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android.os.NetworkOnMainThreadException在android.os.StrictMode $ AndroidBlockGuardPolicy.onNetwork（StrictMode.java:1145）发生。

android-asynctask
53
我正在开发我的第一个Android应用程序，并且大部分是基于研究构建的。当我尝试登录用户时，我遇到了 android.os.NetworkOnMainThreadException 错误。我在网上阅读到异步应该被用来确保不会发生这个错误，但我不知道如何实现。
以下是我全部的代码。
我的用户登录表单活动：
import java.util.HashMap;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.finecalc.library.DatabaseHandler;
import com.finecalc.library.UserFunctions;
 

public class UserLogin extends Activity {
   Button userlogin;
   Button back;
   Button login;
   EditText inputEmail;
   EditText inputPassword;
   TextView loginErrorMsg;
 
    // JSON Response node names
    private static String KEY_SUCCESS = "success";
    private static String KEY_ERROR = "error";
    private static String KEY_ERROR_MSG = "error_msg";
    private static String KEY_UID = "uid";
    private static String KEY_NAME = "name";
    private static String KEY_EMAIL = "email";
    private static String KEY_CREATED_AT = "created_at";
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.user_login);
 
        // Importing all assets like buttons, text fields
        inputEmail = (EditText) findViewById(R.id.inputemail);
        inputPassword = (EditText) findViewById(R.id.inputpassword);
        login = (Button) findViewById(R.id.login);
        //Button register = (Button) findViewById(R.id.register);
        back =(Button)findViewById(R.id.back);
        
        loginErrorMsg = (TextView) findViewById(R.id.login_error);
 
        // Login button Click Event
        login.setOnClickListener(new View.OnClickListener() {
 
            public void onClick(View view) {
                String email = inputEmail.getText().toString();
                String password = inputPassword.getText().toString();
                UserFunctions userFunction = new UserFunctions();
                JSONObject json = userFunction.loginUser(email, password);
 
                // check for login response
                try {
                    //if (json.getString(KEY_SUCCESS) != null) {
                    if(json != null && !(json).isNull(KEY_SUCCESS)){
                        loginErrorMsg.setText("");
                        String res = json.getString(KEY_SUCCESS);
                        if(Integer.parseInt(res) == 1){
                            // user successfully logged in
                            // Store user details in SQLite Database
                            DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                            JSONObject json_user = json.getJSONObject("user");
                             
                            // Clear all previous data in database
                            userFunction.logoutUser(getApplicationContext());
                            db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                       
                             
                            // Launch Dashboard Screen
                            Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
                             
                            // Close all views before launching Dashboard
                            dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                            startActivity(dashboard);
                             
                            // Close Login Screen
                            finish();
                            
                        }else{
                            // Error in login
                            loginErrorMsg.setText("Incorrect username/password");
                        }
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

数据库处理程序

import java.util.HashMap;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
public class DatabaseHandler extends SQLiteOpenHelper {
 
    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;
 
    // Database Name
    private static final String DATABASE_NAME = "androidlta_api";
 
    // Login table name
    private static final String TABLE_LOGIN = "login";
 
    // Login Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_EMAIL = "email";
    private static final String KEY_UID = "uid";
    private static final String KEY_CREATED_AT = "created_at";
 
    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
 
    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
                + KEY_ID + " INTEGER PRIMARY KEY,"
                + KEY_NAME + " TEXT,"
                + KEY_EMAIL + " TEXT UNIQUE,"
                + KEY_UID + " TEXT,"
                + KEY_CREATED_AT + " TEXT" + ")";
        db.execSQL(CREATE_LOGIN_TABLE);
    }
 
    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);
 
        // Create tables again
        onCreate(db);
    }
 
    /**
     * Storing user details in database
     * */
    public void addUser(String name, String email, String uid, String created_at) {
        SQLiteDatabase db = this.getWritableDatabase();
 
        ContentValues values = new ContentValues();
        values.put(KEY_NAME, name); // Name
        values.put(KEY_EMAIL, email); // Email
        values.put(KEY_UID, uid); // Email
        values.put(KEY_CREATED_AT, created_at); // Created At
 
        // Inserting Row
        db.insert(TABLE_LOGIN, null, values);
        db.close(); // Closing database connection
    }
     
    /**
     * Getting user data from database
     * */
    public HashMap<String, String> getUserDetails(){
        HashMap<String,String> user = new HashMap<String,String>();
        String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;
          
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if(cursor.getCount() > 0){
            user.put("name", cursor.getString(1));
            user.put("email", cursor.getString(2));
            user.put("uid", cursor.getString(3));
            user.put("created_at", cursor.getString(4));
        }
        cursor.close();
        db.close();
        // return user
        return user;
    }
 
