resultsetmetadata.java

mysql的jdbc驱动

/*
 Copyright (C) 2002-2004 MySQL AB

 This program is free software; you can redistribute it and/or modify
 it under the terms of version 2 of the GNU General Public License as 
 published by the Free Software Foundation.

 There are special exceptions to the terms and conditions of the GPL 
 as it is applied to this software. View the full text of the 
 exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
 software distribution.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



 */
package com.mysql.jdbc;

import java.sql.SQLException;
import java.sql.Types;

/**
 * A ResultSetMetaData object can be used to find out about the types and
 * properties of the columns in a ResultSet
 * 
 * @author Mark Matthews
 * @version $Id: ResultSetMetaData.java,v 1.1.2.1 2005/05/13 18:58:38 mmatthews
 *          Exp $
 * 
 * @see java.sql.ResultSetMetaData
 */
public class ResultSetMetaData implements java.sql.ResultSetMetaData {
	private static int clampedGetLength(Field f) {
		long fieldLength = f.getLength();

		if (fieldLength > Integer.MAX_VALUE) {
			fieldLength = Integer.MAX_VALUE;
		}

		return (int) fieldLength;
	}

	/**
	 * Checks if the SQL Type is a Decimal/Number Type
	 * 
	 * @param type
	 *            SQL Type
	 * 
	 * @return ...
	 */
	private static final boolean isDecimalType(int type) {
		switch (type) {
		case Types.BIT:
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.NUMERIC:
		case Types.DECIMAL:
			return true;
		}

		return false;
	}

	Field[] fields;

	/**
	 * Initialise for a result with a tuple set and a field descriptor set
	 * 
	 * @param fields
	 *            the array of field descriptors
	 */
	public ResultSetMetaData(Field[] fields) {
		this.fields = fields;
	}

	/**
	 * What's a column's table's catalog name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return catalog name, or "" if not applicable
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getCatalogName(int column) throws SQLException {
		Field f = getField(column);

		String database = f.getDatabaseName();

		return (database == null) ? "" : database; //$NON-NLS-1$
	}

	/**
	 * What's the Java character encoding name for the given column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the Java character encoding name for the given column, or null if
	 *         no Java character encoding maps to the MySQL character set for
	 *         the given column.
	 * 
	 * @throws SQLException
	 *             if an invalid column index is given.
	 */
	public String getColumnCharacterEncoding(int column) throws SQLException {
		String mysqlName = getColumnCharacterSet(column);

		String javaName = null;

		if (mysqlName != null) {
			javaName = CharsetMapping.getJavaEncodingForMysqlEncoding(
					mysqlName, null);
		}

		return javaName;
	}

	/**
	 * What's the MySQL character set name for the given column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the MySQL character set name for the given column
	 * 
	 * @throws SQLException
	 *             if an invalid column index is given.
	 */
	public String getColumnCharacterSet(int column) throws SQLException {
		return getField(column).getCharacterSet();
	}

	// --------------------------JDBC 2.0-----------------------------------

	/**
	 * JDBC 2.0
	 * 
	 * <p>
	 * Return the fully qualified name of the Java class whose instances are
	 * manufactured if ResultSet.getObject() is called to retrieve a value from
	 * the column. ResultSet.getObject() may return a subClass of the class
	 * returned by this method.
	 * </p>
	 * 
	 * @param column
	 *            the column number to retrieve information for
	 * 
	 * @return the fully qualified name of the Java class whose instances are
	 *         manufactured if ResultSet.getObject() is called to retrieve a
	 *         value from the column.
	 * 
	 * @throws SQLException
	 *             if an error occurs
	 */
	public String getColumnClassName(int column) throws SQLException {
		Field f = getField(column);

		// From JDBC-3.0 spec, Table B-3
		//
		// JDBC Type Java Object Type
		//
		// CHAR String
		// VARCHAR String
		// LONGVARCHAR String
		// NUMERIC java.math.BigDecimal
		// DECIMAL java.math.BigDecimal
		// BIT Boolean
		// BOOLEAN Boolean
		// TINYINT Integer
		// SMALLINT Integer
		// INTEGER Integer
		// BIGINT Long
		// REAL Float
		// FLOAT Double
		// DOUBLE Double
		// BINARY byte[]
		// VARBINARY byte[]
		// LONGVARBINARY byte[]
		// DATE java.sql.Date
		// TIME java.sql.Time
		// TIMESTAMP java.sql.Timestamp
		// DISTINCT Object type of underlying type
		// CLOB Clob
		// BLOB Blob
		// ARRAY Array
		// STRUCT Struct or SQLData
		// REF Ref
		// DATALINK java.net.URL
		// JAVA_OBJECT underlying Java class
		switch (f.getSQLType()) {
		case Types.BIT:
		case Types.BOOLEAN:
			return "java.lang.Boolean"; //$NON-NLS-1$

