如何使用GPS即时读取位置 [英] How to make an immediate reading location using GPS
问题描述
我编写了一个 Codenameone应用程序，在某些情况下需要对位置进行测量，并且需要（在时间上）立即读取。
I wrote a "Codenameone App" that needs to make Location's measures in some situations and it needs to read immediately (at time).
要实现此目标，我正在使用Display对象中的方法 getLocationSync（long timeout = 10000）。该代码是这样的：
To accomplish this goal, I'm using method "getLocationSync(long timeout=10000)" from Display object. The code is something like that:
Location loc = LocationManager
.getLocationManager()
.getCurrentLocationSync(10000);
此方法的JavaDoc说它会立即执行测量并建议：
注意他的方法将一直阻塞直到返回结果，所以您可能要在运行时使用InfiniteProgress之类的东西。
The JavaDoc of this method says it executes a measure at moment and advises: "Notice that his method will block until a result is returned so you might want to use something like InfiniteProgress while this is running"
您可以看到，我用10调用了该方法
As you can see, I called the method with 10 seconds for timeout.
在实践中，我得到一个Location对象作为响应，但是返回的度量不是（在时间上的）立即度量。这种方法会重复一段时间（大约4或5分钟），即使我在这4分钟内改变了电话位置的时间也是如此。
Well, in practice, I get a Location object as response, but the measure returned isn't an immediate measure (at time). This method repeats the same result for a while ( about 4 or 5 minutes), even when I change the phone location significantly during those 4 minutes.
我注意到的另一件事，多数情况下，我将 InfiniteProgress称为 getCurrentLocationSync。通话很快返回。
Another thing I noticed, Most of the times I call "getCurrentLocationSync" the "InfiniteProgress" doesn't appear. The call returns quickly.
我做错了吗？
我需要怎么做才能真正获得所需的位置度量？
Am I doing something wrong? What do I need to do to get a real measure of location as I need?
推荐答案
getCurrentLocationSync 等待一个存在的位置，该位置与纯GPS模式更相关，而与现代混合位置API（如在iOS / Android中实现的位置）不相关。
The getCurrentLocationSync waits the a location to exist which is more relevant for pure GPS modes but not as relevant in modern hybrid location API's such as those implemented in iOS/Android.
默认情况下，iOS和Android都使用混合位置API，这意味着设备将结合使用wifi，手机数据和GPS来为您提供更准确，更即时的位置。即使在使用GPS的情况下，也无法知道确切的设备位置，这是有问题的，因为位置在相对较大的误差范围内，并且大多数情况下，只有在设备开始移动后才能更准确地计算出位置。
Both iOS and Android use a hybrid location API by default which means the device will use a combination of wifi, cell data and GPS to give you a location that's both more accurate and instant. It's problematic to know the exact device location even with GPS as location is within a relatively large margin of error and can mostly be calculated more accurately only once the device starts moving.
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