java/examples/lucene/example.ts

Bridge API to connect with existing Java APIs.

#!/usr/bin/env node

import java, { JavaObject } from "java";
import findRoot from "find-root";
import path from "node:path";

const root = findRoot(__dirname);

java.classpath.push(path.join(root, "libs/lucene-core-7.4.0.jar"));
java.classpath.push(path.join(root, "libs/lucene-analyzers-common-7.4.0.jar"));
java.classpath.push(path.join(root, "libs/lucene-queryparser-7.4.0.jar"));

const idx = java.newInstanceSync("org.apache.lucene.store.RAMDirectory");
const analyzer = java.newInstanceSync("org.apache.lucene.analysis.standard.StandardAnalyzer");
const writerConfig = java.newInstanceSync("org.apache.lucene.index.IndexWriterConfig", analyzer);
const writer = java.newInstanceSync("org.apache.lucene.index.IndexWriter", idx, writerConfig);
const queryParser = java.newInstanceSync("org.apache.lucene.queryparser.classic.QueryParser", "content", analyzer);

writer.addDocumentSync(
  createDocument(
    "Theodore Roosevelt",
    "It behooves every man to remember that the work of the " +
    "critic, is of altogether secondary importance, and that, " +
    "in the end, progress is accomplished by the man who does " +
    "things."
  )
);
writer.addDocumentSync(
  createDocument(
    "Friedrich Hayek",
    "The case for individual freedom rests largely on the " +
    "recognition of the inevitable and universal ignorance " +
    "of all of us concerning a great many of the factors on " +
    "which the achievements of our ends and welfare depend."
  )
);
writer.addDocumentSync(
  createDocument(
    "Ayn Rand",
    "There is nothing to take a man's freedom away from " +
    "him, save other men. To be free, a man must be free " +
    "of his brothers."
  )
);
writer.addDocumentSync(
  createDocument("Mohandas Gandhi", "Freedom is not worth having if it does not connote " + "freedom to err.")
);

writer.closeSync();

const searcher = java.newInstanceSync(
  "org.apache.lucene.search.IndexSearcher",
  java.callStaticMethodSync("org.apache.lucene.index.DirectoryReader", "open", idx)
);

search(searcher, "freedom");
search(searcher, "free");
search(searcher, "progress or achievements");
java.stop();

function createDocument(title: string, content: string): JavaObject {
  const fieldStoreYes = java.callStaticMethodSync("org.apache.lucene.document.Field$Store", "valueOf", "YES");
  const doc = java.newInstanceSync("org.apache.lucene.document.Document");
  doc.addSync(java.newInstanceSync("org.apache.lucene.document.TextField", "title", title, fieldStoreYes));
  doc.addSync(java.newInstanceSync("org.apache.lucene.document.TextField", "content", content, fieldStoreYes));
  return doc;
}

function search(searcher: JavaObject, queryString: string): void {
  const query = queryParser.parseSync(queryString);
  const topDocs = searcher.searchSync(query, 10);

  console.log("Found " + topDocs.totalHits + ' hits for query "' + queryString + '".');
  const scoreDocs = topDocs.scoreDocs;
  for (let i = 0; i < topDocs.scoreDocs.length; i++) {
    const docId = scoreDocs[i].doc;
    const doc = searcher.docSync(docId);
    console.log("  " + (i + 1) + ". " + doc.getSync("title"));
  }
}