Java tutorial
/* * Copyright (c) 2009 Concurrent, Inc. * * This work has been released into the public domain * by the copyright holder. This applies worldwide. * * In case this is not legally possible: * The copyright holder grants any entity the right * to use this work for any purpose, without any * conditions, unless such conditions are required by law. */ /** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package cascading.jdbc.db; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import org.apache.hadoop.mapred.JobConf; /** * A container for configuration property names for jobs with DB input/output. * <br> * The job can be configured using the static methods in this class, * {@link DBInputFormat}, and {@link DBOutputFormat}. * <p/> * Alternatively, the properties can be set in the configuration with proper * values. */ public class DBConfiguration { /** The JDBC Driver class name */ public static final String DRIVER_CLASS_PROPERTY = "mapred.jdbc.driver.class"; /** JDBC Database access URL */ public static final String URL_PROPERTY = "mapred.jdbc.url"; /** User name to access the database */ public static final String USERNAME_PROPERTY = "mapred.jdbc.username"; /** Password to access the database */ public static final String PASSWORD_PROPERTY = "mapred.jdbc.password"; /** Input table name */ public static final String INPUT_TABLE_NAME_PROPERTY = "mapred.jdbc.input.table.name"; /** Field names in the Input table */ public static final String INPUT_FIELD_NAMES_PROPERTY = "mapred.jdbc.input.field.names"; /** WHERE clause in the input SELECT statement */ public static final String INPUT_CONDITIONS_PROPERTY = "mapred.jdbc.input.conditions"; /** ORDER BY clause in the input SELECT statement */ public static final String INPUT_ORDER_BY_PROPERTY = "mapred.jdbc.input.orderby"; /** Whole input query, exluding LIMIT...OFFSET */ public static final String INPUT_QUERY = "mapred.jdbc.input.query"; /** The number of records to LIMIT, useful for testing */ public static final String INPUT_LIMIT = "mapred.jdbc.input.limit"; /** Input query to get the count of records */ public static final String INPUT_COUNT_QUERY = "mapred.jdbc.input.count.query"; /** Class name implementing DBWritable which will hold input tuples */ public static final String INPUT_CLASS_PROPERTY = "mapred.jdbc.input.class"; /** Output table name */ public static final String OUTPUT_TABLE_NAME_PROPERTY = "mapred.jdbc.output.table.name"; /** Field names in the Output table */ public static final String OUTPUT_FIELD_NAMES_PROPERTY = "mapred.jdbc.output.field.names"; /** Field names in the Output table */ public static final String OUTPUT_UPDATE_FIELD_NAMES_PROPERTY = "mapred.jdbc.output.update.field.names"; /** The number of statements to batch before executing */ public static final String BATCH_STATEMENTS_PROPERTY = "mapred.jdbc.batch.statements.num"; /** The number of splits allowed, becomes max concurrent reads. */ public static final String CONCURRENT_READS_PROPERTY = "mapred.jdbc.concurrent.reads.num"; /** * Sets the DB access related fields in the JobConf. * * @param job the job * @param driverClass JDBC Driver class name * @param dbUrl JDBC DB access URL. * @param userName DB access username * @param passwd DB access passwd */ public static void configureDB(JobConf job, String driverClass, String dbUrl, String userName, String passwd) { job.set(DRIVER_CLASS_PROPERTY, driverClass); job.set(URL_PROPERTY, dbUrl); if (userName != null) job.set(USERNAME_PROPERTY, userName); if (passwd != null) job.set(PASSWORD_PROPERTY, passwd); } /** * Sets the DB access related fields in the JobConf. * * @param job the job * @param driverClass JDBC Driver class name * @param dbUrl JDBC DB access URL. */ public static void configureDB(JobConf job, String driverClass, String dbUrl) { configureDB(job, driverClass, dbUrl, null, null); } private