我正在从 OutputStreamWriter() 中获取 android.os.NetworkOnMainThreadException 和另一个未知异常

Question

我收到NetworkOnMainThreadException的异常和OutputStreamWriter((的未知异常。这个类负责通过PHP脚本连接到SQL数据库http://213.251.43.215/addContact.php如果匹配，它将从数据库返回值。它似乎没有成功连接。

包com.example.a_phi.nowswap；

import android.os.AsyncTask;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
public class EstablishConnection extends AsyncTask<String, Void, String>{
StringBuilder sb = new StringBuilder();
public String doInBackground(String... id) {
String link = "http://213.251.43.215/addContact.php";
try {
URL url = new URL(link);
String data = URLEncoder.encode("id", "UTF-8")
+ "=" + URLEncoder.encode(id[0], "UTF-8");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
BufferedReader reader = new BufferedReader(new
InputStreamReader(conn.getInputStream()));
String line;
// Read Server Response
while((line = reader.readLine()) != null) {
sb.append(line);
break;
}
}catch(MalformedURLException e) {
System.out.print("MalformedURLException" + e.getMessage());
e.printStackTrace();
}
catch(IOException e){
System.out.print("IOException"+e.getMessage());
e.printStackTrace();
}
return sb.toString();
}
}

飞行员班。。。

包com.example.a_phi.nowswap；

import android.annotation.TargetApi;
import android.content.pm.PackageManager;
import android.nfc.NfcAdapter;
import android.nfc.tech.IsoDep;
import android.os.Build;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.nfc.Tag;
import android.content.Intent;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;
public class Pilot extends AppCompatActivity {
private String mParentPath;
// Incoming Intent
private Intent mIntent;
public Timer timer1 = new Timer();
NfcAdapter nfcadapter;
public String idReceived;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pilot);
View buttonPersonal = findViewById(R.id.buttonPersonal);
View buttonProfessional = findViewById(R.id.buttonProfessional);
View buttonUserGuide = findViewById(R.id.userGuide);
//phone is put into reader mode to prevent android beam interfering
enableReaderMode();
//executes createContact() method periodically every second to refresh
getData accessGetData = new getData();
timer1.schedule(new TimerTask() {
@Override
public void run() {
createContact();
}
}, 500, 500);


PackageManager pm = this.getPackageManager();
if(!pm.hasSystemFeature(PackageManager.FEATURE_NFC)) {
Toast.makeText(this, "The device does not have NFC hardware.",
Toast.LENGTH_SHORT).show();
} else if(Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
Toast.makeText(this, "Android Beam is not supported.",
Toast.LENGTH_SHORT).show();
}
buttonPersonal.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
Intent loadPersonal = new Intent(Pilot.this, personalHome.class);
startActivity(loadPersonal);
}
});
buttonProfessional.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
Intent loadProfessional = new Intent(Pilot.this, professionalHome.class);
startActivity(loadProfessional);
}
});

}

private byte[] selectApdu(byte[] aid) {
byte[] commandApdu = new byte[6 + aid.length];
commandApdu[0] = (byte)0x00; //CLA
commandApdu[1] = (byte)0xA4; //INS
commandApdu[2] = (byte)0x04; //P1
commandApdu[3] = (byte)0x00; //P2
commandApdu[4] = (byte)(aid.length & 0xFF); //Lc
System.arraycopy(aid, 0, commandApdu, 5, aid.length); //DATA
commandApdu[commandApdu.length - 1] = (byte)0x00; //Le
return commandApdu;
}

