opennlp.tools.formats.convert.FileToStringSampleStream.java Source code

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Here is the source code for opennlp.tools.formats.convert.FileToStringSampleStream.java

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/*
 * 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 opennlp.tools.formats.convert;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;

import opennlp.tools.util.FilterObjectStream;
import opennlp.tools.util.ObjectStream;

/**
 * Provides the ability to read the contents of files
 * contained in an object stream of files.
 *
 */
public class FileToStringSampleStream extends FilterObjectStream<File, String> {

    private final Charset encoding;

    /**
     * Creates a new file-to-string sample stream.
     * @param samples The {@link ObjectStream} containing the files.
     * @param encoding The {@link Charset} encoding of the files.
     */
    public FileToStringSampleStream(ObjectStream<File> samples, Charset encoding) {
        super(samples);

        this.encoding = encoding;
    }

    /**
     * Reads the contents of a file to a string.
     * @param textFile The {@link File} to read.
     * @param encoding The {@link Charset} for the file.
     * @return The string contents of the file.
     * @throws IOException Thrown if the file cannot be read.
     */
    private static String readFile(File textFile, Charset encoding) throws IOException {

        Reader in = new BufferedReader(new InputStreamReader(new FileInputStream(textFile), encoding));

        StringBuilder text = new StringBuilder();

        try {
            char[] buffer = new char[1024];
            int length;
            while ((length = in.read(buffer, 0, buffer.length)) > 0) {
                text.append(buffer, 0, length);
            }
        } finally {
            try {
                in.close();
            } catch (IOException e) {
                // sorry that this can fail!
            }
        }

        return text.toString();
    }

    @Override
    public String read() throws IOException {

        File sampleFile = samples.read();

        if (sampleFile != null) {
            return readFile(sampleFile, encoding);
        } else {
            return null;
        }
    }

}