/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.ambari.server.serveraction.kerberos;
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
/**
* AbstractKerberosDataFileReader implements common code to read existing Kerberos data files.
* <p/>
* This class encapsulates a {@link org.apache.commons.csv.CSVParser} to read a CSV-formatted file.
*/
public abstract class AbstractKerberosDataFileReader implements Iterable<Map<String, String>> {
private File file;
private CSVParser csvParser = null;
/**
* Creates a new AbstractKerberosDataFileReader
* <p/>
* The file is opened upon creation, so there is no need to manually open it unless manually
* closed before using.
*
* @param file a File declaring where to write the data
* @throws java.io.IOException
*/
protected AbstractKerberosDataFileReader(File file) throws IOException {
this.file = file;
open();
}
/**
* Opens the data file for reading.
* <p/>
* This may be called multiple times and the appropriate action will occur depending on if the
* file has been previously opened or closed.
*
* @throws java.io.IOException if an error occurs while accessing the file
*/
public void open() throws IOException {
if (isClosed()) {
csvParser = CSVParser.parse(file, Charset.defaultCharset(), CSVFormat.DEFAULT.withHeader());
}
}
/**
* Tests this AbstractKerberosDataFileReader to see if the data file is closed.
*
* @return true if closed; otherwise false
*/
public boolean isClosed() {
return csvParser == null;
}
public void close() throws IOException {
if (csvParser != null) {
csvParser.close();
csvParser = null;
}
}
/**
* Gets an iterator to use to access the records in the data file.
* <p/>
* Each item is a Map of column names to values.
*
* @return an Iterator of records from the data file, each record is represented as a Map of
* column name (String) to column value (String)
*/
@Override
public Iterator<Map<String, String>> iterator() {
return new Iterator<Map<String, String>>() {
Iterator<CSVRecord> iterator = (csvParser == null) ? null : csvParser.iterator();
@Override
public boolean hasNext() {
return (iterator != null) && iterator.hasNext();
}
@Override
public Map<String, String> next() {
return (iterator == null) ? null : iterator.next().toMap();
}
@Override
public void remove() {
if (iterator != null) {
iterator.remove();
}
}
};
}
}