Java tutorial
/** * 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 org.apache.hadoop.mapreduce.lib.db; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.lib.db.DBInputFormat.NullDBWritable; /** * A container for configuration property names for jobs with DB input/output. * * The job can be configured using the static methods in this class, * {@link DBInputFormat}, and {@link DBOutputFormat}. * Alternatively, the properties can be set in the configuration with proper * values. * * @see DBConfiguration#configureDB(Configuration, String, String, String, String) * @see DBInputFormat#setInput(Job, Class, String, String) * @see DBInputFormat#setInput(Job, Class, String, String, String, String...) * @see DBOutputFormat#setOutput(Job, String, String...) */ @InterfaceAudience.Public @InterfaceStability.Stable public class DBConfiguration { /** The JDBC Driver class name */ public static final String DRIVER_CLASS_PROPERTY = "mapreduce.jdbc.driver.class"; /** JDBC Database access URL */ public static final String URL_PROPERTY = "mapreduce.jdbc.url"; /** User name to access the database */ public static final String USERNAME_PROPERTY = "mapreduce.jdbc.username"; /** Password to access the database */ public static final String PASSWORD_PROPERTY = "mapreduce.jdbc.password"; /** Input table name */ public static final String INPUT_TABLE_NAME_PROPERTY = "mapreduce.jdbc.input.table.name"; /** Field names in the Input table */ public static final String INPUT_FIELD_NAMES_PROPERTY = "mapreduce.jdbc.input.field.names"; /** WHERE clause in the input SELECT statement */ public static final String INPUT_CONDITIONS_PROPERTY = "mapreduce.jdbc.input.conditions"; /** ORDER BY clause in the input SELECT statement */ public static final String INPUT_ORDER_BY_PROPERTY = "mapreduce.jdbc.input.orderby"; /** Whole input query, exluding LIMIT...OFFSET */ public static final String INPUT_QUERY = "mapreduce.jdbc.input.query"; /** Input query to get the count of records */ public static final String INPUT_COUNT_QUERY = "mapreduce.jdbc.input.count.query"; /** Input query to get the max and min values of the jdbc.input.query */ public static final String INPUT_BOUNDING_QUERY = "mapred.jdbc.input.bounding.query"; /** Class name implementing DBWritable which will hold input tuples */ public static final String INPUT_CLASS_PROPERTY = "mapreduce.jdbc.input.class"; /** Output table name */ public static final String OUTPUT_TABLE_NAME_PROPERTY = "mapreduce.jdbc.output.table.name"; /** Field names in the Output table */ public static final String OUTPUT_FIELD_NAMES_PROPERTY = "mapreduce.jdbc.output.field.names"; /** Number of fields in the Output table */ public static final String OUTPUT_FIELD_COUNT_PROPERTY = "mapreduce.jdbc.output.field.count"; /** * Sets the DB access related fields in the {@link Configuration}. * @param conf the configuration * @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(Configuration conf, String driverClass, String dbUrl, String userName, String passwd) { conf.set(DRIVER_CLASS_PROPERTY, driverClass); conf.set(URL_PROPERTY, dbUrl); if (userName != null) { conf.set(USERNAME_PROPERTY, userName); } if (passwd != null) { conf.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(Configuration job, String driverClass, String dbUrl) { configureDB(job, driverClass, dbUrl, null, null); } private Configuration conf; public DBConfiguration(Configuration job) { this.conf = job; } /** Returns a connection object o the DB * @throws ClassNotFoundException * @throws SQLException */ public Connection getConnection() throws ClassNotFoundException, SQLException { Class.forName(conf.get(DBConfiguration.DRIVER_CLASS_PROPERTY)); if (conf.get(DBConfiguration.USERNAME_PROPERTY) == null) { return DriverManager.getConnection(conf.get(DBConfiguration.URL_PROPERTY)); } else { return DriverManager.getConnection(conf.get(DBConfiguration.URL_PROPERTY), conf.get(DBConfiguration.USERNAME_PROPERTY), conf.get(DBConfiguration.PASSWORD_PROPERTY)); } } public Configuration getConf() { return conf; } public String getInputTableName() { return conf.get(DBConfiguration.INPUT_TABLE_NAME_PROPERTY); } public void setInputTableName(String tableName) { conf.set(DBConfiguration.INPUT_TABLE_NAME_PROPERTY, tableName); } public String[] getInputFieldNames() { return conf.getStrings(DBConfiguration.INPUT_FIELD_NAMES_PROPERTY); } public void setInputFieldNames(String... fieldNames) { conf.setStrings(DBConfiguration.INPUT_FIELD_NAMES_PROPERTY, fieldNames); } public String getInputConditions() { return conf.get(DBConfiguration.INPUT_CONDITIONS_PROPERTY); } public void setInputConditions(String conditions) { if (conditions != null && conditions.length() > 0) conf.set(DBConfiguration.INPUT_CONDITIONS_PROPERTY, conditions); } public String getInputOrderBy() { return conf.get(DBConfiguration.INPUT_ORDER_BY_PROPERTY); } public void setInputOrderBy(String orderby) { if (orderby != null && orderby.length() > 0) { conf.set(DBConfiguration.INPUT_ORDER_BY_PROPERTY, orderby); } } public String getInputQuery() { return conf.get(DBConfiguration.INPUT_QUERY); } public void setInputQuery(String query) { if (query != null && query.length() > 0) { conf.set(DBConfiguration.INPUT_QUERY, query); } } public String getInputCountQuery() { return conf.get(DBConfiguration.INPUT_COUNT_QUERY); } public void setInputCountQuery(String query) { if (query != null && query.length() > 0) { conf.set(DBConfiguration.INPUT_COUNT_QUERY, query); } } public void setInputBoundingQuery(String query) { if (query != null && query.length() > 0) { conf.set(DBConfiguration.INPUT_BOUNDING_QUERY, query); } } public String getInputBoundingQuery() { return conf.get(DBConfiguration.INPUT_BOUNDING_QUERY); } public Class<?> getInputClass() { return conf.getClass(DBConfiguration.INPUT_CLASS_PROPERTY, NullDBWritable.class); } public void setInputClass(Class<? extends DBWritable> inputClass) { conf.setClass(DBConfiguration.INPUT_CLASS_PROPERTY, inputClass, DBWritable.class); } public String getOutputTableName() { return conf.get(DBConfiguration.OUTPUT_TABLE_NAME_PROPERTY); } public void setOutputTableName(String tableName) { conf.set(DBConfiguration.OUTPUT_TABLE_NAME_PROPERTY, tableName); } public String[] getOutputFieldNames() { return conf.getStrings(DBConfiguration.OUTPUT_FIELD_NAMES_PROPERTY); } public void setOutputFieldNames(String... fieldNames) { conf.setStrings(DBConfiguration.OUTPUT_FIELD_NAMES_PROPERTY, fieldNames); } public void setOutputFieldCount(int fieldCount) { conf.setInt(DBConfiguration.OUTPUT_FIELD_COUNT_PROPERTY, fieldCount); } public int getOutputFieldCount() { return conf.getInt(OUTPUT_FIELD_COUNT_PROPERTY, 0); } }