    /**
     * Getting user login status
     * return true if rows are there in table
     * */
    public int getRowCount() {
        String countQuery = "SELECT  * FROM " + TABLE_LOGIN;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        int rowCount = cursor.getCount();
        db.close();
        cursor.close();
         
        // return row count
        return rowCount;
    }
     
    /**
     * Re crate database
     * Delete all tables and create them again
     * */
    public void resetTables(){
        SQLiteDatabase db = this.getWritableDatabase();
        // Delete All Rows
        db.delete(TABLE_LOGIN, null, null);
        db.close();
    }
}

用户函数

import java.util.ArrayList;
import java.util.List;
 
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;
 
import android.content.Context;
import android.util.Log;
 
public class UserFunctions {
     
    private JSONParser jsonParser;
     
    // Testing in localhost using LAMP
   
    private static String loginURL = "http://127.0.0.1/android_api/index.php";
    private static String registerURL = "http://127.0.0.1/android_api/index.php";
     
    private static String login_tag = "login";
    private static String register_tag = "register";
     
    // constructor
    public UserFunctions(){
        jsonParser = new JSONParser();
    }
     
    /**
     * function make Login Request
     * @param email
     * @param password
     * */
    public JSONObject loginUser(String email, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", login_tag));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));
        JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
        // return json
        // Log.e("JSON", json.toString());
        return json;
    }
     
    /**
     * function make Login Request
     * @param name
     * @param email
     * @param password
     * */
    public JSONObject registerUser(String name, String licencenumber, String email, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", register_tag));
        params.add(new BasicNameValuePair("name", name));
        params.add(new BasicNameValuePair("licencenumber",licencenumber));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));
         
        // getting JSON Object
        JSONObject json = jsonParser.getJSONFromUrl(registerURL, params);
        // return json
        return json;
    }
     
    /**
     * Function get Login status
     * */
    public boolean isUserLoggedIn(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        int count = db.getRowCount();
        if(count > 0){
            // user logged in
            return true;
        }
        return false;
    }
     
    /**
     * Function to logout user
     * Reset Database
     * */
    public boolean logoutUser(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        db.resetTables();
        return true;
    }
     
}

JSON解析器

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
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.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
 
import android.util.Log;
 
public class JSONParser {
 
  static InputStream is = null;
  static JSONObject jObj = null;
  static String json = "";
 
  // constructor
  public JSONParser() {
 
  }
 
  public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) {
 
        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            httpPost.setEntity(new UrlEncodedFormEntity(params));
 
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
 
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
 
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "n");
            }
            is.close();
            json = sb.toString();
           // Log.e("JSON", json);
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }
 
        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);           
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }
 
        // return JSON String
        return jObj;
 
    }
}

我的AndroidManifest还包括：
<uses-permission android:name="android.permission.INTERNET" />。

