resultsetmetadata.java

mysql 5.1的 jdbc驱动 Connector/J 5.1 支持Mysql 4.1、Mysql 5.0、Mysql 5.1、Mysql 6.0 alpha这些版本。 Connector/J

		switch (f.getMysqlType()) {
		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
		case MysqlDefs.FIELD_TYPE_BLOB:
		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			return clampedGetLength(f); // this may change in the future
		// for now, the server only
		// returns FIELD_TYPE_BLOB for _all_
		// BLOB types, but varying lengths
		// indicating the _maximum_ size
		// for each BLOB type.
		default:
			return clampedGetLength(f) / f.getMaxBytesPerCharacter();

		}
	}

	/**
	 * What is a column's number of digits to the right of the decimal point?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the scale
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getScale(int column) throws SQLException {
		Field f = getField(column);

		if (isDecimalType(f.getSQLType())) {
			return f.getDecimals();
		}

		return 0;
	}

	/**
	 * What is a column's table's schema? This relies on us knowing the table
	 * name. The JDBC specification allows us to return "" if this is not
	 * applicable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the Schema
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getSchemaName(int column) throws SQLException {
		return ""; //$NON-NLS-1$
	}

	/**
	 * Whats a column's table's name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return column name, or "" if not applicable
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getTableName(int column) throws SQLException {
		if (this.useOldAliasBehavior) {
			return getField(column).getTableName();
		}
		
		return getField(column).getTableNameNoAliases();
	}

	/**
	 * Is the column automatically numbered (and thus read-only)
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isAutoIncrement(int column) throws SQLException {
		Field f = getField(column);

		return f.isAutoIncrement();
	}

	/**
	 * Does a column's case matter?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws java.sql.SQLException
	 *             if a database access error occurs
	 */
	public boolean isCaseSensitive(int column) throws java.sql.SQLException {
		Field field = getField(column);

		int sqlType = field.getSQLType();

		switch (sqlType) {
		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.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		case Types.CHAR:
		case Types.VARCHAR:
		case Types.LONGVARCHAR:

			if (field.isBinary()) {
				return true;
			}

			String collationName = field.getCollation();

			return ((collationName != null) && !collationName.endsWith("_ci"));

		default:
			return true;
		}
	}

	/**
	 * Is the column a cash value?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if its a cash column
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isCurrency(int column) throws SQLException {
		return false;
	}

	/**
	 * Will a write on this column definately succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc..
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isDefinitelyWritable(int column) throws SQLException {
		return isWritable(column);
	}

	/**
	 * Can you put a NULL in this column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return one of the columnNullable values
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int isNullable(int column) throws SQLException {
		if (!getField(column).isNotNull()) {
			return java.sql.ResultSetMetaData.columnNullable;
		}

		return java.sql.ResultSetMetaData.columnNoNulls;
	}

	/**
	 * Is the column definitely not writable?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isReadOnly(int column) throws SQLException {
		return getField(column).isReadOnly();
	}

	/**
	 * Can the column be used in a WHERE clause? Basically for this, I split the
	 * functions into two types: recognised types (which are always useable),
	 * and OTHER types (which may or may not be useable). The OTHER types, for
	 * now, I will assume they are useable. We should really query the catalog
	 * to see if they are useable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if they can be used in a WHERE clause
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSearchable(int column) throws SQLException {
		return true;
	}

	/**
	 * Is the column a signed number?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSigned(int column) throws SQLException {
		Field f = getField(column);
		int sqlType = f.getSQLType();

		switch (sqlType) {
		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 !f.isUnsigned();

		case Types.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		default:
			return false;
		}
	}

	/**
	 * Is it possible for a write on the column to succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isWritable(int column) throws SQLException {
		return !isReadOnly(column);
	}

	/**
	 * Returns a string representation of this object
	 * 
	 * @return ...
	 */
	public String toString() {
		StringBuffer toStringBuf = new StringBuffer();
		toStringBuf.append(super.toString());
		toStringBuf.append(" - Field level information: "); //$NON-NLS-1$

		for (int i = 0; i < this.fields.length; i++) {
			toStringBuf.append("\n\t"); //$NON-NLS-1$
			toStringBuf.append(this.fields[i].toString());
		}

		return toStringBuf.toString();
	}
	
	static String getClassNameForJavaType(int javaType, 
			boolean isUnsigned, int mysqlTypeIfKnown, 
			boolean isBinaryOrBlob,
			boolean isOpaqueBinary) {
		switch (javaType) {
		case Types.BIT:
		case Types.BOOLEAN:
			return "java.lang.Boolean"; //$NON-NLS-1$

		case Types.TINYINT:

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

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

		case Types.SMALLINT:

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

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

		case Types.INTEGER:

			if (!isUnsigned || 
					mysqlTypeIfKnown == MysqlDefs.FIELD_TYPE_INT24) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

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

		case Types.BIGINT:

			if (!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 (!isOpaqueBinary) {
				return "java.lang.String"; //$NON-NLS-1$
			}

			return "[B";

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

			if (mysqlTypeIfKnown == MysqlDefs.FIELD_TYPE_GEOMETRY) {
				return "[B";
			} else if (isBinaryOrBlob) {
				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"; //$NON-NLS-1$
		}
	}
	
	/**
     * Returns true if this either implements the interface argument or is directly or indirectly a wrapper
     * for an object that does. Returns false otherwise. If this implements the interface then return true,
     * else if this is a wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped
     * object. If this does not implement the interface and is not a wrapper, return false.
     * This method should be implemented as a low-cost operation compared to <code>unwrap</code> so that
     * callers can use this method to avoid expensive <code>unwrap</code> calls that may fail. If this method
     * returns true then calling <code>unwrap</code> with the same argument should succeed.
     *
     * @param interfaces a Class defining an interface.
     * @return true if this implements the interface or directly or indirectly wraps an object that does.
     * @throws java.sql.SQLException  if an error occurs while determining whether this is a wrapper
     * for an object with the given interface.
     * @since 1.6
     */
	public boolean isWrapperFor(Class iface) throws SQLException {
		// This works for classes that aren't actually wrapping
		// anything
		return iface.isInstance(this);
	}

    /**
     * Returns an object that implements the given interface to allow access to non-standard methods,
     * or standard methods not exposed by the proxy.
     * The result may be either the object found to implement the interface or a proxy for that object.
     * If the receiver implements the interface then that is the object. If the receiver is a wrapper
     * and the wrapped object implements the interface then that is the object. Otherwise the object is
     *  the result of calling <code>unwrap</code> recursively on the wrapped object. If the receiver is not a
     * wrapper and does not implement the interface, then an <code>SQLException</code> is thrown.
     *
     * @param iface A Class defining an interface that the result must implement.
     * @return an object that implements the interface. May be a proxy for the actual implementing object.
     * @throws java.sql.SQLException If no object found that implements the interface 
     * @since 1.6
     */
	public Object unwrap(Class iface) throws java.sql.SQLException {
    	try {
    		// This works for classes that aren't actually wrapping
    		// anything
    		return Util.cast(iface, this);
        } catch (ClassCastException cce) {
            throw SQLError.createSQLException("Unable to unwrap to " + iface.toString(), 
            		SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
        }
    }
}