de.cosmocode.palava.core.inject.csv.CsvConverter.java Source code

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Here is the source code for de.cosmocode.palava.core.inject.csv.CsvConverter.java

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/**
 * Copyright 2010 CosmoCode GmbH
 *
 * Licensed 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 de.cosmocode.palava.core.inject.csv;

import java.util.Arrays;
import java.util.List;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.io.Closeables;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.TypeConverter;

import de.cosmocode.commons.io.CloseableIterator;

/**
 * A {@link TypeConverter} which reads csv files and produces
 * {@link List}s of {@link String} arrays.
 * 
 * <h4>Defaults</h4>
 * 
 * <table>
 *   <tr>
 *     <th>Separator</th>
 *     <td>,</td>
 *   </tr>
 *   <tr>
 *     <th>Quote char</th>
 *     <td>"</td>
 *   </tr>
 *   <tr>
 *     <th>Escape char</th>
 *     <td>\</td>
 *   </tr>
 * </table>
 * 
 * <h4>Usage</h4>
 * <p>
 *   application.properties<br />
 *   {@code my.data = csv:file:data.csv}
 * </p>
 * 
 * <h4>Configuration</h4>
 * <p>
 *   Separator, quote char and escape char can be configured using the following
 *   syntax:<br />
 *   {@code csv:<separator>:<quote>:<escape>:<pathToFile>}<br />
 * </p>
 * 
 * <p>
 *   Example:<br />
 *   {@code my.data = csv:\t:':#:file:data.csv}<br />
 * </p>
 * 
 * <p>
 *   There is no need to specify every three characters, if you only want to change
 *   the separator, just leave the rest:<br />
 *   {@code my.data = csv:\t:file:data.csv}
 * </p>
 * 
 * <p>
 *   <strong>Note</strong>: The given file must fulfill the following requirements:
 *   <ul>
 *     <li>must contain at least one line</li>
 *     <li>must contain a header line (first line)</li>
 *     <li>must not contain any line that is longer than the header</li>
 *   </ul>
 *   Lines that are smaller than the header will be filled with empty strings,
 *   to match the header size.
 * </p>
 * 
 * @since 2.9
 * @author Willi Schoenborn
 */
public final class CsvConverter implements TypeConverter {

    public static final TypeLiteral<List<String[]>> LITERAL = new TypeLiteral<List<String[]>>() {
    };

    private final CsvIteratorConverter converter = new CsvIteratorConverter();

    @Override
    public List<String[]> convert(String value, TypeLiteral<?> toType) {
        final CloseableIterator<String[]> iterator = converter.convert(value, CsvIteratorConverter.LITERAL);

        try {
            final List<String[]> lines = Lists.newArrayList(iterator);
            Preconditions.checkArgument(lines.size() > 0, "%s is empty", value);

            final String[] header = lines.get(0);

            for (int index = 1; index < lines.size(); index++) {
                final String[] line = lines.get(index);

                if (line.length == header.length) {
                    continue;
                } else if (line.length < header.length) {
                    final String[] copy = new String[header.length];
                    Arrays.fill(copy, "");
                    System.arraycopy(line, 0, copy, 0, line.length);
                    lines.set(index, copy);
                } else {
                    // we skip the header, but we count from line 1
                    throw new IllegalArgumentException(String.format("Line #%s is too long", index - 1));
                }
            }

            return lines;
        } finally {
            Closeables.closeQuietly(iterator);
        }
    }

}