svn commit: r1704370 - /tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java

[gr...@apache.org]

Author: grossws
Date: Mon Sep 21 17:20:36 2015
New Revision: 1704370

URL: http://svn.apache.org/viewvc?rev=1704370&view=rev
Log:
Add interruptable parsing example

See also http://stackoverflow.com/questions/31939851

Added:
    tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java

Added: tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java
URL: http://svn.apache.org/viewvc/tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java?rev=1704370&view=auto
==============================================================================
--- tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java (added)
+++ tika/trunk/tika-example/src/main/java/org/apache/tika/example/InterruptableParsingExample.java Mon Sep 21 17:20:36 2015
@@ -0,0 +1,91 @@
+/*
+ * 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.tika.example;
+
+import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import org.apache.tika.Tika;
+import org.apache.tika.exception.TikaException;
+import org.apache.tika.metadata.Metadata;
+import org.apache.tika.parser.ParseContext;
+import org.apache.tika.parser.Parser;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+/**
+ * This example demonstrates how to interrupt document parsing if
+ * some condition is met.
+ * <p>
+ * {@link InterruptingContentHandler} throws special exception as soon as
+ * find {@code query} string in parsed file.
+ *
+ * See also http://stackoverflow.com/questions/31939851
+ */
+public class InterruptableParsingExample {
+    private Tika tika = new Tika(); // for default autodetect parser
+
+    public boolean findInFile(String query, Path path) {
+        InterruptingContentHandler handler = new InterruptingContentHandler(query);
+
+        Metadata metadata = new Metadata();
+        ParseContext context = new ParseContext();
+        context.set(Parser.class, tika.getParser());
+
+        try (InputStream is = new BufferedInputStream(Files.newInputStream(path))) {
+            tika.getParser().parse(is, handler, metadata, context);
+        } catch (QueryMatchedException e) {
+            return true;
+        } catch (SAXException | TikaException | IOException e) {
+            // something went wrong with parsing...
+            e.printStackTrace();
+        }
+        return false;
+    }
+
+    class QueryMatchedException extends SAXException {
+    }
+
+    /**
+     * Trivial content handler that searched for {@code query} in characters send to it.
+     * <p>
+     * Throws {@link QueryMatchedException} when query string is found.
+     */
+    class InterruptingContentHandler extends DefaultHandler {
+        private String query;
+        private StringBuilder sb = new StringBuilder();
+
+        InterruptingContentHandler(String query) {
+            this.query = query;
+        }
+
+        @Override
+        public void characters(char[] ch, int start, int length) throws SAXException {
+            sb.append(new String(ch, start, length).toLowerCase());
+
+            if (sb.toString().contains(query))
+                throw new QueryMatchedException();
+
+            if (sb.length() > 2 * query.length())
+                sb.delete(0, sb.length() - query.length()); // keep tail with query.length() chars
+        }
+    }
+}