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BlobFromLocator.java

/*
 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.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.mysql.jdbc.exceptions.NotYetImplementedException;

/**
 * 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 1.1.4.1 2005/05/19 18:31:49 mmatthews
 *          Exp $
 */
00056 public class BlobFromLocator implements java.sql.Blob {
      private List primaryKeyColumns = null;

      private List primaryKeyValues = null;

      /** The ResultSet that created this BLOB */
00062       private ResultSetImpl creatorResultSet;

      private String blobColumnName = null;

      private String tableName = null;

      private int numColsInResultSet = 0;

      private int numPrimaryKeys = 0;

      private String quotedId;

      /**
       * Creates an updatable BLOB that can update in-place
       */
00077       BlobFromLocator(ResultSetImpl 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 ((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(quotedId);

                  this.tableName = tableNameBuffer.toString();
            } else {
                  StringBuffer tableNameBuffer = new StringBuffer();

                  tableNameBuffer.append(quotedId);
                  tableNameBuffer.append(this.creatorResultSet.fields[0]
                              .getTableName());
                  tableNameBuffer.append(quotedId);

                  this.tableName = tableNameBuffer.toString();
            }

            this.blobColumnName = quotedId
                        + this.creatorResultSet.getString(blobColumnIndex) + quotedId;
      }

      private void notEnoughInformationInQuery() throws SQLException {
            throw SQLError.createSQLException("Emulated BLOB locators must come from "
                        + "a ResultSet with only one table selected, and all primary "
                        + "keys selected", SQLError.SQL_STATE_GENERAL_ERROR);
      }

      /**
       * @see Blob#setBinaryStream(long)
       */
00165       public OutputStream setBinaryStream(long indexToWriteAt)
                  throws SQLException {
            throw new NotImplemented();
      }

      /**
       * Retrieves the BLOB designated by this Blob instance as a stream.
       * 
       * @return this BLOB represented as a binary stream of bytes.
       * 
       * @throws SQLException
       *             if a database error occurs
       */
00178       public java.io.InputStream getBinaryStream() throws SQLException {
            // TODO: Make fetch size configurable
            return new BufferedInputStream(new LocatorInputStream(),
                        this.creatorResultSet.connection.getLocatorFetchBufferSize());
      }

      /**
       * @see Blob#setBytes(long, byte[], int, int)
       */
00187       public int setBytes(long writeAt, byte[] bytes, int offset, int length)
                  throws SQLException {
            java.sql.PreparedStatement pStmt = null;

            if ((offset + length) > bytes.length) {
                  length = bytes.length - offset;
            }

            byte[] bytesToWrite = new byte[length];
            System.arraycopy(bytes, offset, bytesToWrite, 0, length);

            // FIXME: Needs to use identifiers for column/table names
            StringBuffer query = new StringBuffer("UPDATE ");
            query.append(this.tableName);
            query.append(" SET ");
            query.append(this.blobColumnName);
            query.append(" = INSERT(");
            query.append(this.blobColumnName);
            query.append(", ");
            query.append(writeAt);
            query.append(", ");
            query.append(length);
            query.append(", ?) WHERE ");

            query.append((String) this.primaryKeyColumns.get(0));
            query.append(" = ?");

            for (int i = 1; i < this.numPrimaryKeys; i++) {
                  query.append(" AND ");
                  query.append((String) this.primaryKeyColumns.get(i));
                  query.append(" = ?");
            }

            try {
                  // FIXME: Have this passed in instead
                  pStmt = this.creatorResultSet.connection.prepareStatement(query
                              .toString());

                  pStmt.setBytes(1, bytesToWrite);

                  for (int i = 0; i < this.numPrimaryKeys; i++) {
                        pStmt.setString(i + 2, (String) this.primaryKeyValues.get(i));
                  }

                  int rowsUpdated = pStmt.executeUpdate();

                  if (rowsUpdated != 1) {
                        throw SQLError.createSQLException(
                                    "BLOB data not found! Did primary keys change?",
                                    SQLError.SQL_STATE_GENERAL_ERROR);
                  }
            } finally {
                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        pStmt = null;
                  }
            }

            return (int) length();
      }

      /**
       * @see Blob#setBytes(long, byte[])
       */
00256       public int setBytes(long writeAt, byte[] bytes) throws SQLException {
            return setBytes(writeAt, bytes, 0, bytes.length);
      }

      /**
       * Returns as an array of bytes, part or all of the BLOB value that this
       * Blob object designates.
       * 
       * @param pos
       *            where to start the part of the BLOB
       * @param length
       *            the length of the part of the BLOB you want returned.
       * 
       * @return the bytes stored in the blob starting at position
       *         <code>pos</code> and having a length of <code>length</code>.
       * 
       * @throws SQLException
       *             if a database error occurs
       */
00275       public byte[] getBytes(long pos, int length) throws SQLException {
            java.sql.PreparedStatement pStmt = null;

            try {

                  pStmt = createGetBytesStatement();

                  return getBytesInternal(pStmt, pos, length);
            } finally {
                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        pStmt = null;
                  }
            }
      }
      
      /**
       * Returns the number of bytes in the BLOB value designated by this Blob
       * object.
       * 
       * @return the length of this blob
       * 
       * @throws SQLException
       *             if a database error occurs
       */
00305       public long length() throws SQLException {
            java.sql.ResultSet blobRs = null;
            java.sql.PreparedStatement pStmt = null;

            // FIXME: Needs to use identifiers for column/table names
            StringBuffer query = new StringBuffer("SELECT LENGTH(");
            query.append(this.blobColumnName);
            query.append(") FROM ");
            query.append(this.tableName);
            query.append(" WHERE ");

            query.append((String) this.primaryKeyColumns.get(0));
            query.append(" = ?");

            for (int i = 1; i < this.numPrimaryKeys; i++) {
                  query.append(" AND ");
                  query.append((String) this.primaryKeyColumns.get(i));
                  query.append(" = ?");
            }

            try {
                  // FIXME: Have this passed in instead
                  pStmt = this.creatorResultSet.connection.prepareStatement(query
                              .toString());

                  for (int i = 0; i < this.numPrimaryKeys; i++) {
                        pStmt.setString(i + 1, (String) this.primaryKeyValues.get(i));
                  }

                  blobRs = pStmt.executeQuery();

                  if (blobRs.next()) {
                        return blobRs.getLong(1);
                  }

                  throw SQLError.createSQLException(
                              "BLOB data not found! Did primary keys change?",
                              SQLError.SQL_STATE_GENERAL_ERROR);
            } finally {
                  if (blobRs != null) {
                        try {
                              blobRs.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        blobRs = null;
                  }

                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        pStmt = null;
                  }
            }
      }

      /**
       * Finds the position of the given pattern in this BLOB.
       * 
       * @param pattern
       *            the pattern to find
       * @param start
       *            where to start finding the pattern
       * 
       * @return the position where the pattern is found in the BLOB, -1 if not
       *         found
       * 
       * @throws SQLException
       *             if a database error occurs
       */
00380       public long position(java.sql.Blob pattern, long start) throws SQLException {
            return position(pattern.getBytes(0, (int) pattern.length()), start);
      }

      /**
       * @see java.sql.Blob#position(byte[], long)
       */
00387       public long position(byte[] pattern, long start) throws SQLException {
            java.sql.ResultSet blobRs = null;
            java.sql.PreparedStatement pStmt = null;

            // FIXME: Needs to use identifiers for column/table names
            StringBuffer query = new StringBuffer("SELECT LOCATE(");
            query.append("?, ");
            query.append(this.blobColumnName);
            query.append(", ");
            query.append(start);
            query.append(") FROM ");
            query.append(this.tableName);
            query.append(" WHERE ");

            query.append((String) this.primaryKeyColumns.get(0));
            query.append(" = ?");

            for (int i = 1; i < this.numPrimaryKeys; i++) {
                  query.append(" AND ");
                  query.append((String) this.primaryKeyColumns.get(i));
                  query.append(" = ?");
            }

            try {
                  // FIXME: Have this passed in instead
                  pStmt = this.creatorResultSet.connection.prepareStatement(query
                              .toString());
                  pStmt.setBytes(1, pattern);

                  for (int i = 0; i < this.numPrimaryKeys; i++) {
                        pStmt.setString(i + 2, (String) this.primaryKeyValues.get(i));
                  }

                  blobRs = pStmt.executeQuery();

                  if (blobRs.next()) {
                        return blobRs.getLong(1);
                  }

                  throw SQLError.createSQLException(
                              "BLOB data not found! Did primary keys change?",
                              SQLError.SQL_STATE_GENERAL_ERROR);
            } finally {
                  if (blobRs != null) {
                        try {
                              blobRs.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        blobRs = null;
                  }

                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        pStmt = null;
                  }
            }
      }

      /**
       * @see Blob#truncate(long)
       */
00455       public void truncate(long length) throws SQLException {
            java.sql.PreparedStatement pStmt = null;

            // FIXME: Needs to use identifiers for column/table names
            StringBuffer query = new StringBuffer("UPDATE ");
            query.append(this.tableName);
            query.append(" SET ");
            query.append(this.blobColumnName);
            query.append(" = LEFT(");
            query.append(this.blobColumnName);
            query.append(", ");
            query.append(length);
            query.append(") WHERE ");

            query.append((String) this.primaryKeyColumns.get(0));
            query.append(" = ?");

            for (int i = 1; i < this.numPrimaryKeys; i++) {
                  query.append(" AND ");
                  query.append((String) this.primaryKeyColumns.get(i));
                  query.append(" = ?");
            }

            try {
                  // FIXME: Have this passed in instead
                  pStmt = this.creatorResultSet.connection.prepareStatement(query
                              .toString());

