我确实在一篇文章中了解到这一点，在3.0及更高版本中，必须使用AsyncTask来预先形成任何网络活动。知道了这一点，我使用AsyncTask来调用JSON请求，我的主要类看起来像这样：
MainPage.java
public class doTheFare extends AsyncTask<Void,Void,Void>
{
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
progress = new ProgressDialog(MainPage.this);
progress.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progress.setMessage("Processing Request ...");
progress.show();
UserFunctions users = new UserFunctions();
jObj = users.distanceGET(location.getText().toString(), destination.getText().toString());
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... arg0) {
// TODO Auto-generated method stub
try{
jArr = jObj.getJSONArray("rows");
jObj1 = jArr.getJSONObject(0);
jArr2 = jObj1.getJSONArray("elements");
jObj2 = jArr2.getJSONObject(0);
jObj3 = jObj2.getJSONObject("distance");
distance_value = jObj3.getString("text");
String value = jObj3.getString("value");
SharedPreferences getPrefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String sF = getPrefs.getString("startFare", "10");
String pM = getPrefs.getString("perKilo", "27");
startFare = Double.parseDouble(sF);
perKilo = Double.parseDouble(pM);
perMeter=perKilo/5;
int parseDistance = Integer.parseInt(value);
double fare = startFare+((parseDistance/200)*perMeter);
int roundedValue = (int)Math.round(fare);
//Fare to send
taxiFare = String.valueOf(roundedValue);
Log.i("Fare Estimate", taxiFare);
}catch(Exception e){
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
progress.dismiss();
from_split = location.getText().toString();
to_split = destination.getText().toString();
if(from_split.contains(","))
{
from_fill = from_split.split(",");
}
else
{
from_fill = from_split.split(" ");
}
if(to_split.contains(","))
{
to_fill = to_split.split(",");
}
else
{
to_fill = to_split.split(" ");
}
send_location=from_fill[0];
send_destination=to_fill[0];
send_fare = taxiFare;
send_distance = distance_value;
if(isMode.equalsIgnoreCase(""))
{
Calendar c = Calendar.getInstance();
int hours = c.get(Calendar.HOUR_OF_DAY);
if(hours<6)
isMode = "nMode";
else if(hours>=21)
isMode = "nMode";
else
isMode = "dMode";
}
Intent toResults = new Intent(MainPage.this, ResultsDisplay.class);
Bundle extras = new Bundle();
extras.putString("TO", send_location);
extras.putString("FROM", send_destination);
extras.putString("FARE", send_fare);
extras.putString("DISTANCE", send_distance);
extras.putString("GMAPFROM", from_split.toString());
extras.putString("GMAPTO", to_split.toString());
extras.putString("MODE",isMode);
toResults.putExtras(extras);
startActivity(toResults);
super.onPostExecute(result);
}
}
在Activity OnClickListener我有一个AsyncTask来调用此05-10 03:02:19.823: E/AndroidRuntime(1815): FATAL EXCEPTION: main
05-10 03:02:19.823: E/AndroidRuntime(1815): android.os.NetworkOnMainThreadException
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
05-10 03:02:19.823: E/AndroidRuntime(1815): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
05-10 03:02:19.823: E/AndroidRuntime(1815): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
05-10 03:02:19.823: E/AndroidRuntime(1815): at java.net.InetAddress.getAllByName(InetAddress.java:214)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
05-10 03:02:19.823: E/AndroidRuntime(1815): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.example.calculator_taxi_fare.functions.JSONParser.getJSONFromUrl(JSONParser.java:56)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.example.calculator_taxi_fare.functions.UserFunctions.distanceGET(UserFunctions.java:28)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.example.calculator_taxi_fare.MainPage$doTheFare.onPreExecute(MainPage.java:251)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.AsyncTask.execute(AsyncTask.java:534)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.example.calculator_taxi_fare.MainPage$6.onClick(MainPage.java:230)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.view.View.performClick(View.java:4202)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.view.View$PerformClick.run(View.java:17340)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.Handler.handleCallback(Handler.java:725)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.Handler.dispatchMessage(Handler.java:92)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.os.Looper.loop(Looper.java:137)
05-10 03:02:19.823: E/AndroidRuntime(1815): at android.app.ActivityThread.main(ActivityThread.java:5039)
05-10 03:02:19.823: E/AndroidRuntime(1815): at java.lang.reflect.Method.invokeNative(Native Method)
05-10 03:02:19.823: E/AndroidRuntime(1815): at java.lang.reflect.Method.invoke(Method.java:511)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-10 03:02:19.823: E/AndroidRuntime(1815): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-10 03:02:19.823: E/AndroidRuntime(1815): at dalvik.system.NativeStart.main(Native Method)
location.setOnItemClickListener(new OnItemClickListener()
{
，即使这样，该程序也会给我以下内容
PlacesAutocomplete我是以正确的方式实施的吗？请帮助！
我也在此应用中实施了Google 3.0 or higher，其中结果/建议确实显示但在Unexpected value from nativeGetEnabledTags: 0上无法选择能够显示@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
// TODO Auto-generated method stub
autoLocation = (Places) adapterView.getItemAtPosition(position);
location.setText(autoLocation.description);
location.clearFocus();
destination.requestFocus();
Log.d("AutoCompleteTask", location.getText().toString());
}
});
destination.setAdapter(new PlacesAutoCompleteAdapter(this, R.layout.list_item));
destination.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
// TODO Auto-generated method stub
autoDestination = (Places) adapterView.getItemAtPosition(position);
destination.setText(autoDestination.description);
destination.clearFocus();
calculate.requestFocus();
Log.d("AutoCompleteTask2", destination.getText().toString());
}
});
错误。代码如下：
location.setOnItemClickListener（new OnItemClickListener（） {
{{1}}
答案 0 :(得分：3)
看来这段代码正在从网络获取数据。 你把它放在workthread中，把它放在doinBackground（）;
上 jObj = users.distanceGET(location.getText().toString(), destination.getText().toString());
答案 1 :(得分：1)
您的distanceGET方法似乎正在进行网络操作
根据文件here
onPreExecute（），在执行任务之前在UI线程上调用。 此步骤通常用于设置任务，例如通过显示 用户界面中的进度条。
在doInBackground
答案 2 :(得分：1)
您必须在doInBackground（）方法
上设置网络操作jObj = users.distanceGET(location.getText().toString(), destination.getText().toString())
必须写入doInBackground（）
答案 3 :(得分：1)
不要在预执行中执行网络操作。在doInBackground中进行网络操作，这是正确的方法。
protected Void doInBackground(Void... arg0) {
// TODO Auto-generated method stub
UserFunctions users = new UserFunctions();
jObj = users.distanceGET(location.getText().toString(),
destination.getText().toString());
try{
jArr = jObj.getJSONArray("rows");
jObj1 = jArr.getJSONObject(0);
--------------------
--------------------
}catch(Exception e){
}
}