com.cloudera.exhibit.hive.ReadFileUDF.java Source code

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Here is the source code for com.cloudera.exhibit.hive.ReadFileUDF.java

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/*
 * Copyright (c) 2015, 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.exhibit.hive;

import com.google.common.base.Charsets;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.Lists;
import com.google.common.io.Files;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;

import java.io.File;
import java.io.IOException;
import java.util.List;

public class ReadFileUDF extends GenericUDF {

    private List<String> contents;

    private static List<String> read(String fileName, String delim) throws IOException {
        List<String> contents = Files.readLines(new File(fileName), Charsets.UTF_8);
        if (!"\n".equals(delim)) {
            contents = Lists.newArrayList(Splitter.on(delim).split(Joiner.on("\n").join(contents)));
        }
        return contents;
    }

    @Override
    public ObjectInspector initialize(ObjectInspector[] args) throws UDFArgumentException {
        if (args.length < 1 || args.length > 2) {
            throw new UDFArgumentLengthException("The read_file UDF takes at least 1 and no more than 2 args");
        }
        return ObjectInspectorFactory
                .getStandardListObjectInspector(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
    }

    private void loadContents(DeferredObject[] args) throws HiveException {
        String fileName = args[0].get().toString();
        if (!fileName.contains("/")) {
            fileName = "./" + fileName;
        }
        String delim = args.length > 1 ? args[1].get().toString() : ";";
        try {
            contents = read(fileName, delim);
        } catch (IOException e) {
            throw new HiveException(e);
        }
    }

    @Override
    public Object evaluate(DeferredObject[] args) throws HiveException {
        if (contents == null) {
            loadContents(args);
        }
        return contents;
    }

    @Override
    public String getDisplayString(String[] args) {
        assert (args.length > 1);
        return "read_file(" + Joiner.on(',').join(args) + ")";
    }
}