		case Types.TINYINT:

			if (!f.isUnsigned()) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Integer"; //$NON-NLS-1$

		case Types.SMALLINT:

			if (!f.isUnsigned()) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Integer"; //$NON-NLS-1$

		case Types.INTEGER:

			if (!f.isUnsigned()) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Long"; //$NON-NLS-1$

		case Types.BIGINT:

			if (!f.isUnsigned()) {
				return "java.lang.Long"; //$NON-NLS-1$
			}

			return "java.math.BigInteger"; //$NON-NLS-1$

		case Types.DECIMAL:
		case Types.NUMERIC:
			return "java.math.BigDecimal"; //$NON-NLS-1$

		case Types.REAL:
			return "java.lang.Float"; //$NON-NLS-1$

		case Types.FLOAT:
		case Types.DOUBLE:
			return "java.lang.Double"; //$NON-NLS-1$

		case Types.CHAR:
		case Types.VARCHAR:
		case Types.LONGVARCHAR:
			if (!f.isOpaqueBinary()) {
				return "java.lang.String"; //$NON-NLS-1$
			}

			return "[B";

		case Types.BINARY:
		case Types.VARBINARY:
		case Types.LONGVARBINARY:

			if (f.getMysqlType() == MysqlDefs.FIELD_TYPE_GEOMETRY) {
				return "[B";
			} else if (f.isBinary() || f.isBlob()) {
				return "[B";
			} else {
				return "java.lang.String";
			}

		case Types.DATE:
			return "java.sql.Date"; //$NON-NLS-1$

		case Types.TIME:
			return "java.sql.Time"; //$NON-NLS-1$

		case Types.TIMESTAMP:
			return "java.sql.Timestamp"; //$NON-NLS-1$

		default:
			return "java.lang.Object"; //$NON-NLS-1$
		}
	}

	/**
	 * Whats the number of columns in the ResultSet?
	 * 
	 * @return the number
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getColumnCount() throws SQLException {
		return this.fields.length;
	}

	/**
	 * What is the column's normal maximum width in characters?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the maximum width
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getColumnDisplaySize(int column) throws SQLException {
		Field f = getField(column);

		int lengthInBytes = clampedGetLength(f);

		return lengthInBytes / f.getMaxBytesPerCharacter();
	}

	/**
	 * What is the suggested column title for use in printouts and displays?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the column label
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getColumnLabel(int column) throws SQLException {
		return getColumnName(column);
	}

	/**
	 * What's a column's name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the column name
	 * 
	 * @throws SQLException
	 *             if a databvase access error occurs
	 */
	public String getColumnName(int column) throws SQLException {
		return getField(column).getName();
	}

	/**
	 * What is a column's SQL Type? (java.sql.Type int)
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the java.sql.Type value
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 * 
	 * @see java.sql.Types
	 */
	public int getColumnType(int column) throws SQLException {
		return getField(column).getSQLType();
	}

	/**
	 * Whats is the column's data source specific type name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the type name
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getColumnTypeName(int column) throws java.sql.SQLException {
		Field field = getField(column);

		int mysqlType = field.getMysqlType();

		switch (mysqlType) {
		case MysqlDefs.FIELD_TYPE_BIT:
			return "BIT";
		case MysqlDefs.FIELD_TYPE_DECIMAL:
		case MysqlDefs.FIELD_TYPE_NEW_DECIMAL:
			return field.isUnsigned() ? "DECIMAL UNSIGNED" : "DECIMAL";

		case MysqlDefs.FIELD_TYPE_TINY:
			return field.isUnsigned() ? "TINYINT UNSIGNED" : "TINYINT";

		case MysqlDefs.FIELD_TYPE_SHORT:
			return field.isUnsigned() ? "SMALLINT UNSIGNED" : "SMALLINT";

		case MysqlDefs.FIELD_TYPE_LONG:
			return field.isUnsigned() ? "INTEGER UNSIGNED" : "INTEGER";

		case MysqlDefs.FIELD_TYPE_FLOAT:
			return field.isUnsigned() ? "FLOAT UNSIGNED" : "FLOAT";

		case MysqlDefs.FIELD_TYPE_DOUBLE: