com.moesol.gwt.maps.client.tms.FeatureReader.java Source code

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Here is the source code for com.moesol.gwt.maps.client.tms.FeatureReader.java

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/**
 * (c) Copyright, Moebius Solutions, Inc., 2012
 *
 *                        All Rights Reserved
 *
 * LICENSE: GPLv3
 */
package com.moesol.gwt.maps.client.tms;

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;
import com.google.gwt.json.client.JSONArray;
import com.google.gwt.json.client.JSONNumber;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONString;
import com.google.gwt.json.client.JSONValue;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.moesol.gwt.maps.shared.Feature;

public class FeatureReader {
    public static class Builder {
        private final String m_server;
        private final String m_urlPattern;
        private String m_root;
        private String m_titlePropertyName = "title";
        private String m_iconPropertyName = "icon";
        private String m_latPropertyName = "lat";
        private String m_lngPropertyName = "lng";
        private PropertyConverter m_iconPropertyConverter;

        public Builder(String server, String urlPattern) {
            m_server = server;
            m_urlPattern = urlPattern;
        }

        public Builder root(String root) {
            m_root = root;
            return this;
        }

        public Builder titleProperty(String titleProperty) {
            m_titlePropertyName = titleProperty;
            return this;
        }

        public Builder latProperty(String latProperty) {
            m_latPropertyName = latProperty;
            return this;
        }

        public Builder lngProperty(String lngProperty) {
            m_lngPropertyName = lngProperty;
            return this;
        }

        public Builder iconProperty(String iconProperty) {
            m_iconPropertyName = iconProperty;
            return this;
        }

        public Builder iconProperty(String iconProperty, PropertyConverter converter) {
            m_iconPropertyName = iconProperty;
            m_iconPropertyConverter = converter;
            return this;
        }

        public FeatureReader build() {
            String baseUrlPattern = m_urlPattern.replace("{server}", m_server);
            return new FeatureReader(baseUrlPattern, m_root, m_titlePropertyName, m_latPropertyName,
                    m_lngPropertyName, m_iconPropertyName, m_iconPropertyConverter);
        }
    }

    private final String m_root;

    private final String m_titlePropertyName;
    private final String m_iconPropertyName;

    private final String m_baseUrlPattern;

    private PropertyConverter m_iconPropertyConverter;

    private String m_latPropertyName;

    private String m_lngPropertyName;

    private FeatureReader(String baseUrlPattern, String root, String titleAttributeName, String latAttributeName,
            String lngAttributeName, String iconAttributeName, PropertyConverter iconPropertyConverter) {
        m_baseUrlPattern = baseUrlPattern;
        m_root = root;
        m_titlePropertyName = titleAttributeName;
        m_latPropertyName = latAttributeName;
        m_lngPropertyName = lngAttributeName;
        m_iconPropertyName = iconAttributeName;
        m_iconPropertyConverter = iconPropertyConverter;
    }

    public void getFeatures(int level, double lat, double lng, final AsyncCallback<List<Feature>> callback) {
        String url = m_baseUrlPattern.replace("{level}", String.valueOf(level))
                .replace("{lat}", String.valueOf(lat)).replace("{lng}", String.valueOf(lng));
        RequestBuilder requestBuilder = new RequestBuilder(RequestBuilder.GET, url);
        requestBuilder.setHeader("Accept", "application/json");
        try {
            requestBuilder.sendRequest(null, new RequestCallback() {
                @Override
                public void onResponseReceived(Request request, Response response) {
                    callback.onSuccess(parseFeatures(response.getText()));
                }

                @Override
                public void onError(Request request, Throwable exception) {
                    callback.onFailure(exception);
                }
            });
        } catch (RequestException e) {
            callback.onFailure(e);
        }
    }

    private List<Feature> parseFeatures(String text) {
        ArrayList<Feature> features = new ArrayList<Feature>();
        try {
            JSONArray array = null;
            JSONValue parsedValue = JSONParser.parseStrict(text);
            if (m_root != null) {
                // should be an object with an array with property m_root
                JSONObject rootObj = parsedValue.isObject();
                if (rootObj != null) {
                    JSONValue arrayValue = rootObj.get(m_root);
                    if (arrayValue != null) {
                        array = arrayValue.isArray();
                    }
                }
            } else {
                array = parsedValue.isArray();
            }

            if (array != null) {
                for (int i = 0; i < array.size(); i++) {
                    JSONObject obj = (JSONObject) array.get(i);

                    String title = getStringProperty(m_titlePropertyName, obj);
                    double lat = getDoubleProperty(m_latPropertyName, obj);
                    double lng = getDoubleProperty(m_lngPropertyName, obj);
                    String iconUrl = getStringProperty(m_iconPropertyName, obj);
                    if (m_iconPropertyConverter != null) {
                        iconUrl = m_iconPropertyConverter.convert(iconUrl);
                    }
                    Feature feature = new Feature.Builder(title, lat, lng).iconUrl(iconUrl).build();
                    features.add(feature);
                }
            }
        } catch (Throwable t) {
            Logger.getLogger(FeatureReader.class.getName()).log(Level.SEVERE, "Failed parsing features", t);
        }

        return features;
    }

    private double getDoubleProperty(String propertyName, JSONObject obj) {
        JSONValue jsonValue = obj.get(propertyName);
        if (jsonValue != null) {
            JSONNumber jsonNumber = jsonValue.isNumber();
            if (jsonNumber != null) {
                return jsonNumber.doubleValue();
            }
        }

        return 0.0;
    }

    private String getStringProperty(String propertyName, JSONObject obj) {
        JSONValue jsonValue = obj.get(propertyName);
        if (jsonValue != null) {
            JSONString jsonString = jsonValue.isString();
            if (jsonString != null) {
                return jsonString.stringValue();
            }
        }

        return null;
    }

    public interface PropertyConverter {
        public String convert(String value);
    }
}