内存索引和lucene文件索引有什么区别?

检查此答案以比较FSDirectory和内存中的RAMDIrectory Comparison

如何使用RAMDirectory:

RAMDirectory idx = new RAMDirectory(); 
IndexWriterConfig iwc = new IndexWriterConfig(analyzer);
iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);
IndexWriter writer = new IndexWriter(idx, iwc);
Iterator<Map.Entry<String, String>> it = inputCategoryMap.entrySet().iterator();
    while (it.hasNext()) {
        Document doc = new Document();
        Map.Entry<String, String> pair = it.next();
        FieldType contentType = new FieldType();
        contentType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
        contentType.setStored(true);
        contentType.setTokenized(true);
        contentType.setStoreTermVectors(true);
        doc.add(new Field(TITLE, pair.getKey(), TextField.TYPE_STORED));
        doc.add(new Field(CONTENT, pair.getValue(),contentType ));
        dcmnts.add(doc);
    }
    writer.addDocuments(dcmnts);
    writer.commit();
    System.out.println("No of documents added in the index "+writer.maxDoc());
    writer.close();
   System.out.println("Size consumed by Ram  "+idx.ramBytesUsed()+"\nTime Consumed By Lucene  "+stopwatch.getTime(TimeUnit.SECONDS));

使用FSDirectory的方法相同。有一些小改动。

从FSDirectory复制索引的其他一些方法。。

private RAMDirectory(FSDirectory dir, boolean closeDir, IOContext context) throws IOException {
this();
for (String file : dir.listAll()) {
  if (!Files.isDirectory(dir.getDirectory().resolve(file))) {
    copyFrom(dir, file, file, context);
  }
}
if (closeDir) {
  dir.close();
}
}