ixa.pipe.wikify.DBpediaSpotlightClient.java Source code

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Here is the source code for ixa.pipe.wikify.DBpediaSpotlightClient.java

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/**
 * Copyright 2011 Pablo Mendes, Max Jakob
 *
 * Licensed 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 ixa.pipe.wikify;

import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;

import org.dbpedia.spotlight.exceptions.AnnotationException;
import org.dbpedia.spotlight.model.Text;

import org.apache.commons.io.IOUtils;

import java.io.*;
import java.net.URLEncoder;

import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import java.io.StringReader;
import org.xml.sax.InputSource;

import org.apache.log4j.Logger;

/**
 * Simple web service-based annotation client for DBpedia Spotlight.
 *
 * @author pablomendes, Joachim Daiber
 */

public class DBpediaSpotlightClient {
    public Logger LOG = Logger.getLogger(this.getClass());

    private static final double CONFIDENCE = 0.0;
    private static final int SUPPORT = 0;
    private static final boolean COREFERENCE = false;

    // Create an instance of HttpClient.
    private static HttpClient client = new HttpClient();

    public String request(HttpMethod method) throws AnnotationException {

        String response = null;

        // Provide custom retry handler is necessary
        method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
                new DefaultHttpMethodRetryHandler(3, false));

        try {
            // Execute the method.
            int statusCode = client.executeMethod(method);

            if (statusCode != HttpStatus.SC_OK) {
                LOG.error("Method failed: " + method.getStatusLine());
            }

            // Read the response body.
            // // Deal with the response.
            // // Use caution: ensure correct character encoding and is not binary data
            InputStream responseBody = method.getResponseBodyAsStream();
            response = IOUtils.toString(responseBody, "UTF-8");

        } catch (HttpException e) {
            LOG.error("Fatal protocol violation: " + e.getMessage());
            throw new AnnotationException("Protocol error executing HTTP request.", e);
        } catch (IOException e) {
            LOG.error("Fatal transport error: " + e.getMessage());
            LOG.error(method.getQueryString());
            throw new AnnotationException("Transport error executing HTTP request.", e);
        } finally {
            // Release the connection.
            method.releaseConnection();
        }
        return response;

    }

    public Document extract(Text text, String host, String port) throws AnnotationException {

        LOG.info("Querying API.");
        String spotlightResponse = "";
        Document doc = null;
        try {
            String url = host + ":" + port + "/rest/annotate";
            PostMethod method = new PostMethod(url);
            method.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
            NameValuePair[] params = { new NameValuePair("text", text.text()),
                    new NameValuePair("confidence", Double.toString(CONFIDENCE)),
                    new NameValuePair("support", Integer.toString(SUPPORT)),
                    new NameValuePair("coreferenceResolution", Boolean.toString(COREFERENCE)) };
            method.setRequestBody(params);
            method.setRequestHeader(new Header("Accept", "text/xml"));
            spotlightResponse = request(method);
            doc = loadXMLFromString(spotlightResponse);
        } catch (javax.xml.parsers.ParserConfigurationException ex) {
        } catch (org.xml.sax.SAXException ex) {
        } catch (java.io.IOException ex) {
        }

        return doc;
    }

    public static Document loadXMLFromString(String xml)
            throws org.xml.sax.SAXException, java.io.IOException, javax.xml.parsers.ParserConfigurationException {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        InputSource is = new InputSource(new StringReader(xml));
        return builder.parse(is);
    }

}