.util.ReflectHelper;
import org.hibernate.util.StringHelper;

import java.sql.CallableStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

/**
 * Represents a dialect of SQL implemented by a particular RDBMS.
 * Subclasses implement Hibernate compatibility with different systems.<br>
 * <br>
 * Subclasses should provide a public default constructor that <tt>register()</tt>
 * a set of type mappings and default Hibernate properties.<br>
 * <br>
 * Subclasses should be immutable.
 *
 * @author Gavin King, David Channon
 */
public abstract class Dialect {

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

	static final String DEFAULT_BATCH_SIZE = "15";
	static final String NO_BATCH = "0";

	private static final Map STANDARD_AGGREGATE_FUNCTIONS = new HashMap();

	static {
		STANDARD_AGGREGATE_FUNCTIONS.put( "count", new StandardSQLFunction("count") {
			public Type getReturnType(Type columnType, Mapping mapping) {
				return Hibernate.INTEGER;
			}
		} );

		STANDARD_AGGREGATE_FUNCTIONS.put( "avg", new StandardSQLFunction("avg") {
			public Type getReturnType(Type columnType, Mapping mapping) throws QueryException {
				int[] sqlTypes;
				try {
					sqlTypes = columnType.sqlTypes( mapping );
				}
				catch ( MappingException me ) {
					throw new QueryException( me );
				}
				if ( sqlTypes.length != 1 ) throw new QueryException( "multi-column type in avg()" );
				int sqlType = sqlTypes[0];
				if ( sqlType == Types.INTEGER || sqlType == Types.BIGINT || sqlType == Types.TINYINT ) {
					return Hibernate.FLOAT;
				}
				else {
					return columnType;
				}
			}
		} );

		STANDARD_AGGREGATE_FUNCTIONS.put( "max", new StandardSQLFunction("max") );
		STANDARD_AGGREGATE_FUNCTIONS.put( "min", new StandardSQLFunction("min") );
		STANDARD_AGGREGATE_FUNCTIONS.put( "sum", new StandardSQLFunction("sum") );
	}

	protected Dialect() {
		log.info( "Using dialect: " + this );
		sqlFunctions.putAll( STANDARD_AGGREGATE_FUNCTIONS );

		// standard sql92 functions
		registerFunction( "substring", new SQLFunctionTemplate( Hibernate.STRING, "substring(?1, ?2, ?3)" ) );
		registerFunction( "length", new SQLFunctionTemplate( Hibernate.INTEGER, "length(?1)" ) );
		registerFunction( "locate", new SQLFunctionTemplate( Hibernate.INTEGER, "locate(?1, ?2, ?3)" ) );
		registerFunction( "abs", new SQLFunctionTemplate( Hibernate.DOUBLE, "abs(?1)" ) );
		registerFunction( "sqrt", new SQLFunctionTemplate( Hibernate.DOUBLE, "sqrt(?1)" ) );
		registerFunction( "trim", new SQLFunctionTemplate( Hibernate.STRING, "trim(?1 ?2 ?3 ?4)" ) );
		registerFunction( "bit_length", new SQLFunctionTemplate( Hibernate.INTEGER, "BIT_LENGTH(?1)" ) );
	}

	public String toString() {
		return getClass().getName();
	}

	private final TypeNames typeNames = new TypeNames();
	private final Properties properties = new Properties();
	private final Map sqlFunctions = new HashMap();

	/**
	 * Characters used for quoting SQL identifiers
	 */
	public static final String QUOTE = "`\"[";
	public static final String CLOSED_QUOTE = "`\"]";


	/**
	 * Get the name of the database type associated with the given
	 * <tt>java.sql.Types</tt> typecode.
	 *
	 * @param code <tt>java.sql.Types</tt> typecode
	 * @return the database type name
	 * @throws HibernateException
	 */
	public String getTypeName(int code) throws HibernateException {
		String result = typeNames.get( code );
		if ( result == null ) {
			throw new HibernateException( "No default type mapping for (java.sql.Types) " + code );
		}
		return result;
	}

	/**
	 * Get the name of the database type associated with the given
	 * <tt>java.sql.Types</tt> typecode.
	 * @param code      <tt>java.sql.Types</tt> typecode
	 * @param length    the length or precision of the column
	 * @param precision the precision of the column
	 * @param scale the scale of the column
	 *
	 * @return the database type name
	 * @throws HibernateException
	 */
	public String getTypeName(int code, int length, int precision, int scale) throws HibernateException {
		String result = typeNames.get( code, length, precision, scale );
		if ( result == null ) {
			throw new HibernateException( "No type mapping for java.sql.Types code: " +
					code +
					", length: " +
					length );
		}
		return result;
	}

	protected void registerFunction(String name, SQLFunction function) {
		sqlFunctions.put( name, function );
	}

	/**
	 * Subclasses register a typename for the given type code and maximum
	 * column length. <tt>$l</tt> in the type name with be replaced by the
	 * column length (if appropriate).
	 *
	 * @param code     <tt>java.sql.Types</tt> typecode
	 * @param capacity maximum length of database type
	 * @param name     the database type name
	 */
	protected void registerColumnType(int code, int capacity, String name) {
		typeNames.put( code, capacity, name );
	}

