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.cloudata.examples.web; import java.io.IOException; import java.util.Collection; import java.util.Date; import java.util.Iterator; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Writable; import org.apache.hadoop.io.WritableComparable; import org.apache.hadoop.mapred.FileOutputFormat; import org.apache.hadoop.mapred.JobClient; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapred.Mapper; import org.apache.hadoop.mapred.OutputCollector; import org.apache.hadoop.mapred.Reducer; import org.apache.hadoop.mapred.Reporter; import org.cloudata.core.client.Cell; import org.cloudata.core.client.CTable; import org.cloudata.core.client.Row; import org.cloudata.core.common.conf.CloudataConf; import org.cloudata.core.parallel.hadoop.DefaultTabletInputFormat; import org.cloudata.core.tablet.TableSchema; public class TermGlobalJob { public static final Log LOG = LogFactory.getLog(TermGlobalJob.class.getName()); public static final String GLOBAL_TABLE = "T_GLOBAL"; public static final String[] GLOBAL_TABLE_COLUMNS = new String[] { "doclengh", "doccount" }; public static final Row.Key GLOBAL_TABLE_ROWKEY = new Row.Key("WebGlobalVariable"); public void exec() throws Exception { CloudataConf nconf = new CloudataConf(); if (!CTable.existsTable(nconf, GLOBAL_TABLE)) { TableSchema globalTableInfo = new TableSchema(GLOBAL_TABLE, "Test", GLOBAL_TABLE_COLUMNS); CTable.createTable(nconf, globalTableInfo); } Path tempOutputPath = new Path("globalTableInfo" + System.currentTimeMillis()); JobConf jobConf = new JobConf(WebTableJob.class); jobConf.setJobName("TermGlobalJob" + "(" + new Date() + ")"); //<MAP> jobConf.setMapperClass(TermGlobalMap.class); jobConf.setInputFormat(DefaultTabletInputFormat.class); jobConf.set(DefaultTabletInputFormat.INPUT_TABLE, WebTableJob.WEB_TABLE); jobConf.set(DefaultTabletInputFormat.INPUT_COLUMN_LIST, WebTableJob.WEB_TABLE_COLUMNS[2]); jobConf.setMapOutputKeyClass(Text.class); jobConf.setMapOutputValueClass(Text.class); //</MAP> //<REDUCE> jobConf.setReducerClass(TermGlobalReduce.class); jobConf.setOutputKeyClass(Text.class); jobConf.setOutputValueClass(Text.class); jobConf.setNumReduceTasks(1); jobConf.setMaxReduceAttempts(0); FileOutputFormat.setOutputPath(jobConf, tempOutputPath); //</REDUCE> //Run Job JobClient.runJob(jobConf); //delete temp output path FileSystem fs = FileSystem.get(jobConf); fs.delete(tempOutputPath, true); } static class TermGlobalMap implements Mapper<Row.Key, Row, WritableComparable, Writable> { static final Log LOG = LogFactory.getLog(TermGlobalMap.class.getName()); long sumDocLength; long sumDocCount; OutputCollector<WritableComparable, Writable> collector; public void map(Row.Key key, Row value, OutputCollector<WritableComparable, Writable> collector, Reporter reporter) throws IOException { if (this.collector == null) { this.collector = collector; } String document = new String(key.getBytes(), 0, key.getLength(), "EUC-KR"); if (value.getColumnSize() < 1) { LOG.warn("Length of RowColumnValuesArray less than 1: " + document); return; } Collection<Cell> cells = value.getFirstColumnCells(); if (cells == null) { LOG.warn("Contents column is empty : " + document); return; } //contents? term ? term, document, freq write. byte[] contentsBytes = cells.iterator().next().getBytes(); if (contentsBytes == null || contentsBytes.length == 0) { LOG.info("Contents is null: " + document); return; } sumDocLength += contentsBytes.length; sumDocCount++; } public void configure(JobConf jobConf) { } public void close() throws IOException { LOG.info("sumDocLength: " + sumDocLength + ",sumDocCount: " + sumDocCount); collector.collect(new Text(String.valueOf(System.currentTimeMillis())), new Text(Long.toString(sumDocLength) + "\t" + Long.toString(sumDocCount))); } } static class TermGlobalReduce implements Reducer<WritableComparable, Writable, WritableComparable, Writable> { static final Log LOG = LogFactory.getLog(TermGlobalReduce.class.getName()); long sumDocLength; long sumDocCount; public void reduce(WritableComparable key, Iterator<Writable> values, OutputCollector<WritableComparable, Writable> collector, Reporter reporter) throws IOException { while (values.hasNext()) { String[] tokens = values.next().toString().split("\t"); sumDocLength += Long.parseLong(tokens[0]); sumDocCount += Long.parseLong(tokens[1]); } } public void configure(JobConf jobConf) { } public void close() throws IOException { CTable table = CTable.openTable(new CloudataConf(), GLOBAL_TABLE); try { Row row = new Row(GLOBAL_TABLE_ROWKEY); row.addCell("doclengh", new Cell(Cell.Key.EMPTY_KEY, Long.toString(sumDocLength).getBytes())); row.addCell("doccount", new Cell(Cell.Key.EMPTY_KEY, Long.toString(sumDocCount).getBytes())); table.put(row); } catch (IOException e) { LOG.error(e); } } } }