Java tutorial
/** * Starschema Big Query JDBC Driver * Copyright (C) 2012, Starschema Ltd. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * any later version. * * 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, see <http://www.gnu.org/licenses/>. * * This class implements the java.sql.ResultSetMetaData interface */ package net.starschema.clouddb.jdbc; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Timestamp; import java.util.List; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.google.api.client.util.Data; import com.google.api.services.bigquery.model.GetQueryResultsResponse; import com.google.api.services.bigquery.model.TableFieldSchema; import com.google.api.services.bigquery.model.TableSchema; // import net.starschema.clouddb.bqjdbc.logging.Logger; /** * This class implements the java.sql.ResultSetMetadata interface * * @author Horvth Attila * */ class BQResultsetMetaData implements ResultSetMetaData { /** Reference of the bigquery GetQueryResultsResponse object */ GetQueryResultsResponse result = null; /** Reference of the bigquery GetQueryResultsResponse object */ ResultSet results = null; /** Logger instance */ private final Log logger = LogFactory.getLog(getClass()); /** * Constructor that initializes variables * * @param result * the bigquery GetQueryResultsResponse object */ public BQResultsetMetaData(GetQueryResultsResponse result) { //logger.debug("function call getResultSetMetaData()"); this.result = result; } /** * <p> * <h1>Implementation Details:</h1><br> * Returns the BigQuery Projects ID * </p> * * @return projectID */ @Override public String getCatalogName(int column) throws SQLException { logger.debug("function call getCatalogName() return is: " + this.result.getJobReference().getProjectId()); return this.result.getJobReference().getProjectId(); } /** * <p> * <h1>Implementation Details:</h1><br> * Not implemented yet. * </p> * * @throws BQSQLException */ @Override public String getColumnClassName(int column) throws SQLException { this.logger.debug("Function call getcolumnclassname(" + column + ")"); String Columntype = null; try { Columntype = this.result.getSchema().getFields().get(column - 1).getType(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException(e); } catch (NullPointerException e) { throw new BQSQLException(e); } if (Columntype.equals("FLOAT")) { return Double.class.getName(); } if (Columntype.equals("BOOLEAN")) { return Boolean.class.getName(); } if (Columntype.equals("INTEGER")) { return Long.class.getName(); } if (Columntype.equals("STRING")) { return String.class.getName(); } if (Columntype.equals("TIMESTAMP")) { return Timestamp.class.getName(); } throw new BQSQLException("Unsupported Type: " + Columntype); } /** {@inheritDoc} */ @Override public int getColumnCount() throws SQLException { TableSchema schema = this.result.getSchema(); List<TableFieldSchema> schemafieldlist = null; if (schema != null) { schemafieldlist = schema.getFields(); } else { return 0; } if (schemafieldlist != null) { return this.result.getSchema().getFields().size(); } else { return 0; } } /** * <p> * <h1>Implementation Details:</h1><br> * returns 64*1024 * </p> * */ @Override public int getColumnDisplaySize(int column) throws SQLException { return 1024 * 64; // TODO Check the maximum lenght of characters contained in this // resulset for each column } /** {@inheritDoc} */ @Override public String getColumnLabel(int column) throws SQLException { if (this.getColumnCount() == 0) { throw new IndexOutOfBoundsException(); } try { return this.result.getSchema().getFields().get(column - 1).getName(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException(e); } } /** {@inheritDoc} */ @Override public String getColumnName(int column) throws SQLException { if (this.getColumnCount() == 0) { throw new BQSQLException("getColumnName(int)", new IndexOutOfBoundsException()); } try { return this.result.getSchema().getFields().get(column - 1).getName(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException("getColumnName(int)", e); } } /** * {@inheritDoc} <br> * note: This Can only Return due to bigquery:<br> * java.sql.Types.DOUBLE<br> * java.sql.Types.BOOLEAN<br> * java.sql.Types.BIGINT<br> * java.sql.Types.VARCHAR<br> * java.sql.Types.TIMESTAMP<br> * */ @Override public int getColumnType(int column) throws SQLException { if (this.getColumnCount() == 0) { return 0; } String Columntype = ""; try { Columntype = this.result.getSchema().getFields().get(column - 1).getType(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException("getColumnType(int)", e); } if (Columntype.equals("FLOAT")) { return java.sql.Types.DOUBLE; // Float in BigQuery maps to the DOUBLE sql type } if (Columntype.equals("BOOLEAN")) { return java.sql.Types.BOOLEAN; } if (Columntype.equals("INTEGER")) { return java.sql.Types.BIGINT; // INTEGER in BigQuery has 64 bits so it maps BIGINT sql type (Sql INTEGER is "only" 32 bits) } if (Columntype.equals("STRING")) { return java.sql.Types.VARCHAR; } if (Columntype.equals("TIMESTAMP")) { return java.sql.Types.TIMESTAMP; } throw new BQSQLException("Unsupported Type: " + Columntype); // May arise if a new data type is added to BigQuery. A new release of the driver would then be needed in order to map it correctly } /** {@inheritDoc} */ @Override public String getColumnTypeName(int column) throws SQLException { if (this.getColumnCount() == 0) { throw new BQSQLException("getcolumnTypeName(int)", new IndexOutOfBoundsException()); } String Columntype = ""; try { Columntype = this.result.getSchema().getFields().get(column - 1).getType(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException("getColumnTypeName(int)", e); } return Columntype; } /** {@inheritDoc} */ @Override public int getPrecision(int column) throws SQLException { if (this.getColumnCount() == 0) { return 0; } String Columntype = ""; try { Columntype = this.result.getSchema().getFields().get(column - 1).getType(); } catch (IndexOutOfBoundsException e) { throw new BQSQLException("getPrecision(int)", e); } if (Columntype.equals("FLOAT")) { return Float.MAX_EXPONENT; } if (Columntype.equals("BOOLEAN")) { return 1; // A boolean is 1 bit length, but it asks for byte, so // 1 } if (Columntype.equals("INTEGER")) { return 64; // BigQuery's Integer have 64 bits } if (Columntype.equals("STRING")) { return 64 * 1024; } if (Columntype.equals("TIMESTAMP")) { return 50; // TODO: better computation of the maximum length of a string representation of the date } return 0; } /** * <p> * <h1>Implementation Details:</h1><br> * Not implemented yet. * </p> * * @throws BQSQLException */ @Override public int getScale(int column) throws SQLException { if (this.getColumnType(column) == java.sql.Types.DOUBLE) { int max = 0; for (int i = 0; i < this.result.getRows().size(); i++) { Object rowdataObject = this.result.getRows().get(i).getF().get(column - 1).getV(); if (Data.isNull(rowdataObject)) { return 0; } String rowdata = (String) rowdataObject; if (rowdata.contains(".")) { int pointback = rowdata.length() - rowdata.indexOf("."); if (pointback > max) { pointback = max; } } } return max; } else { return 0; } } /** * <p> * <h1>Implementation Details:</h1><br> * No support in bigquery to get the schema for the column. * </p> * * @return "" */ @Override public String getSchemaName(int column) throws SQLException { logger.debug("Function call getSchemaName(" + column + ") will return empty string "); return ""; } /** * <p> * <h1>Implementation Details:</h1><br> * No option in BigQuery api to get the Table name from column. * </p> * * @return "" */ @Override public String getTableName(int column) throws SQLException { logger.debug("Function call getTableName(" + column + ") will return empty string "); return ""; } /** * <p> * <h1>Implementation Details:</h1><br> * No ato increment option in bigquery. * </p> * * @return false */ @Override public boolean isAutoIncrement(int column) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns false * </p> * * @return false */ @Override public boolean isCaseSensitive(int column) throws SQLException { //FIXME really? // Google bigquery is case insensitive return false; } /** * <p> * <h1>Implementation Details:</h1><br> * We store everything as string. * </p> * * @return false */ @Override public boolean isCurrency(int column) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns false * </p> * * @return false */ @Override public boolean isDefinitelyWritable(int column) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns ResultSetMetaData.columnNullable * </p> * * @return ResultSetMetaData.columnNullable */ @Override public int isNullable(int column) throws SQLException { return ResultSetMetaData.columnNullable; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns true * </p> * * @return true */ @Override public boolean isReadOnly(int column) throws SQLException { return true; } /** * <p> * <h1>Implementation Details:</h1><br> * Everything can be in Where. * </p> * * @return true */ @Override public boolean isSearchable(int column) throws SQLException { return true; } /** * <p> * <h1>Implementation Details:</h1><br> * Partly implemented. * </p> * * @return false; */ @Override public boolean isSigned(int column) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns false * </p> * * @return false */ @Override public boolean isWrapperFor(Class<?> iface) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always returns false * </p> * * @return false */ @Override public boolean isWritable(int column) throws SQLException { return false; } /** * <p> * <h1>Implementation Details:</h1><br> * Always throws SQLExceptionL * </p> * * @throws SQLException * always */ @Override public <T> T unwrap(Class<T> iface) throws SQLException { throw new BQSQLException("Not found"); } }