如何使用REST Web服務解決POST上的android.os.NetworkOnMainThreadException？

Question

我在測試時看到我的數據是否會存儲在REST Web服務數據庫中一直在收到此異常。

W/System.err: android.os.NetworkOnMainThreadException 
    W/System.err:  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1303) 
    W/System.err:  at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:333) 
    W/System.err:  at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:196) 
    W/System.err:  at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178) 
    W/System.err:  at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:356) 
    W/System.err:  at java.net.Socket.connect(Socket.java:586) 
    W/System.err:  at com.android.okhttp.internal.Platform.connectSocket(Platform.java:113) 
    W/System.err:  at com.android.okhttp.Connection.connectSocket(Connection.java:196) 
    W/System.err:  at com.android.okhttp.Connection.connect(Connection.java:172) 
    W/System.err:  at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:367) 
    W/System.err:  at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:130) 
    W/System.err:  at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:329) 
    W/System.err:  at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:246) 
    W/System.err:  at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:457) 
    W/System.err:  at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:126) 
    W/System.err:  at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:257) 
    W/System.err:  at uk.ac.salford.advanceprog.eathere.MainActivity$HttpTask.doInBackground(MainActivity.java:65) 
    W/System.err:  at uk.ac.salford.advanceprog.eathere.MainActivity$1.onClick(MainActivity.java:33) 
    W/System.err:  at android.view.View.performClick(View.java:5610) 
    W/System.err:  at android.view.View$PerformClick.run(View.java:22265) 
    W/System.err:  at android.os.Handler.handleCallback(Handler.java:751) 
    W/System.err:  at android.os.Handler.dispatchMessage(Handler.java:95) 
    W/System.err:  at android.os.Looper.loop(Looper.java:154) 
    W/System.err:  at android.app.ActivityThread.main(ActivityThread.java:6077) 
    W/System.err:  at java.lang.reflect.Method.invoke(Native Method) 
    W/System.err:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
    W/System.err:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

MainActivity.java

package ...; 

import android.os.AsyncTask; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 

import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.DataOutputStream; 
import java.io.IOException; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.ProtocolException; 
import java.net.URL; 

import javax.xml.parsers.SAXParser; 
import javax.xml.parsers.SAXParserFactory; 

public class MainActivity extends AppCompatActivity { 
    Button btn; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     btn = (Button) findViewById(R.id.btn1); 

     btn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       HttpTask asnyc = new HttpTask(); 
       asnyc.doInBackground(); 
      } 
     }); 


    } 

    class HttpTask extends AsyncTask<String, String, String> { 
     @Override 
     protected void onPostExecute(String s) { 
      super.onPostExecute(s); 

     } 

     @Override 
     protected String doInBackground(String... params) { 

      URL url = null; 
      try { 
       url = new URL("http://127.0.0.1:8080/v1/users"); 
       HttpURLConnection connection = null; 
       JSONObject data = new JSONObject(); 

       data.put("email", "work@gmail.com"); 

       connection = (HttpURLConnection) url.openConnection(); 
       connection.setRequestMethod("POST"); 
       connection.setDoInput(true); 
       connection.setDoOutput(true); 
       connection.setRequestProperty("Content-Type", "application/json"); 

       if (data != null) { 
        DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream()); 
        outputStream.writeBytes(data.toString()); 
        outputStream.flush(); 
        outputStream.close(); 
       } 

       int responseCode = connection.getResponseCode(); 

      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } catch(Exception e){ 
       e.printStackTrace(); 
      } 
      return null; 
     } 
    } 

} 

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="uk.ac.salford.advanceprog.eathere.MainActivity"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Hello World!" /> 

    <Button 
     android:text="Button" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentBottom="true" 
     android:layout_centerHorizontal="true" 
     android:layout_marginBottom="78dp" 
     android:id="@+id/btn1" /> 
</RelativeLayout> 

請注意：我已經包括<uses-permission android:name="android.permission.INTERNET"/>在我的AndroidManifest.xml文件。

謝謝。

Answer 1

更換你的onClick（）方法的代碼從

HttpTask asnyc = new HttpTask(); 
asnyc.doInBackground(); 

到

HttpTask asnyc = new HttpTask(); 
asnyc.execute();