au.com.jwatmuff.eventmanager.util.CSVBeanReader.java Source code

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Here is the source code for au.com.jwatmuff.eventmanager.util.CSVBeanReader.java

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/*
 * EventManager
 * Copyright (c) 2008-2017 James Watmuff & Leonard Hall
 *
 * 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 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 au.com.jwatmuff.eventmanager.util;

import au.com.bytecode.opencsv.CSVReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.ArrayList;
import java.util.Collection;
import org.apache.commons.beanutils.WrapDynaBean;
import org.apache.log4j.Logger;

/**
 * Reads rows of a CSV file and creates a Java bean for each row, populating the
 * properties of the bean from the fields of the row according to a
 * user-specified mapping.
 * 
 * @author James
 */
public class CSVBeanReader<T> {
    private static Logger log = Logger.getLogger(CSVBeanReader.class);

    private CSVReader reader;
    private Map<String, String> mapping;
    private Class<T> clazz;
    private Collection<String> requiredColumns;

    private boolean headerRead = false;
    private String[] propertyNames;

    /** Creates a new instance of CSVBeanReader */
    public CSVBeanReader(CSVReader reader, Map<String, String> mapping, Class<T> clazz) {
        this(reader, mapping, clazz, new ArrayList<String>());
    }

    public CSVBeanReader(CSVReader reader, Map<String, String> mapping, Class<T> clazz,
            Collection<String> requiredColumns) {
        this.reader = reader;
        this.clazz = clazz;
        this.mapping = new HashMap<String, String>(mapping);
        this.requiredColumns = new ArrayList<String>(requiredColumns);
    }

    public T readBean() {
        if (!headerRead)
            readHeader();

        T bean;
        try {
            bean = (T) clazz.newInstance();
            WrapDynaBean dynaBean = new EnumConvertingWrapDynaBean(bean);

            String[] line = reader.readNext();
            if (line == null)
                return null;

            for (int i = 0; i < line.length; i++) {
                if (propertyNames[i] != null) {
                    dynaBean.set(propertyNames[i], line[i]);
                }
            }
        } catch (InstantiationException e) {
            throw new RuntimeException("Unable to create bean of class " + clazz, e);
        } catch (IllegalAccessException iae) {
            throw new RuntimeException("Unable to create bean of class " + clazz, iae);
        } catch (IOException ioe) {
            log.error("IOException while reading from CSV file", ioe);
            return null;
        }

        return bean;
    }

    public List<T> readBeans() {
        List<T> beans = new ArrayList<T>();

        T bean;
        while ((bean = readBean()) != null)
            beans.add(bean);

        return beans;
    }

    private void readHeader() {
        headerRead = true;

        try {
            String[] line = reader.readNext();
            if (line == null)
                return;

            propertyNames = new String[line.length];

            int i = 0;
            for (String value : line) {
                String columnPattern = findFirstMatchingColumnPattern(value);
                requiredColumns.remove(columnPattern);
                propertyNames[i] = mapping.get(columnPattern);
                log.debug("Mapped column " + value + " to property " + propertyNames[i]);
                i++;
            }

        } catch (IOException e) {
            throw new RuntimeException("Unable to read CSV file", e);
        }

        if (!requiredColumns.isEmpty()) {
            StringBuilder sb = new StringBuilder("CSV did not contain required columns: ");
            int i = 0;
            for (String heading : requiredColumns) {
                if (i++ > 0)
                    sb.append(", ");
                sb.append(heading);
            }
            throw new RuntimeException(sb.toString());
        }
    }

    private String findFirstMatchingColumnPattern(String columnName) {
        for (String columnPattern : mapping.keySet())
            if (columnName.matches("(?i).*" + columnPattern + ".*"))
                return columnPattern;

        return null;
    }
}