在GWT / Java的SuggestBox中建议地址 [英] Suggest Addresses in a SuggestBox in GWT/Java

问题描述

我想定义一个 SuggestBox ，其行为与 Google地图：开始输入时，会出现以输入字母开头的实际地址。

我认为，我需要使用 Geocoder.getLocations（String address，LocationCallback callback）方法，但我不知道如何将它与提示框所需的oracle联系起来以提出建议。

您可以给我一些想法，我该如何将 getLocations 方法与 SuggestOracle SuggestBox ，它有自己的 SuggestOracle 。 AddressOracle 作为Google地图服务的封装器处理，对于GWT的Google Maps API中的类 Geocoder 提供抽象化功能。

这是我的解决方案：

首先，我们使用Google地图实现SuggestBox的Widget建议

  public class GoogleMapsSuggestBox extends SuggestBox {
 public GoogleMapsSuggestBox（）{
 super（new AddressOracle（） ）; 
 
 
 $ / code> 

然后我们实现SuggestOracle，它包装Geocoder异步方法抽象：



  class AddressOracle扩展SuggestOracle {
 
 //需要此实例来调用getLocations-Service 
私有最终Geocoder geocoder; 
 
 
 public AddressOracle（）{
 geocoder = new Geocoder（）; 
 
 $ b @Override 
 public void requestSuggestions（final Request request，$ b $ final callback callback）{
 //这是字符串，用户有键入到目前为止
 String addressQuery = request.getQuery（）; 
 //查找建议，只有至少输入2个字母
 if（addressQuery.length（）> 2）{
 geocoder.getLocations（addressQuery，new LocationCallback（） {
 
 @Override 
 public void onFailure（int statusCode）{
 // do nothing 
} 
 
 @Override 
 public void onSuccess（JsArray< Placemark> places）{
 //从
 // getLocations-Service 
 Collection< Suggestion> result = new LinkedList<建议>（）; 
 for（int i = 0; i< places.length（）; i ++）{
 String address = places.get（i）.getAddress（）; 
 AddressSuggestion newSuggestion =新的AddressSuggestion（
地址）; 
 result.add（newSuggestion）; 
} 
响应响应=新响应（结果）; 
 callback.onSuggestionsReady（request，response）; 
} 
 
}）; 
 
} else {
 Response response = new Response（
 Collections。< Suggestion> emptyList（））; 
 callback.onSuggestionsReady（request，response）; 
} 
 
} 
} 
  

是oracle建议的一个特殊类，它只是一个带有地址的字符串。

  class AddressSuggestion实现了SuggestOracle.Suggestion，可串行化{
 
 private static final long serialVersionUID = 1L; 
 
字符串地址; 
 
 public AddressSuggestion（String address）{
 this.address = address; 
} 
 
 @Override 
 public String getDisplayString（）{
 return this.address; 
} 
 
 @Override 
 public String getReplacementString（）{
 return this.address; 
 
 
 
 
 
 
 $ b现在你可以将新的小部件绑定到你的网页中通过在入口点  - 类的 onModuleLoad（）  - 方法中写入以下行：
  RootPanel.get（hm-map）.add（new GoogleMapsSuggestBox（））; 
  
 
I want to define a SuggestBox, which behaves like the search bar in Google Maps: When you begin to type, real addresses, starting with the typed letters, appear. 

I think, that I need to use the Geocoder.getLocations(String address, LocationCallback callback) method, but I have no idea how to connect this with the oracle, which is needed by the suggest box to produce its suggestions.

Can you please give me ideas how do I connect the getLocations Method with the SuggestOracle?
解决方案
I solved this by implementing a subclass of SuggestBox, which has it's own SuggestOracle. The AddressOracle deals as a Wrapper for the Google Maps Service, for which the class Geocoderin the Google Maps API for GWT offers abstractions.

So here is my solution:

First we implement the Widget for a SuggestBox with Google Maps suggestions
public class GoogleMapsSuggestBox extends SuggestBox {
    public GoogleMapsSuggestBox() {
        super(new AddressOracle());
    }
}
Then we implement the SuggestOracle, which wraps the Geocoder async method abstractions:
class AddressOracle extends SuggestOracle {

    // this instance is needed, to call the getLocations-Service
    private final Geocoder geocoder;


    public AddressOracle() {
        geocoder = new Geocoder();
    }

    @Override
    public void requestSuggestions(final Request request,
            final Callback callback) {
        // this is the string, the user has typed so far
        String addressQuery = request.getQuery();
        // look up for suggestions, only if at least 2 letters have been typed
        if (addressQuery.length() > 2) {    
            geocoder.getLocations(addressQuery, new LocationCallback() {

                @Override
                public void onFailure(int statusCode) {
                    // do nothing
                }

                @Override
                public void onSuccess(JsArray<Placemark> places) {
                    // create an oracle response from the places, found by the
                    // getLocations-Service
                    Collection<Suggestion> result = new LinkedList<Suggestion>();
                    for (int i = 0; i < places.length(); i++) {
                        String address = places.get(i).getAddress();
                        AddressSuggestion newSuggestion = new AddressSuggestion(
                                address);
                        result.add(newSuggestion);
                    }
                    Response response = new Response(result);
                    callback.onSuggestionsReady(request, response);
                }

            });

        } else {
            Response response = new Response(
                    Collections.<Suggestion> emptyList());
            callback.onSuggestionsReady(request, response);
        }

    }
}
And this is a special class for the oracle suggestions, which just represent a String with the delivered address.
class AddressSuggestion implements SuggestOracle.Suggestion, Serializable {

    private static final long serialVersionUID = 1L;

    String address;

    public AddressSuggestion(String address) {
        this.address = address;
    }

    @Override
    public String getDisplayString() {
        return this.address;
    }

    @Override
    public String getReplacementString() {
        return this.address;
    }
}
Now you can bind the new widget into your web page by writing the following line in the onModuleLoad()-method of your EntryPoint-class:
RootPanel.get("hm-map").add(new GoogleMapsSuggestBox());


                        
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