ConfigFileReader.java

package util.text;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/*-
 * 
 * Advantage 
 * 1. It can read any config files of any format (csv, properties file or any text files).
 * 2 Format can be 
 * 2.a keys = values1, values2, values3
 * 2.b keys, values1, values2, values3    
 * 3. keys with space also works  
 * 4. One key multiple values
 * 5. Comment line starts with #. Even this can be made configuration
 * 6. The order of the keys is maintained. 
 * 7. The order of the values for any given key is also maintained.
 */
public class ConfigFileReader {

	private final String path;
	private final String keyValueSeparation;
	private final String valueSeparation;
	public final String COMMENT_LINE_STATRTS_WITH = "#";

	/**
	 * @param path
	 * @param keyValueSeparation
	 * @param valueSeparation
	 */
	public ConfigFileReader(String path, String keyValueSeparation, String valueSeparation) {
		this.path = path;
		this.keyValueSeparation = keyValueSeparation;
		this.valueSeparation = valueSeparation;
	}

	/**
	 * @param path
	 * @return
	 * @throws IOException
	 */
	public Map<String, List<String>> readkeyValues() throws IOException {
		// LinkedHashMap retains the order too
		Map<String, List<String>> map = new LinkedHashMap<String, List<String>>();
		BufferedReader br = null;
		try {
			FileInputStream fstream = new FileInputStream(path);
			// Get the object of DataInputStream
			DataInputStream in = new DataInputStream(fstream);
			br = new BufferedReader(new InputStreamReader(in));
			String strLine;
			// Read File line by line
			while ((strLine = br.readLine()) != null) {
				if (!strLine.trim().equalsIgnoreCase("")) {
					if (strLine.startsWith(COMMENT_LINE_STATRTS_WITH)) {
						continue;
					}
					String[] keyValues = strLine.split(keyValueSeparation);
					String key = keyValues[0].trim();
					StringBuilder valuesBuilder = new StringBuilder();
					if (keyValues.length > 1) {
						for (int i = 1; i < keyValues.length; i++) {
							valuesBuilder.append(keyValues[i]);
							valuesBuilder.append(valueSeparation);
						}
					}
					String values = valuesBuilder.toString();
					String[] multipleValues = values.split(valueSeparation);
					List<String> nultipleV = new ArrayList<String>();
					for (String v : multipleValues) {
						if (!v.trim().equalsIgnoreCase("")) {
							nultipleV.add(v.trim());
						}
					}
					map.put(key, nultipleV);
				}
			}
		} finally {
			br.close();
		}
		return map;
	}
}