我在Android应用中有一个应执行URL的方法。但是我总是得到NetworkOnMainThreadException,因为不允许在主线程上运行它。在网上,我发现了许多解决此问题的方法。不幸的是,我对Java还是很陌生,对此了解也不多。
该应用程序具有一个按钮,当按下该按钮时将执行URL。
package com.softpi.raspbicontroll;
import java.io.BufferedInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class MainActivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
setContentView(R.layout.activity_main);
}
public void doYellow(View view) {
HttpURLConnection urlConnection = null;
try {
URL url = new URL("http://raspberrypi/yellow.php");
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
}
catch (Exception e) {
System.out.println("Shit!");
e.printStackTrace();
} finally {
assert urlConnection != null;
urlConnection.disconnect();
}
}
private static void readStream(InputStream in) {}
}
<Button
...
android:onClick="doYellow"
...
app:layout_constraintTop_toTopOf="parent" />
有人可以帮我找到适合初学者的解决方案吗?
而不是在主线程中运行网络调用,只需使用AsyncTask。还有一个更好的解决方案是使用Retrofit,但是对于初学者来说并不是那么简单
private class AsyncTaskRunner extends AsyncTask<String, String, String> {
private String resp;
ProgressDialog progressDialog;
@Override
protected String doInBackground(String... params) {
HttpURLConnection urlConnection = null;
try {
URL url = new URL("http://raspberrypi/yellow.php");
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
}
catch (Exception e) {
System.out.println("Shit!");
e.printStackTrace();
} finally {
assert urlConnection != null;
urlConnection.disconnect();
}
return null;
}
@Override
protected void onPostExecute(String result) {
// execution of result of Long time consuming operation
progressDialog.dismiss();
finalResult.setText(result);
}
@Override
protected void onPreExecute() {
progressDialog = ProgressDialog.show(MainActivity.this,
"ProgressDialog",
"Wait for "+time.getText().toString()+ " seconds");
}
@Override
protected void onProgressUpdate(String... text) {
finalResult.setText(text[0]);
}
}
[doYellow
函数将是:
public void doYellow(View view) {
new AsyncTaskRunner().execute("http://stackoverflow.com");
}
N.B。 :我没有运行代码,因此,它可能/可能不需要做一些修改