org.sociotech.communitymashup.source.readability.apiwrapper.ReadabilityAPIWrapper.java Source code

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Here is the source code for org.sociotech.communitymashup.source.readability.apiwrapper.ReadabilityAPIWrapper.java

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/*******************************************************************************
 * Copyright (c) 2013 Peter Lachenmaier.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Peter Lachenmaier - Design and initial implementation
 ******************************************************************************/
package org.sociotech.communitymashup.source.readability.apiwrapper;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.sociotech.communitymashup.source.readability.apiwrapper.items.ReadabilityResult;

import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;

/**
 * Wrapper for the readability api.
 * 
 * @author Peter Lachenmaier
 */
public class ReadabilityAPIWrapper {

    /** The parser. */
    private final JsonParser parser = new JsonParser();

    /**
     * The parameter to provide the url of the website to parse
     */
    private final static String URL_PARAMETER = "url";

    /**
     * The parameter to provide the readabillity api key
     */
    private final static String TOKEN_PARAMETER = "token";

    /**
     * Url of the participants api
     */
    private final String baseUrl;

    /**
     * Api Key
     */
    private final String key;

    /**
     * Returns the used base url.
     * 
     * @return The used base url.
     */
    public String getBaseUrl() {
        return baseUrl;
    }

    /**
     * Returns the used api key.
     * 
     * @return The used api key.
     */
    public String getKey() {
        return key;
    }

    /**
     * Intitialises a new api wrapper with the given base url and the api key.
     * 
     * @param baseUrl
     *            Url of the api
     * @param apiKey
     *            Secret to access the api
     */
    public ReadabilityAPIWrapper(String baseUrl, String apiKey) {
        this.baseUrl = baseUrl;
        this.key = apiKey;
    }

    /**
     * Calls the readablity parser api for the given url and returns the result.
     * 
     * @param url
     *            Url of the website to be parsed by readablity
     * @return The parsed result or null in error case.
     */
    public ReadabilityResult getReadablityVersionOf(String url) {
        if (url == null) {
            return null;
        }

        String requestUrl;

        try {
            requestUrl = baseUrl + "?" + URL_PARAMETER + "=" + URLEncoder.encode(url, "UTF-8") + "&"
                    + TOKEN_PARAMETER + "=" + key;
        } catch (UnsupportedEncodingException e) {
            return null;
        }

        // process request
        String result = doGet(requestUrl);

        if (result == null) {
            return null;
        }

        // parse result
        JsonElement json = parser.parse(result);

        // unmarshall the json
        ReadabilityResult resultObject = unmarshall(ReadabilityResult.class, json);

        return resultObject;
    }

    /**
     * Does a get request at the given url and returns the result as string.
     * 
     * @param url
     *            Url to get
     * @return The result as string null in error case.
     */
    private String doGet(String url) {
        // System.out.println("calling: " + url);

        String result = null;

        HttpClient httpClient = new DefaultHttpClient();

        HttpGet get = new HttpGet(url);

        ResponseHandler<String> responseHandler = new BasicResponseHandler();

        try {
            result = httpClient.execute(get, responseHandler);
        } catch (Exception e) {
            // do nothing
        } finally {
            // client is no longer needed
            httpClient.getConnectionManager().shutdown();
        }

        // System.out.println("got: " + result);

        return result;
    }

    @SuppressWarnings("unused")
    private String doPost(String url, Map<String, String> parameterMap) {
        String result = null;

        HttpClient httpClient = new DefaultHttpClient();

        HttpPost post = new HttpPost(url);

        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);

        // add all post parameter
        for (String key : parameterMap.keySet()) {
            nameValuePairs.add(new BasicNameValuePair(key, parameterMap.get(key)));
        }

        ResponseHandler<String> responseHandler = new BasicResponseHandler();

        try {
            post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            result = httpClient.execute(post, responseHandler);
        } catch (Exception e) {
            // do nothing
        } finally {
            // client is no longer needed
            httpClient.getConnectionManager().shutdown();
        }

        return result;
    }

    /**
     * Unmarshalls given json content of the given type.
     * 
     * @param type
     *            The result Type
     * @param json
     *            Json to be unmarshalled
     * 
     * @return Unmarshalled json content as object of the given type
     */
    protected <T> T unmarshall(Class<T> type, JsonElement json) {
        Gson gson = getGsonBuilder().create();
        return gson.fromJson(json, type);
    }

    /**
     * Unmarshalls given json content as a list of the given type.
     * 
     * @param type
     *            The result Type
     * @param json
     *            Json to be unmarshalled
     * 
     * @return Unmarshalled json content as list of objects of the given type
     */
    protected <T> List<T> unmarshallList(Class<T> type, JsonElement json) {
        List<T> retValue = new LinkedList<T>();
        if (json.isJsonArray()) {
            for (JsonElement element : json.getAsJsonArray()) {
                retValue.add(unmarshall(type, element));
            }
        }
        return retValue;
    }

    /**
     * Gets the gson builder.
     * 
     * @return the gson builder
     */
    protected GsonBuilder getGsonBuilder() {
        GsonBuilder builder = new GsonBuilder();

        builder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);

        return builder;
    }
}