com.cloudera.crunch.type.writable.TextMapWritable.java Source code

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Here is the source code for com.cloudera.crunch.type.writable.TextMapWritable.java

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/**
 * Copyright (c) 2011, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.crunch.type.writable;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Map;
import java.util.Set;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;

import com.google.common.collect.Maps;

public class TextMapWritable<T extends Writable> implements Writable {

    private Class<T> valueClazz;
    private final Map<Text, T> instance;

    public TextMapWritable() {
        this.instance = Maps.newHashMap();
    }

    public TextMapWritable(Class<T> valueClazz) {
        this.valueClazz = valueClazz;
        this.instance = Maps.newHashMap();
    }

    public void put(Text txt, T value) {
        instance.put(txt, value);
    }

    public Set<Map.Entry<Text, T>> entrySet() {
        return instance.entrySet();
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        instance.clear();
        try {
            this.valueClazz = (Class<T>) Class.forName(Text.readString(in));
        } catch (ClassNotFoundException e) {
            throw (IOException) new IOException("Failed map init").initCause(e);
        }
        int entries = WritableUtils.readVInt(in);
        try {
            for (int i = 0; i < entries; i++) {
                Text txt = new Text();
                txt.readFields(in);
                T value = valueClazz.newInstance();
                value.readFields(in);
                instance.put(txt, value);
            }
        } catch (IllegalAccessException e) {
            throw (IOException) new IOException("Failed map init").initCause(e);
        } catch (InstantiationException e) {
            throw (IOException) new IOException("Failed map init").initCause(e);
        }
    }

    @Override
    public void write(DataOutput out) throws IOException {
        Text.writeString(out, valueClazz.getName());
        WritableUtils.writeVInt(out, instance.size());
        for (Map.Entry<Text, T> e : instance.entrySet()) {
            e.getKey().write(out);
            e.getValue().write(out);
        }
    }

}