                  for (int i = 0; i < this.numPrimaryKeys; i++) {
                        pStmt.setString(i + 1, (String) this.primaryKeyValues.get(i));
                  }

                  int rowsUpdated = pStmt.executeUpdate();

                  if (rowsUpdated != 1) {
                        throw SQLError.createSQLException(
                                    "BLOB data not found! Did primary keys change?",
                                    SQLError.SQL_STATE_GENERAL_ERROR);
                  }
            } finally {
                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        pStmt = null;
                  }
            }
      }

      java.sql.PreparedStatement createGetBytesStatement() throws SQLException {
            StringBuffer query = new StringBuffer("SELECT SUBSTRING(");

            query.append(this.blobColumnName);
            query.append(", ");
            query.append("?");
            query.append(", ");
            query.append("?");
            query.append(") FROM ");
            query.append(this.tableName);
            query.append(" WHERE ");

            query.append((String) this.primaryKeyColumns.get(0));
            query.append(" = ?");

            for (int i = 1; i < this.numPrimaryKeys; i++) {
                  query.append(" AND ");
                  query.append((String) this.primaryKeyColumns.get(i));
                  query.append(" = ?");
            }

            return this.creatorResultSet.connection.prepareStatement(query
                        .toString());
      }

      byte[] getBytesInternal(java.sql.PreparedStatement pStmt, long pos,
                  int length) throws SQLException {

            java.sql.ResultSet blobRs = null;

            try {

                  pStmt.setLong(1, pos);
                  pStmt.setInt(2, length);

                  for (int i = 0; i < this.numPrimaryKeys; i++) {
                        pStmt.setString(i + 3, (String) this.primaryKeyValues.get(i));
                  }

                  blobRs = pStmt.executeQuery();

                  if (blobRs.next()) {
                        return ((com.mysql.jdbc.ResultSetImpl) blobRs).getBytes(1, true);
                  }

                  throw SQLError.createSQLException(
                              "BLOB data not found! Did primary keys change?",
                              SQLError.SQL_STATE_GENERAL_ERROR);
            } finally {
                  if (blobRs != null) {
                        try {
                              blobRs.close();
                        } catch (SQLException sqlEx) {
                              ; // do nothing
                        }

                        blobRs = null;
                  }
            }
      }

      class LocatorInputStream extends InputStream {
            long currentPositionInBlob = 0;

            long length = 0;

            java.sql.PreparedStatement pStmt = null;

            LocatorInputStream() throws SQLException {
                  length = length();
                  pStmt = createGetBytesStatement();
            }

            public int read() throws IOException {
                  if (currentPositionInBlob + 1 > length) {
                        return -1;
                  }

                  try {
                        byte[] asBytes = getBytesInternal(pStmt,
                                    (currentPositionInBlob++) + 1, 1);

                        if (asBytes == null) {
                              return -1;
                        }

                        return asBytes[0];
                  } catch (SQLException sqlEx) {
                        throw new IOException(sqlEx.toString());
                  }
            }

            /*
             * (non-Javadoc)
             * 
             * @see java.io.InputStream#read(byte[], int, int)
             */
            public int read(byte[] b, int off, int len) throws IOException {
                  if (currentPositionInBlob + 1 > length) {
                        return -1;
                  }

                  try {
                        byte[] asBytes = getBytesInternal(pStmt,
                                    (currentPositionInBlob) + 1, len);

                        if (asBytes == null) {
                              return -1;
                        }

                        System.arraycopy(asBytes, 0, b, off, asBytes.length);

                        currentPositionInBlob += asBytes.length;

                        return asBytes.length;
                  } catch (SQLException sqlEx) {
                        throw new IOException(sqlEx.toString());
                  }
            }

            /*
             * (non-Javadoc)
             * 
             * @see java.io.InputStream#read(byte[])
             */
            public int read(byte[] b) throws IOException {
                  if (currentPositionInBlob + 1 > length) {
                        return -1;
                  }

                  try {
                        byte[] asBytes = getBytesInternal(pStmt,
                                    (currentPositionInBlob) + 1, b.length);

                        if (asBytes == null) {
                              return -1;
                        }

                        System.arraycopy(asBytes, 0, b, 0, asBytes.length);

                        currentPositionInBlob += asBytes.length;

                        return asBytes.length;
                  } catch (SQLException sqlEx) {
                        throw new IOException(sqlEx.toString());
                  }
            }

            /*
             * (non-Javadoc)
             * 
             * @see java.io.InputStream#close()
             */
            public void close() throws IOException {
                  if (pStmt != null) {
                        try {
                              pStmt.close();
                        } catch (SQLException sqlEx) {
                              throw new IOException(sqlEx.toString());
                        }
                  }

                  super.close();
            }
      }

      public void free() throws SQLException {
            this.creatorResultSet = null;
            this.primaryKeyColumns = null;
            this.primaryKeyValues = null;
      }

      public InputStream getBinaryStream(long pos, long length) throws SQLException {
            throw new NotYetImplementedException();
      }
}

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