Hi, I'm trying to use Lucene in my Android project. To start with I've
created a small demo app. It works with .txt files but I need to work with
.pdf. So analyzing my code I understand that it will have some issues with
.pdfs due to memory management. However the question I want to ask here is
not related to memory but to hit highlighting. It works now but using of
`Highlighter` class with pdfs is not what I want. So to implement my own
highlighting I need to know some kind of coordinates of found words in the
text. How can I get them? I'm using lucene 4.4.0 while all of the examples
like here are for much older versions. Here is my code:
public class MainActivity extends Activity {
//-----------------------------------------------------------------------------------------------------
//
// Constants
//
//-----------------------------------------------------------------------------------------------------
public static final String FIELD_PATH = "path";
public static final String FIELD_CONTENTS = "contents";
//-----------------------------------------------------------------------------------------------------
//
// Fields
//
//-----------------------------------------------------------------------------------------------------
private EditText mEditText;
private TextView mTextView;
//-----------------------------------------------------------------------------------------------------
//
// Methods
//
//-----------------------------------------------------------------------------------------------------
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViews();
initViews();
createIndex();
}
private void findViews() {
mEditText = (EditText) findViewById(R.id.activity_main_edittext);
mTextView = (TextView) findViewById(R.id.activity_main_textview);
}
private void initViews() {
mEditText.setOnEditorActionListener(mEditorActionListener);
}
private void performSearch(String searchString) {
try {
Directory directory =
NIOFSDirectory.open(getExternalFilesDir(null));
DirectoryReader ireader =
DirectoryReader.open(directory);
IndexSearcher isearcher = new IndexSearcher(ireader);
Analyzer analyzer = new
StandardAnalyzer(Version.LUCENE_44);
QueryParser queryParser = new
AnalyzingQueryParser(Version.LUCENE_44, FIELD_CONTENTS, analyzer);
Query query = queryParser.parse(searchString);
TopDocs topDocs = isearcher.search(query, null,
1000);
ScoreDoc[] docs = topDocs.scoreDocs;
StringBuilder result = new StringBuilder();
StringBuilder debugInfo = new StringBuilder();
debugInfo.append("Number of hits: ");
debugInfo.append(docs.length);
debugInfo.append("\n");
// Iterate through the results:
for (int i = 0; i < docs.length; i++) {
Document hitDoc =
isearcher.doc(docs[i].doc);
String path = hitDoc.get(FIELD_PATH);
debugInfo.append("Path: ");
debugInfo.append(path);
debugInfo.append("\n");
result.append("-------------------------------------------------------");
result.append("File: ");
result.append(path);
result.append("-------------------------------------------------------");
result.append("<br>");
String content = hitDoc.get(FIELD_CONTENTS);
QueryScorer scorer = new QueryScorer(query);
Highlighter highlighter = new
Highlighter(new SimpleHTMLFormatter("", ""), scorer);
highlighter.setTextFragmenter(new
SimpleSpanFragmenter(scorer, Integer.MAX_VALUE));
String highlighted =
highlighter.getBestFragment(analyzer, FIELD_CONTENTS, content);
result.append("-------------------------------------------------------");
result.append("Contents: ");
result.append("-------------------------------------------------------");
result.append("<br>");
result.append(highlighted);
result.append("<br><br><br>");
}
//not working
/*PostingsHighlighter highlighter = new
PostingsHighlighter();
String highlights[] =
highlighter.highlight(FIELD_CONTENTS, query, isearcher, topDocs);*/
mTextView.setText(Html.fromHtml(result.toString()));
Log.d(getClass().getSimpleName(),
debugInfo.toString());
} catch (Exception e) {
e.printStackTrace();
Log.e(getClass().getSimpleName(), e.getMessage());
}
}
private void createIndex() {
try {
//Create directory for index.
Directory indexDirectory = new
NIOFSDirectory(getExternalFilesDir(null));
Analyzer analyzer = new
StandardAnalyzer(Version.LUCENE_44);
IndexWriterConfig config = new
IndexWriterConfig(Version.LUCENE_44, analyzer);
config.setOpenMode(OpenMode.CREATE);
IndexWriter indexWriter = new
IndexWriter(indexDirectory, config);
//Loop through files in specified directory and
adding them to index.
File dir = new
File(Environment.getExternalStorageDirectory() + "/lucene");
File[] files = dir.listFiles();
for (File file : files) {
Document document = new Document();
{
FieldType fieldType = new
FieldType(TextField.TYPE_STORED);
fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
String path =
file.getCanonicalPath();
document.add(new Field(FIELD_PATH,
path, fieldType));
}
{
FieldType fieldType = new
FieldType(TextField.TYPE_STORED);
fieldType.setIndexed(true);
fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
fieldType.setStored(true);
fieldType.setStoreTermVectors(true);
fieldType.setTokenized(true);
fieldType.setStoreTermVectorOffsets(true);
String content = readFully(new
FileReader(file)); //we can't store Reader objects but we need to be able to
access the content for highlighting
document.add(new
Field(FIELD_CONTENTS, content, fieldType));
}
indexWriter.addDocument(document);
}
indexWriter.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public static String readFully(Reader reader) throws IOException {
char[] arr = new char[8*1024]; // 8K at a time
StringBuffer buf = new StringBuffer();
int numChars;
while ((numChars = reader.read(arr, 0, arr.length)) > 0) {
buf.append(arr, 0, numChars);
}
return buf.toString();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
//-----------------------------------------------------------------------------------------------------
//
// Listeners
//
//-----------------------------------------------------------------------------------------------------
private OnEditorActionListener mEditorActionListener = new
OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId,
KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_SEARCH) {
performSearch(v.getText().toString());
return true;
}
return false;
}
};
}
So how can I get hit coordinates and maybe you have any other advices what
I'm doing wrong? This is rather common task I think so it must be rather
simple.
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