	/**
	 * Subclasses register a typename for the given type code. <tt>$l</tt> in
	 * the type name with be replaced by the column length (if appropriate).
	 *
	 * @param code <tt>java.sql.Types</tt> typecode
	 * @param name the database type name
	 */
	protected void registerColumnType(int code, String name) {
		typeNames.put( code, name );
	}

	/**
	 * Does this dialect support the <tt>ALTER TABLE</tt> syntax?
	 *
	 * @return boolean
	 */
	public boolean hasAlterTable() {
		return true;
	}

	/**
	 * Do we need to drop constraints before dropping tables in this dialect?
	 *
	 * @return boolean
	 */
	public boolean dropConstraints() {
		return true;
	}

	/**
	 * Do we need to qualify index names with the schema name?
	 *
	 * @return boolean
	 */
	public boolean qualifyIndexName() {
		return true;
	}

	/**
	 * Does the <tt>FOR UPDATE OF</tt> syntax specify particular
	 * columns?
	 */
	public boolean forUpdateOfColumns() {
		return false;
	}

	/**
	 * Does this dialect support the <tt>FOR UPDATE OF</tt> syntax?
	 *
	 * @return boolean
	 */
	public String getForUpdateString(String aliases) {
		return getForUpdateString();
	}

	/**
	 * Does this dialect support the Oracle-style <tt>FOR UPDATE OF ... NOWAIT</tt>
	 * syntax?
	 *
	 * @return boolean
	 */
	public String getForUpdateNowaitString(String aliases) {
		return getForUpdateString( aliases );
	}

	/**
	 * Does this dialect support the <tt>FOR UPDATE</tt> syntax?
	 *
	 * @return boolean
	 */
	public String getForUpdateString() {
		return " for update";
	}

	/**
	 * Does this dialect support the Oracle-style <tt>FOR UPDATE NOWAIT</tt> syntax?
	 *
	 * @return boolean
	 */
	public String getForUpdateNowaitString() {
		return getForUpdateString();
	}

	/**
	 * Does this dialect support the <tt>UNIQUE</tt> column syntax?
	 *
	 * @return boolean
	 */
	public boolean supportsUnique() {
		return true;
	}
	

    /**
     * Does this dialect support adding Unique constraints via create and alter table ?
     * @return boolean
     */
	public boolean supportsUniqueConstraintInCreateAlterTable() {
	    return true;
	}


	/**
	 * The syntax used to add a column to a table (optional).
	 */
	public String getAddColumnString() {
		throw new UnsupportedOperationException( "No add column syntax supported by Dialect" );
	}

	public String getDropForeignKeyString() {
		return " drop constraint ";
	}

	public String getTableTypeString() {
		return "";
	}

	/**
	 * The syntax used to add a foreign key constraint to a table.
	 *
	 * @return String
	 */
	public String getAddForeignKeyConstraintString(String constraintName,
												   String[] foreignKey,
												   String referencedTable,
												   String[] primaryKey) {
		return new StringBuffer( 30 )
				.append( " add constraint " )
				.append( constraintName )
				.append( " foreign key (" )
				.append( StringHelper.join( ", ", foreignKey ) )
				.append( ") references " )
				.append( referencedTable )
				.toString();
	}

	/**
	 * The syntax used to add a primary key constraint to a table.
	 *
	 * @return String
	 */
	public String getAddPrimaryKeyConstraintString(String constraintName) {
		return " add constraint " + constraintName + " primary key ";
	}

	/**
	 * The keyword used to specify a nullable column.
	 *
	 * @return String
	 */
	public String getNullColumnString() {
		return "";
	}

	/**
	 * Does this dialect support identity column key generation?
	 *
	 * @return boolean
	 */
	public boolean supportsIdentityColumns() {
		return false;
	}

	/**
	 * Does this dialect support sequences?
	 *
	 * @return boolean
	 */
	public boolean supportsSequences() {
		return false;
	}

	public boolean supportsInsertSelectIdentity() {
		return false;
	}

	/**
	 * Append a clause to retrieve the generated identity value for the
	 * given <tt>INSERT</tt> statement.
	 */
	public String appendIdentitySelectToInsert(String insertString) {
		return insertString;
	}

	protected String getIdentitySelectString() throws MappingException {
		throw new MappingException( "Dialect does not support identity key generation" );
	}

	/**
	 * The syntax that returns the identity value of the last insert, if
	 * identity column key generation is supported.
	 *
	 * @param type TODO
	 * @throws MappingException if no native key generation
	 */
	public String getIdentitySelectString(String table, String column, int type)
			throws MappingException {
		return getIdentitySelectString();
	}

	protected String getIdentityColumnString() throws MappingException {
		throw new MappingException( "Dialect does not support identity key generation" );
	}

	/**
	 * The keyword used to specify an identity column, if identity
	 * column key generation is supported.
	 *
	 * @param type the SQL column type, as defined by <tt>java.sql.Types</tt>
	 * @throws MappingException if no native key generation
	 */
	public String getIdentityColumnString(int type) throws MappingException {
		return getIdentityColumnString();
	}

	/**
	 * The keyword used to insert a generated value into an identity column (or null)
	 *
	 * @return String
	 */
	public String getIdentityInsertString() {