MapFileReader.java 文件源码

public MapFileReader(List<String> paths, IndexToKey indexToKey, Class<? extends Writable> recordClass)
                throws IOException {

    this.indexToKey = indexToKey;
    this.recordClass = recordClass;
    this.readers = new MapFile.Reader[paths.size()];

    SequenceFile.Reader.Option[] opts = new SequenceFile.Reader.Option[0];

    Configuration config = new Configuration();
    for (int i = 0; i < paths.size(); i++) {
        readers[i] = new MapFile.Reader(new Path(paths.get(i)), config, opts);
        if (readers[i].getValueClass() != recordClass) {
            throw new UnsupportedOperationException("MapFile record class: " + readers[i].getValueClass()
                            + ", but got class " + recordClass + ", path = " + paths.get(i));
        }
    }

    recordIndexesEachReader = indexToKey.initialize(readers, recordClass);
}