/**enableReaderMode essentially turns off services such as Android Beam and ensures the device only READS nfc tags
* allowing a smoother user interaction
*/
@TargetApi(19)
private void enableReaderMode() {
nfcadapter = NfcAdapter.getDefaultAdapter(this);
Bundle options = new Bundle();
options.putInt(NfcAdapter.EXTRA_READER_PRESENCE_CHECK_DELAY, 5000);
nfcadapter.enableReaderMode(this, new NfcAdapter.ReaderCallback() {
@Override
public void onTagDiscovered(Tag tag) {
System.out.println("NFC onTagDiscovered " + tag.toString());
IsoDep isoDep = IsoDep.get(tag);
if (isoDep != null) {
try {
isoDep.connect();
//SelectAID command is sent to phone with HCE
byte[] result = isoDep.transceive(selectApdu(SelectAID));
idReceived = new String(result, "US-ASCII");
System.out.println("s outputs this "+ idReceived.substring(0,10));
idReceived = idReceived.substring(0,10);
checkProfile();
isoDep.close();
EstablishConnection accessEC = new EstablishConnection();
System.out.println("hello");
System.out.println("Dataset is "+accessEC.doInBackground(idReceived));
} catch(IOException e) {
e.printStackTrace();
} finally {
try {
isoDep.close();
} catch(Exception ignored) {}
}
}
}
}, NfcAdapter.FLAG_READER_NFC_A | NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK,
options);
}
public String getIdReceived(){
return idReceived;
}
public void checkProfile(){
getData accessGetData = new getData();
//   System.out.println("hashlist value is "+accessGetData.doInBackground());
}

public static byte[] SelectAID = new byte[]{ (byte) 0xF2, (byte) 0x39, (byte) 0x85, (byte) 0x63,
(byte) 0x24, (byte) 0x89, (byte) 0x73};
public void createContact() {
File newContact = new File("/storage/emulated/0/beam/", "personalInfoC.txt");
/**there is a glitch on android beam with the file naming - sometimes it calls the file professionalInfoC.txt
and other times professionalInfoC-0.txt **/
if(!newContact.exists()) {
newContact = new File("/storage/emulated/0/beam", "personalInfoC-0.txt");
if(!newContact.exists()){
File newContactProf = new File("/storage/emulated/0/beam", "professionalInfoC.txt");
if(newContactProf.exists()){
//new activity will only be loaded if the file exists
Intent loadNewContact = new Intent(Pilot.this, receivedContact.class);
finish();
timer1.cancel();
startActivityForResult(loadNewContact, 1);
}
else if(!newContactProf.exists()){
newContactProf = new File("/storage/emulated/0/beam", "professionalInfoC-0.txt");
if(newContactProf.exists()) {
Intent loadNewContact = new Intent(Pilot.this, receivedContact.class);
finish();
timer1.cancel();
startActivityForResult(loadNewContact, 1);
}
}
}
}
};


}

这是堆栈跟踪

07-19 00:53:14.436 13679-13692/com.example.a_phi.nowswap W/System.err: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1315)
07-19 00:53:14.437 13679-13692/com.example.a_phi.nowswap W/System.err:     at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:333)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:196)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:356)
at java.net.Socket.connect(Socket.java:592)
at com.android.okhttp.internal.Platform.connectSocket(Platform.java:113)
at com.android.okhttp.Connection.connectSocket(Connection.java:196)
at com.android.okhttp.Connection.connect(Connection.java:172)
at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:367)
at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:130)
at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:329)
at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:246)
at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:457)
at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:126)
at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:257)
at com.example.a_phi.nowswap.EstablishConnection.doInBackground(EstablishConnection.java:29)
at com.example.a_phi.nowswap.Pilot$4.onTagDiscovered(Pilot.java:121)
at android.nfc.NfcActivityManager.onTagDiscovered(NfcActivityManager.java:450)
at android.nfc.IAppCallback$Stub.onTransact(IAppCallback.java:83)
at android.os.Binder.execTransact(Binder.java:565)

如何解决此问题？任何帮助都将不胜感激。

Answer 1

在enableReaderMode((方法中对AsyncTask的对象调用excute方法。

EstablishConnection accessEC = new EstablishConnection();
System.out.println("hello");
System.out.println("Dataset is "+accessEC.execute(idReceived));

您直接调用accessEC.donInBackground(idReceived(，它在当前(Main(线程中运行该方法。