Question

我一直致力于获取GPS位置我已经通过了很多例子和文章，但还没有取得任何成功。可能是我错过了一些非常小的东西我想但是我是BB开发的新手。

以下是代码

package mypackage;

import javax.microedition.location.Criteria;
import javax.microedition.location.Location;
import javax.microedition.location.LocationException;
import javax.microedition.location.LocationProvider;

import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.container.MainScreen;

/**
* A class extending the MainScreen class, which provides default standard
* behavior for BlackBerry GUI applications.
*/
public final class MyScreen extends MainScreen {

/**
* Creates a new MyScreen object
*/
public MyScreen() {
    setTitle("GPS Demo");
    new GpsThread().start();
}

public boolean onClose() {
    UiApplication.getUiApplication().requestBackground();
    return false;
}

private class GpsThread extends Thread {

    Location currentLoc; // Stores component information of our position

    Criteria cr; // Settings for the GPS - we can read it at
    // different accuracy levels

    LocationProvider lp; // LocationProvider does the actual work of reading
    // coordinates from the GPS

        public GpsThread() {
            add(new LabelField(("GPS Constructor")));
            cr = new Criteria();
        }

        public void run() {

            add(new LabelField(("run")));
            showLocationToast();

        }

        private void setCriteria() {

        // I basically set no requirements on any of the horizontal,
        // vertical,
        // or
        // power consumption requirements below.
        // The distance components are set in meters if you do want to
        // establish
        // accuracy - the less the accuracy, the
        // quicker and more likely a successful read (I believe).
        // You can also set power consumption, between low, medium, high (or
        // no
        // requirement)
        // There are also a number of other settings you can tweak such as
        // minimum
        // response time, if altitude is required,
        // speed required, etc. It all depends on the exact application
        // you're
        // writing and how specific you need the info to
       cr.setCostAllowed(true);
       cr.setHorizontalAccuracy(Criteria.NO_REQUIREMENT);
       cr.setVerticalAccuracy(Criteria.NO_REQUIREMENT);
       cr.setPreferredPowerConsumption(Criteria.POWER_USAGE_HIGH);
       add(new LabelField(("Criteria set ")));

    }

    private void getLocation() throws InterruptedException {

        setCriteria();
        try {
            add(new LabelField(("getting location")));
            // Get a new instance of the location provider using the
            // criteria we
            // established above.
           if (lp != null) {
                lp.setLocationListener(null, 0, -1, -1);
                lp.reset();
                lp = null;
            }

        add(new LabelField(("lp had something so resetting it")));
        lp = LocationProvider.getInstance(cr);
        add(new LabelField(("got locationprovider instance ... ")));

        // Now populate our location object with our current location
        // (with
       // a 60 second timeout)
       lp.setLocationListener(new MyLocationListener(), 120, -1, -1);

       currentLoc = lp.getLocation(60);

       String location = "Latitude : "
       + currentLoc.getQualifiedCoordinates().getLatitude()
       + "\n Longitude : "
       + currentLoc.getQualifiedCoordinates().getLongitude();
       add(new LabelField((location)));
       }
       // If we hit the timeout or encountered some other error, report it.
       catch (LocationException e) {
           // Dialog.alert("Error getting coordinates");
           add(new LabelField(e.getMessage()));
          return;
        }
   }

   private void showLocationToast() {

        add(new LabelField(("showing toast")));

        try {
            getLocation();
        } catch (InterruptedException e) {
            add(new LabelField(e.getMessage()));
        }

        add(new LabelField(("Got all info")));
        String location = "Latitude : "
        + currentLoc.getQualifiedCoordinates().getLatitude()
        + "\n Longitude : "
        + currentLoc.getQualifiedCoordinates().getLongitude();
        add(new LabelField("Showing toast..." + location));
    }
}
}

其他信息： class my listener只有在更新位置时必须显示的对话框。我甚至试图在不使用监听器的情况下获得单一位置

像

lp.getLocation (60);

就在我设置我的听众之前。但是这两次我只把Label放到我设置监听器的地方。我将使用Timer和TimerTask，但我可以正确使用此演示。

我使用9900进行开发，应用程序应该是4.5.0

Answer 1

我看到两件看起来不合适的事情。我不能复制你的确切测试场景，所以我不能肯定他们是问题...只是他们看起来很可疑。

线程

您正在通过后台线程（您的LabelFields）调用更新您的用户界面，添加GpsThread。我不认为这是对的。一般来说，当我有一个需要更新UI的后台线程时，我总是做这样的事情

private void addNewLabelField(final String text) {
    UiApplication.getUiApplication().invokeLater(new Runnable() {
        public void run() {
           add(new LabelField(text));
        }
    });
}

然后，您可以从任何地方拨打addNewLabelField("something");。

那就是说，如果你试图这样做，我认为你会得到一个IllegalStateException，你说你没有得到任何例外。无论如何，我认为在主（UI）线程上保持与UI相关的调用仍然是一种好习惯。

位置标准

您正在使用 NO_REQUIREMENT，NO_REQUIREMENT，允许的费用，POWER_USAGE_HIGH 作为您的位置Criteria。如果我看一下这个文件：

http://supportforums.blackberry.com/t5/Java-Development/Location-APIs-Start-to-finish/ta-p/571949

...向下滚动到名为 JSR-179 API的标准映射的表格，似乎暗示这个精确的位置标准仅支持CDMA手机。但是，according to this，9900是GSM手机。你知道吗（也许我错了，它也有CDMA模型）？

但是，如果您碰巧选择了手机不支持的Criteria，您可能无法获得位置结果。所以，我肯定会尝试另一种标准组合，这些标准列在我上面链接的文件中。

这是我最好的猜测。

没有GPS

1 个答案:

线程

位置标准