com.google.gdt.util.HttpTranslator.java Source code

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Here is the source code for com.google.gdt.util.HttpTranslator.java

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/*
 * HttpTranslator.java
 *
 * Copyright (C) 2011,  Sanmoy Ray
 * 
 * This file is part of google-document-translator.
 *
 * Google Document Translator is not a product from Google. Neither it is endorsed nor it is supported by Google.
 * This is an open source and free software. you can redistribute it and/or modify it under the terms of the
 * GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License,
 * or(at your option) any later version.
 * 
 * Google Document Translator is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with Google Document Translator.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.google.gdt.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.StringReader;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;

import com.google.gdt.main.PreferenceModel;
import com.tecnick.htmlutils.htmlentities.HTMLEntities;

/**
 * Http translator uses http post method to send the content tobetranslated, and 
 * parse the response to get the translated output
 * 
 * @author Sanmoy
 *
 */
public class HttpTranslator implements Translator {

    /*
     * 
     */
    private PreferenceModel preferenceModel;

    /*
     * 
     */
    private static Logger logger = Logger.getLogger("HttpTranslator.class");

    /**
     * 
     */
    private String ametadata;

    /**
     * 
     */
    private String pmetadata;

    public HttpTranslator() {
        preferenceModel = PreferenceModel.getInstance();
        logger.log(Level.INFO, "proxy url : " + System.getProperty("http.proxyHost"));
        logger.log(Level.INFO, "proxy port : " + System.getProperty("http.proxyPort"));
        logger.log(Level.INFO, "to language : " + preferenceModel.getToLanguage());
        logger.log(Level.INFO, "from language : " + preferenceModel.getFromLanguage());
        pmetadata = TrConstants.PMETADATA.replaceAll("TranslatedLanguage",
                preferenceModel.getToLanguage().toString());
        if (preferenceModel.getFromLanguage().toString().equals("")) {
            ametadata = TrConstants.AMETADATA.replaceAll("SourceLanguage", "auto");
        } else {
            ametadata = TrConstants.AMETADATA.replaceAll("SourceLanguage",
                    preferenceModel.getFromLanguage().toString());
        }
    }

    /**
     * takes chinese text as input and translate it to english
     * @param inputText
     * @return translatedText
     */
    @Override
    public String translate(String inputText) throws Exception {
        String translatedText = "";

        if (null == inputText || inputText.equals(""))
            return translatedText;
        inputText = inputText.replaceAll("[\\n]", " gdtnewline ");
        inputText = URLEncoder.encode(inputText, "UTF-8");

        String body = ametadata + inputText + pmetadata;

        String response = doPost(body);
        translatedText = parseResponse(response);
        translatedText = translatedText.replaceAll("gdtnewline", "\n");
        return HTMLEntities.unhtmlentities(translatedText);
    }

    /**
     * parse the response from google server and extracts the desired translated Text
     * @param response
     * @return translatedText
     */
    private String parseResponse(String response) {
        //      System.out.println(response);
        String translatedText = "";
        InputSource is = new InputSource(new StringReader(response));
        SAXReader reader = new SAXReader();
        Document doc = null;
        try {
            doc = reader.read(is);
        } catch (DocumentException e) {
            logger.log(Level.SEVERE, "Not able to parse response : " + response, e);
            return "";
        }

        Element root = doc.getRootElement();
        for (Iterator i = root.elementIterator(); i.hasNext();) {
            Element element = (Element) i.next();
            translatedText += element.getText();
        }
        return translatedText;
    }

    /**
     * connects google server to get the translation
     * @author sanmoy
     * @param body
     * @return response
     */
    private String doPost(String body) throws IOException {
        //      logger.log(Level.INFO, "request message body : "+body);
        // Send the request
        URL url = new URL(TrConstants.TRANSURL);
        URLConnection conn = url.openConnection();

        conn.setRequestProperty("User-Agent", TrConstants.UAGENT);
        conn.setDoOutput(true);

        // write parameters
        OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
        writer.write(body);
        writer.flush();

        // Get the response
        StringBuffer answer = new StringBuffer();
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            answer.append(line);
        }
        writer.close();
        reader.close();

        // Output the response and truncate doctype
        String answerString = answer.toString().substring(15);
        //      logger.log(Level.INFO, "Answer String from google : "+answerString);
        int beginIndex = answerString.indexOf("span id=result_box");
        int endIndex = answerString.lastIndexOf("</span></span>");
        String response = body.substring(ametadata.length(), body.length() - pmetadata.length());
        try {
            response = answerString.substring(beginIndex + 37, endIndex + 14);
        } catch (Exception e) {
            logger.log(Level.SEVERE, "not able to translate the input : " + response, e);
            return "<span>" + response + "</span>";
        }
        //      System.out.println("<span>"+response);
        return "<span>" + response;
    }
}