JobConf job; DBConfiguration(JobConf job) { this.job = job; } /** * Returns a connection object o the DB * * @throws ClassNotFoundException * @throws SQLException */ Connection getConnection() throws IOException { try { Class.forName(job.get(DBConfiguration.DRIVER_CLASS_PROPERTY)); } catch (ClassNotFoundException exception) { throw new IOException("unable to load conection driver", exception); } try { if (job.get(DBConfiguration.USERNAME_PROPERTY) == null) return DriverManager.getConnection(job.get(DBConfiguration.URL_PROPERTY)); else return DriverManager.getConnection(job.get(DBConfiguration.URL_PROPERTY), job.get(DBConfiguration.USERNAME_PROPERTY), job.get(DBConfiguration.PASSWORD_PROPERTY)); } catch (SQLException exception) { throw new IOException("unable to create connection", exception); } } String getInputTableName() { return job.get(DBConfiguration.INPUT_TABLE_NAME_PROPERTY); } void setInputTableName(String tableName) { job.set(DBConfiguration.INPUT_TABLE_NAME_PROPERTY, tableName); } String[] getInputFieldNames() { return job.getStrings(DBConfiguration.INPUT_FIELD_NAMES_PROPERTY); } void setInputFieldNames(String... fieldNames) { job.setStrings(DBConfiguration.INPUT_FIELD_NAMES_PROPERTY, fieldNames); } String getInputConditions() { return job.get(DBConfiguration.INPUT_CONDITIONS_PROPERTY); } void setInputConditions(String conditions) { if (conditions != null && conditions.length() > 0) job.set(DBConfiguration.INPUT_CONDITIONS_PROPERTY, conditions); } String getInputOrderBy() { return job.get(DBConfiguration.INPUT_ORDER_BY_PROPERTY); } void setInputOrderBy(String orderby) { if (orderby != null && orderby.length() > 0) job.set(DBConfiguration.INPUT_ORDER_BY_PROPERTY, orderby); } String getInputQuery() { return job.get(DBConfiguration.INPUT_QUERY); } void setInputQuery(String query) { if (query != null && query.length() > 0) job.set(DBConfiguration.INPUT_QUERY, query); } long getInputLimit() { return job.getLong(DBConfiguration.INPUT_LIMIT, -1); } void setInputLimit(long limit) { job.setLong(DBConfiguration.INPUT_LIMIT, limit); } String getInputCountQuery() { return job.get(DBConfiguration.INPUT_COUNT_QUERY); } void setInputCountQuery(String query) { if (query != null && query.length() > 0) job.set(DBConfiguration.INPUT_COUNT_QUERY, query); } Class<?> getInputClass() { return job.getClass(DBConfiguration.INPUT_CLASS_PROPERTY, DBInputFormat.NullDBWritable.class); } void setInputClass(Class<? extends DBWritable> inputClass) { job.setClass(DBConfiguration.INPUT_CLASS_PROPERTY, inputClass, DBWritable.class); } String getOutputTableName() { return job.get(DBConfiguration.OUTPUT_TABLE_NAME_PROPERTY); } void setOutputTableName(String tableName) { job.set(DBConfiguration.OUTPUT_TABLE_NAME_PROPERTY, tableName); } String[] getOutputFieldNames() { return job.getStrings(DBConfiguration.OUTPUT_FIELD_NAMES_PROPERTY); } void setOutputFieldNames(String... fieldNames) { job.setStrings(DBConfiguration.OUTPUT_FIELD_NAMES_PROPERTY, fieldNames); } String[] getOutputUpdateFieldNames() { return job.getStrings(DBConfiguration.OUTPUT_UPDATE_FIELD_NAMES_PROPERTY); } void setOutputUpdateFieldNames(String... fieldNames) { job.setStrings(DBConfiguration.OUTPUT_UPDATE_FIELD_NAMES_PROPERTY, fieldNames); } int getBatchStatementsNum() { return job.getInt(DBConfiguration.BATCH_STATEMENTS_PROPERTY, 1000); } void setBatchStatementsNum(int batchStatementsNum) { job.setInt(DBConfiguration.BATCH_STATEMENTS_PROPERTY, batchStatementsNum); } int getMaxConcurrentReadsNum() { return job.getInt(DBConfiguration.CONCURRENT_READS_PROPERTY, 0); } void setMaxConcurrentReadsNum(int maxConcurrentReads) { if (maxConcurrentReads < 0) throw new IllegalArgumentException("maxConcurrentReads must be a positive value"); job.setInt(DBConfiguration.CONCURRENT_READS_PROPERTY, maxConcurrentReads); } }