我正在构建一个Android应用程序，它将GPS坐标发送到服务器，但它显示gps坐标，之后立即崩溃，而不是将坐标发送到服务器。
我的MainActivity.java是
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import android.R.string;
import android.app.Activity;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements LocationListener{
private TextView latituteField;
private TextView longitudeField;
private LocationManager locationManager;
private String provider;
String lat;
String lng;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
latituteField = (TextView) findViewById(R.id.TextView02);
longitudeField = (TextView) findViewById(R.id.TextView04);
// Get the location manager
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// Define the criteria how to select the locatioin provider -> use
// default
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
// Initialize the location fields
if (location != null) {
System.out.println("Provider " + provider + " has been selected.");
onLocationChanged(location);
} else {
latituteField.setText("Location not available");
longitudeField.setText("Location not available");
}
}
/* Request updates at startup */
@Override
protected void onResume() {
super.onResume();
locationManager.requestLocationUpdates(provider, 400, 1, this);
}
/* Remove the locationlistener updates when Activity is paused */
@Override
protected void onPause() {
super.onPause();
locationManager.removeUpdates(this);
}
@Override
public void onLocationChanged(Location location) {
lat = Double.toString(location.getLatitude());
lng = Double.toString (location.getLongitude());
latituteField.setText(String.valueOf(lat));
longitudeField.setText(String.valueOf(lng));
longitudeField.setText(String.valueOf(lng));
LoadServerASYNC task = new LoadServerASYNC();
task.execute();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
Toast.makeText(this, "Enabled new provider " + provider,
Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(this, "Disabled provider " + provider,
Toast.LENGTH_SHORT).show();
}
private class LoadServerASYNC extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... arg0) {
postData(lat,lng);
StringBuilder builder = new StringBuilder();
HttpClient client = new DefaultHttpClient();
return null;
}
public void postData(String currLat, String currLon) {
// List with arameters and their values
String Text2 = "String is: " +
"Latitud = " + currLat +
"Longitud = " + currLon;
Toast.makeText(getApplicationContext(), Text2, Toast.LENGTH_LONG).show();
HttpPost post = new HttpPost("http://www.url.com/*.php");
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("myusername", currLat));
nameValuePairs.add(new BasicNameValuePair("mypassword", currLon));
HttpClient client = new DefaultHttpClient();
try {
post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = client.execute(post);
HttpEntity entity = response.getEntity();
String responseText = EntityUtils.toString(entity);
responseText = responseText.trim();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
这是我的logcat
01-21 06:16:17.400: I/System.out(1107): Provider gps has been selected.
01-21 06:16:17.630: D/gralloc_goldfish(1107): Emulator without GPU emulation detected.
01-21 06:16:17.790: W/dalvikvm(1107): threadid=11: thread exiting with uncaught exception (group=0xb4a15ba8)
01-21 06:16:17.820: E/AndroidRuntime(1107): FATAL EXCEPTION: AsyncTask #1
01-21 06:16:17.820: E/AndroidRuntime(1107): Process: com.example.gpsexample2a, PID: 1107
01-21 06:16:17.820: E/AndroidRuntime(1107): java.lang.RuntimeException: An error occured while executing doInBackground()
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.os.AsyncTask$3.done(AsyncTask.java:300)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.FutureTask.run(FutureTask.java:242)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.lang.Thread.run(Thread.java:841)
01-21 06:16:17.820: E/AndroidRuntime(1107): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.os.Handler.<init>(Handler.java:200)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.os.Handler.<init>(Handler.java:114)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.widget.Toast$TN.<init>(Toast.java:327)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.widget.Toast.<init>(Toast.java:92)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.widget.Toast.makeText(Toast.java:241)
01-21 06:16:17.820: E/AndroidRuntime(1107): at com.example.gpsexample2a.MainActivity$LoadServerASYNC.postData(MainActivity.java:143)
01-21 06:16:17.820: E/AndroidRuntime(1107): at com.example.gpsexample2a.MainActivity$LoadServerASYNC.doInBackground(MainActivity.java:128)
01-21 06:16:17.820: E/AndroidRuntime(1107): at com.example.gpsexample2a.MainActivity$LoadServerASYNC.doInBackground(MainActivity.java:1)
01-21 06:16:17.820: E/AndroidRuntime(1107): at android.os.AsyncTask$2.call(AsyncTask.java:288)
01-21 06:16:17.820: E/AndroidRuntime(1107): at java.util.concurrent.FutureTask.run(FutureTask.java:237)
答案 0 :(得分：2)
从postData方法中删除此行
Toast.makeText(getApplicationContext(), Text2, Toast.LENGTH_LONG).show();
您无法在doInBackground(String... arg0)
或使用Handler
答案 1 :(得分：1)
你应该使用
runOnUiThread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(),data, Toast.LENGTH_LONG).show();
}
});
答案 2 :(得分：1)
Toast.makeText(getApplicationContext(), Text2, Toast.LENGTH_LONG).show();
是原因。你不应该在AsyncTask类“doInBackground（）”方法上执行UI-Task。 但你可以从其他方法显示Toast，如“onPreExecute（）”，“onProgressUpdate（）”，“onPostExecute（）”方法。要知道，如何正确使用AyncTask类参考this link
答案 3 :(得分：0)
问题在于这行代码：
Toast.makeText(getApplicationContext(), Text2, Toast.LENGTH_LONG).show();
此代码与UI比赛相关，Android想要在本次比赛中运行，而不是在后台线程中运行。
因此有这个日志：
异常：无法在未调用Looper.prepare（）
的线程内创建处理程序