com.metamx.druid.guava.GuavaUtils.java Source code

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Here is the source code for com.metamx.druid.guava.GuavaUtils.java

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/*
 * Druid - a distributed column store.
 * Copyright (C) 2012  Metamarkets Group Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package com.metamx.druid.guava;

import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.Iterables;
import com.google.common.io.CharStreams;
import com.google.common.io.InputSupplier;

import javax.annotation.Nullable;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;
import java.util.zip.GZIPInputStream;

/**
 */
public class GuavaUtils {
    public static Function<String, String> formatFunction(final String formatString) {
        return new Function<String, String>() {
            @Override
            public String apply(@Nullable String input) {
                return String.format(formatString, input);
            }
        };
    }

    public static InputSupplier<BufferedReader> joinFiles(final File... files) {
        return joinFiles(Arrays.asList(files));
    }

    public static InputSupplier<BufferedReader> joinFiles(final List<File> files) {

        return new InputSupplier<BufferedReader>() {
            @Override
            public BufferedReader getInput() throws IOException {
                return new BufferedReader(CharStreams
                        .join(Iterables.transform(files, new Function<File, InputSupplier<InputStreamReader>>() {
                            @Override
                            public InputSupplier<InputStreamReader> apply(final File input) {
                                return new InputSupplier<InputStreamReader>() {
                                    @Override
                                    public InputStreamReader getInput() throws IOException {
                                        InputStream baseStream = new FileInputStream(input);
                                        if (input.getName().endsWith(".gz")) {
                                            baseStream = new GZIPInputStream(baseStream);
                                        }

                                        return new InputStreamReader(baseStream, Charsets.UTF_8);
                                    }
                                };
                            }
                        })).getInput());
            }
        };
    }
}