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.warcbase.mapreduce.lib; import java.io.IOException; import java.net.URI; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configuration.IntegerRanges; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.RawComparator; import org.apache.hadoop.mapreduce.Counter; import org.apache.hadoop.mapreduce.InputFormat; import org.apache.hadoop.mapreduce.InputSplit; import org.apache.hadoop.mapreduce.JobID; import org.apache.hadoop.mapreduce.MapContext; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.OutputCommitter; import org.apache.hadoop.mapreduce.OutputFormat; import org.apache.hadoop.mapreduce.Partitioner; import org.apache.hadoop.mapreduce.RecordReader; import org.apache.hadoop.mapreduce.RecordWriter; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.TaskAttemptID; import org.apache.hadoop.mapreduce.TaskInputOutputContext; import org.apache.hadoop.security.Credentials; /** * A simple wrapper class that delegates most of its functionality to the * underlying context, but overrides the methods to do with record readers , * record writers and configuration. */ class ChainMapContextImpl<KEYIN, VALUEIN, KEYOUT, VALUEOUT> implements MapContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> { private RecordReader<KEYIN, VALUEIN> reader; private RecordWriter<KEYOUT, VALUEOUT> output; private TaskInputOutputContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> base; private Configuration conf; ChainMapContextImpl(TaskInputOutputContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> base, RecordReader<KEYIN, VALUEIN> rr, RecordWriter<KEYOUT, VALUEOUT> rw, Configuration conf) { this.reader = rr; this.output = rw; this.base = base; this.conf = conf; } @Override public KEYIN getCurrentKey() throws IOException, InterruptedException { return reader.getCurrentKey(); } @Override public VALUEIN getCurrentValue() throws IOException, InterruptedException { return reader.getCurrentValue(); } @Override public boolean nextKeyValue() throws IOException, InterruptedException { return reader.nextKeyValue(); } @Override public InputSplit getInputSplit() { if (base instanceof MapContext) { MapContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> mc = (MapContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT>) base; return mc.getInputSplit(); } else { return null; } } @Override public Counter getCounter(Enum<?> counterName) { return base.getCounter(counterName); } @Override public Counter getCounter(String groupName, String counterName) { return base.getCounter(groupName, counterName); } @Override public OutputCommitter getOutputCommitter() { return base.getOutputCommitter(); } @Override public void write(KEYOUT key, VALUEOUT value) throws IOException, InterruptedException { output.write(key, value); } @Override public String getStatus() { return base.getStatus(); } @Override public TaskAttemptID getTaskAttemptID() { return base.getTaskAttemptID(); } @Override public void setStatus(String msg) { base.setStatus(msg); } @Override public Path[] getArchiveClassPaths() { return base.getArchiveClassPaths(); } @Override public String[] getArchiveTimestamps() { return base.getArchiveTimestamps(); } @Override public URI[] getCacheArchives() throws IOException { return base.getCacheArchives(); } @Override public URI[] getCacheFiles() throws IOException { return base.getCacheFiles(); } @Override public Class<? extends Reducer<?, ?, ?, ?>> getCombinerClass() throws ClassNotFoundException { return base.getCombinerClass(); } @Override public Configuration getConfiguration() { return conf; } @Override public Path[] getFileClassPaths() { return base.getFileClassPaths(); } @Override public String[] getFileTimestamps() { return base.getFileTimestamps(); } @Override public RawComparator<?> getCombinerKeyGroupingComparator() { return base.getCombinerKeyGroupingComparator(); } @Override public RawComparator<?> getGroupingComparator() { return base.getGroupingComparator(); } @Override public Class<? extends InputFormat<?, ?>> getInputFormatClass() throws ClassNotFoundException { return base.getInputFormatClass(); } @Override public String getJar() { return base.getJar(); } @Override public JobID getJobID() { return base.getJobID(); } @Override public String getJobName() { return base.getJobName(); } @Override public boolean userClassesTakesPrecedence() { return base.userClassesTakesPrecedence(); } @Override public boolean getJobSetupCleanupNeeded() { return base.getJobSetupCleanupNeeded(); } @Override public boolean getTaskCleanupNeeded() { return base.getTaskCleanupNeeded(); } @Override public Path[] getLocalCacheArchives() throws IOException { return base.getLocalCacheArchives(); } @Override public Path[] getLocalCacheFiles() throws IOException { return base.getLocalCacheArchives(); } @Override public Class<?> getMapOutputKeyClass() { return base.getMapOutputKeyClass(); } @Override public Class<?> getMapOutputValueClass() { return base.getMapOutputValueClass(); } @Override public Class<? extends Mapper<?, ?, ?, ?>> getMapperClass() throws ClassNotFoundException { return base.getMapperClass(); } @Override public int getMaxMapAttempts() { return base.getMaxMapAttempts(); } @Override public int getMaxReduceAttempts() { return base.getMaxReduceAttempts(); } @Override public int getNumReduceTasks() { return base.getNumReduceTasks(); } @Override public Class<? extends OutputFormat<?, ?>> getOutputFormatClass() throws ClassNotFoundException { return base.getOutputFormatClass(); } @Override public Class<?> getOutputKeyClass() { return base.getMapOutputKeyClass(); } @Override public Class<?> getOutputValueClass() { return base.getOutputValueClass(); } @Override public Class<? extends Partitioner<?, ?>> getPartitionerClass() throws ClassNotFoundException { return base.getPartitionerClass(); } @Override public boolean getProfileEnabled() { return base.getProfileEnabled(); } @Override public String getProfileParams() { return base.getProfileParams(); } @Override public IntegerRanges getProfileTaskRange(boolean isMap) { return base.getProfileTaskRange(isMap); } @Override public Class<? extends Reducer<?, ?, ?, ?>> getReducerClass() throws ClassNotFoundException { return base.getReducerClass(); } @Override public RawComparator<?> getSortComparator() { return base.getSortComparator(); } @Override public boolean getSymlink() { return base.getSymlink(); } @Override public String getUser() { return base.getUser(); } @Override public Path getWorkingDirectory() throws IOException { return base.getWorkingDirectory(); } @Override public void progress() { base.progress(); } @Override public Credentials getCredentials() { return base.getCredentials(); } @Override public float getProgress() { return base.getProgress(); } }