com.px100systems.util.CsvParser.java Source code

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Here is the source code for com.px100systems.util.CsvParser.java

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/*
 * This file is part of Px100 Data.
 *
 * Px100 Data 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 3 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, see http://www.gnu.org/licenses/
 */
package com.px100systems.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.CSVStrategy;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.output.StringBuilderWriter;

/**
 * CSV parser.
 * 
 * @version 0.3 <br>Copyright (c) 2015 Px100 Systems. All Rights Reserved.<br>
 * @author Alex Rogachevsky
 */
public class CsvParser<T> {
    private CSVStrategy csvStrategy;

    /**
     * Default constructor (should be enough)
     */
    public CsvParser() {
        this(',', '"', '#');
    }

    /**
     * Custom constructor for non-standard CSV files
     * @param csvSeparator separator (,)
     * @param csvQuote quote (")
     * @param csvComment comment (#)
     */
    public CsvParser(char csvSeparator, char csvQuote, char csvComment) {
        csvStrategy = new CSVStrategy(csvSeparator, csvQuote, csvComment);
    }

    /**
     * Parsing into a list of beans (requires CSV header).
     *
     * @param content text
     * @param cls class
     * @return the list of beans of teh specified class.
     */
    public List<T> parse(String content, Class<T> cls) {
        List<T> result = new ArrayList<T>();

        CSVParser parser = new CSVParser(new BufferedReader(new StringReader(content)), csvStrategy);
        try {
            List<PropertyAccessor> properties = new ArrayList<PropertyAccessor>();
            for (String h : parser.getLine())
                properties.add(new PropertyAccessor(cls, h));

            if (!properties.isEmpty())
                for (String[] line = parser.getLine(); line != null; line = parser.getLine()) {
                    T object = cls.newInstance();
                    int fieldCount = 0;

                    for (int i = 0, n = properties.size(); i < n && i < line.length; i++)
                        if (line[i] != null && !line[i].trim().isEmpty()) {
                            properties.get(i).set(object, line[i]);
                            fieldCount++;
                        }

                    if (fieldCount > 0)
                        result.add(object);
                }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

        return result.isEmpty() ? null : result;
    }

    private String[] currentLine = null;
    private String[] header;

    /**
     * Parsing into a list of maps of fields (requires header)
     *
     * @param is imput stream
     * @return List of maps of {field, value} pairs
     */
    public Iterator<Map<String, String>> parseAsMap(InputStream is) {
        final CSVParser parser = new CSVParser(new BufferedReader(new InputStreamReader(is)), csvStrategy);
        try {
            header = parser.getLine();
            return new Iterator<Map<String, String>>() {
                @Override
                public boolean hasNext() {
                    try {
                        currentLine = parser.getLine();
                        return currentLine != null;
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                }

                @Override
                public Map<String, String> next() {
                    Map<String, String> row = new HashMap<String, String>();
                    for (int i = 0; i < header.length; i++)
                        row.put(header[i], currentLine[i]);
                    return row;
                }
            };
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Parsing into a list of lists (headerless)
     *
     * @param is input stream
     * @return a List of Lists of (String) fields
     */
    @SuppressWarnings("unused")
    public Iterator<List<String>> parseHeaderlessAsMap(InputStream is) {
        final CSVParser parser = new CSVParser(new BufferedReader(new InputStreamReader(is)), csvStrategy);
        return new Iterator<List<String>>() {
            @Override
            public boolean hasNext() {
                try {
                    currentLine = parser.getLine();
                    return currentLine != null;
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public List<String> next() {
                return Arrays.asList(currentLine);
            }
        };
    }

    /**
     * Export - the opposite of parseHeaderlessAsMap().
     *
     * @param lines of Strings
     * @return the CSV text
     */
    public String write(List<List<String>> lines) {
        StringBuilder result = new StringBuilder();

        Writer writer = new StringBuilderWriter(result);
        CSVPrinter printer = new CSVPrinter(writer, csvStrategy);
        try {
            for (List<String> line : lines)
                printer.println(line.toArray(new String[line.size()]));
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            IOUtils.closeQuietly(writer);
        }

        return result.toString();
    }
}