edu.jhu.hlt.alnc.ALNCFileConverter.java Source code

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Here is the source code for edu.jhu.hlt.alnc.ALNCFileConverter.java

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/*
 * Copyright 2012-2015 Johns Hopkins University HLTCOE. All rights reserved.
 * See LICENSE in the project root directory.
 */
package edu.jhu.hlt.alnc;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.stream.Stream;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Class that can be used to convert ALNC files to {@link ALNCArticleBean} objects. 
 * <br>
 * <br>
 * Each file, as of 2015/2/23, contain one JSON object per line.
 */
public class ALNCFileConverter implements AutoCloseable {

    private static final ObjectMapper om = new ObjectMapper();

    private final InputStream is;
    private final InputStreamReader isr;
    private final BufferedReader br;

    /**
     * Wrap an {@link InputStream} that represents ALNC JSON, one JSON object per line.
     *
     * @param is an {@link InputStream} over properly formed ALNC JSON data
     */
    public ALNCFileConverter(InputStream is) {
        this.is = is;
        this.isr = new InputStreamReader(is, StandardCharsets.UTF_8);
        this.br = new BufferedReader(this.isr, 1024 * 8 * 8 * 4);
    }

    public ALNCFileConverter(Path path) throws IOException {
        this(Files.newInputStream(path));
    }

    /**
     * Return a {@link Stream} of {@link ALNCArticleBean} objects. This stream should be
     * closed when processing is complete.
     * <br>
     * <br>
     * This method can throw an unchecked exception. This will
     * occur when the underlying InputStream does not represent ALNC JSON data.
     * 
     * @return a {@link Stream} of {@link ALNCArticleBean} objects.
     * @throws IOException if there is an issue reading the underlying archive.
     * @throws UncheckedIOException if there is an issue with the conversion. 
     */
    public Stream<ALNCArticleBean> stream() throws IOException {
        return this.br.lines().sequential().map(l -> {
            try {
                // unlikely to throw, provided stream is corrent JSON objects.
                return om.readValue(l, ALNCArticleBean.class);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        });
    }

    @Override
    public void close() throws IOException {
        this.br.close();
        this.isr.close();
        this.is.close();
    }
}