【Java开源代码栏目提醒】:网学会员为广大网友收集整理了,BlobFromLocator.java,希望对大家有所帮助!
/*
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.io.ByteArrayInputStream;
import java.io.OutputStream;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
/**
* The representation (mapping) in the
JavaTM programming language of an SQL
* BLOB value. An SQL BLOB is a built-in type that stores a Binary Large Object
* as a column value in a row of a database table. The driver implements Blob
* using an SQL locator(BLOB), which means that a Blob object contains a logical
* pointer to the SQL BLOB data rather than the data itself. A Blob object is
* valid for the duration of the transaction in which is was created. Methods in
* the interfaces ResultSet, CallableStatement, and PreparedStatement, such as
* getBlob and setBlob allow a programmer to access an SQL BLOB value. The Blob
* interface provides methods for getting the length of an SQL BLOB (Binary
* Large Object) value, for materializing a BLOB value on the client, and for
* determining the position of a pattern of bytes within a BLOB value. This
* class is new in the JDBC 2.0 API.
*
* @author Mark Matthews
*
* @version $Id: BlobFromLocator.java,v 1.1.2.1 2005/05/13 18:58:38 mmatthews
* Exp $
*/
public class BlobFromLocator implements java.sql.Blob {
private String blobColumnName = null;
/** The ResultSet that created this BLOB */
private ResultSet creatorResultSet;
private int numColsInResultSet = 0;
private int numPrimaryKeys = 0;
private List primaryKeyColumns = null;
private List primaryKeyValues = null;
private String quotedId;
private String tableName = null;
/**
* Creates an updatable BLOB that can update in-place
*/
BlobFromLocator(ResultSet creatorResultSetToSet, int blobColumnIndex)
throws SQLException {
this.creatorResultSet = creatorResultSetToSet;
this.numColsInResultSet = this.creatorResultSet.fields.length;
this.quotedId = this.creatorResultSet.connection.getMetaData()
.getIdentifierQuoteString();
if (this.numColsInResultSet > 1) {
this.primaryKeyColumns = new ArrayList();
this.primaryKeyValues = new ArrayList();
for (int i = 0; i < this.numColsInResultSet; i++) {
if (this.creatorResultSet.fields[i].isPrimaryKey()) {
StringBuffer keyName = new StringBuffer();
keyName.append(quotedId);
String originalColumnName = this.creatorResultSet.fields[i]
.getOriginalName();
if (this.creatorResultSet.connection.getIO()
.hasLongColumnInfo()
&& (originalColumnName != null)
&& (originalColumnName.length() > 0)) {
keyName.append(originalColumnName);
} else {
keyName.append(this.creatorResultSet.fields[i]
.getName());
}
keyName.append(quotedId);
this.primaryKeyColumns.add(keyName.toString());
this.primaryKeyValues.add(this.creatorResultSet
.getString(i + 1));
}
}
} else {
notEnoughInformationInQuery();
}
this.numPrimaryKeys = this.primaryKeyColumns.size();
if (this.numPrimaryKeys == 0) {
notEnoughInformationInQuery();
}
if (this.creatorResultSet.fields[0].getOriginalTableName() != null) {
StringBuffer tableNameBuffer = new StringBuffer();
String databaseName = this.creatorResultSet.fields[0]
.getDatabaseName();
if ((databaseName != null) && (databaseName.length() > 0)) {
tableNameBuffer.append(quotedId);
tableNameBuffer.append(databaseName);
tableNameBuffer.append(quotedId);
tableNameBuffer.append('.');
}
tableNameBuffer.append(quotedId);
tableNameBuffer.append(this.creatorResultSet.fields[0]
.getOriginalTableName());
tableNameBuffer.append(q