以下是我的错误：

    08-02 04:39:23.410: D/(2642): HostConnection::get() New Host Connection established 0xb97a3b90, tid 2642
    08-02 04:39:23.480: W/EGL_emulation(2642): eglSurfaceAttrib not implemented
    08-02 04:39:23.480: D/OpenGLRenderer(2642): Enabling debug mode 0
    08-02 04:39:29.150: W/EGL_emulation(2642): eglSurfaceAttrib not implemented
    08-02 04:39:33.650: D/InputEventConsistencyVerifier(2642): KeyEvent: ACTION_UP but key was not down.
    08-02 04:39:33.650: D/InputEventConsistencyVerifier(2642):   in android.widget.EditText{b1fa92d8 VFED..CL .F...... 0,82-240,118 #7f07001c app:id/inputpassword}
    08-02 04:39:33.650: D/InputEventConsistencyVerifier(2642):   0: sent at 7133734000000, KeyEvent { action=ACTION_UP, keyCode=KEYCODE_TAB, scanCode=15, metaState=0, flags=0x8, repeatCount=0, eventTime=7133734, downTime=7133655, deviceId=0, source=0x101 }
    08-02 04:39:38.231: D/dalvikvm(2642): GC_FOR_ALLOC freed 177K, 8% free 2964K/3192K, paused 21ms, total 24ms
    08-02 04:39:38.321: D/AndroidRuntime(2642): Shutting down VM
    08-02 04:39:38.321: W/dalvikvm(2642): threadid=1: thread exiting with uncaught exception (group=0xb1cd3b20)
    08-02 04:39:38.331: E/AndroidRuntime(2642): FATAL EXCEPTION: main
    08-02 04:39:38.331: E/AndroidRuntime(2642): Process: com.finecalc.ltafinecalculator, PID: 2642
    08-02 04:39:38.331: E/AndroidRuntime(2642): android.os.NetworkOnMainThreadException
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at libcore.io.IoBridge.connect(IoBridge.java:112)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at java.net.Socket.connect(Socket.java:843)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at com.finecalc.library.JSONParser.getJSONFromUrl(JSONParser.java:41)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at com.finecalc.library.UserFunctions.loginUser(UserFunctions.java:42)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at com.finecalc.ltafinecalculator.UserLogin$1.onClick(UserLogin.java:57)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.view.View.performClick(View.java:4438)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.view.View$PerformClick.run(View.java:18422)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.os.Handler.handleCallback(Handler.java:733)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.os.Handler.dispatchMessage(Handler.java:95)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.os.Looper.loop(Looper.java:136)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at android.app.ActivityThread.main(ActivityThread.java:5017)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at java.lang.reflect.Method.invokeNative(Native Method)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at java.lang.reflect.Method.invoke(Method.java:515)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
    08-02 04:39:38.331: E/AndroidRuntime(2642):     at dalvik.system.NativeStart.main(Native Method)
    08-02 04:39:41.111: D/(2670): HostConnection::get() New Host Connection established 0xb97a3cc0, tid 2670
    08-02 04:39:41.181: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:39:41.181: D/OpenGLRenderer(2670): Enabling debug mode 0
    08-02 04:39:45.771: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:39:48.371: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:39:50.971: D/dalvikvm(2670): GC_FOR_ALLOC freed 123K, 6% free 3018K/3192K, paused 28ms, total 32ms
    08-02 04:39:51.581: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:39:51.811: D/dalvikvm(2670): GC_FOR_ALLOC freed 152K, 6% free 3380K/3584K, paused 22ms, total 31ms
    08-02 04:40:18.351: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:40:21.741: W/EGL_emulation(2670): eglSurfaceAttrib not implemented
    08-02 04:40:23.021: D/AndroidRuntime(2670): Shutting down VM
    08-02 04:40:23.021: W/dalvikvm(2670): threadid=1: thread exiting with uncaught exception (group=0xb1cd3b20)
    08-02 04:40:23.031: E/AndroidRuntime(2670): FATAL EXCEPTION: main
    08-02 04:40:23.031: E/AndroidRuntime(2670): Process: com.finecalc.ltafinecalculator, PID: 2670
    08-02 04:40:23.031: E/AndroidRuntime(2670): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.finecalc.ltafinecalculator/com.finecalc.ltafinecalculator.UserRegister}: java.lang.NullPointerException
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.os.Handler.dispatchMessage(Handler.java:102)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.os.Looper.loop(Looper.java:136)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread.main(ActivityThread.java:5017)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at java.lang.reflect.Method.invokeNative(Native Method)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at java.lang.reflect.Method.invoke(Method.java:515)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at dalvik.system.NativeStart.main(Native Method)
    08-02 04:40:23.031: E/AndroidRuntime(2670): Caused by: java.lang.NullPointerException
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at com.finecalc.ltafinecalculator.UserRegister.onCreate(UserRegister.java:26)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.Activity.performCreate(Activity.java:5231)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
    08-02 04:40:23.031: E/AndroidRuntime(2670):     ... 11 more
可能是Android http连接异常的重复问题。 - Amir Ali Akbari
4个回答
112

当应用程序尝试在主线程中执行网络操作时，会抛出此异常。请在您的onViewCreated方法中使用以下代码以避免此错误，否则请在新线程或异步类中调用您的网络操作（从Web服务器获取数据）请求。

public void onViewCreated(View view, Bundle savedInstanceState) 
{
    int SDK_INT = android.os.Build.VERSION.SDK_INT;
    if (SDK_INT > 8) 
    {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
                .permitAll().build();
        StrictMode.setThreadPolicy(policy);
        //your codes here

    }
}
非常感谢。这已经解决了错误，但现在我只剩下一个错误，即：类型为 java.lang.String 的值表无法转换为 JSONObject。 - Jason6916
1
上面的代码实际上已经解决了问题，但现在我又遇到了另一个错误，这个错误让我整整一天都在苦苦挣扎。如果你能帮忙解决这个问题，我会非常感激。http://stackoverflow.com/questions/25116623/e-json-parser1506-error-parsing-data-end-of-input-at-character-0-of?noredirect=1#comment39089381_25116623 - Jason6916
谢谢。我只是不知道我卡在哪里，只有那一行错误在日志中弹出。 - Jason6916
看起来你的 PHP 文件返回了无效的响应，请调试你的 PHP 代码，确保返回的 JSON 值是格式良好的结构。 - APriya
在单独的线程中进行调用对我很有帮助 :-) - Saqib R.
在 Kotlin 中相同的代码：if (Build.VERSION.SDK_INT > 9) { val policy = StrictMode.ThreadPolicy.Builder().permitAll().build() StrictMode.setThreadPolicy(policy) } - Stefan Horning
47

尝试添加以下代码：

将此代码添加到您的用户登录活动的下方

         setContentView(R.layout.user_login);
        if (android.os.Build.VERSION.SDK_INT > 9)
        {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
        }

希望这能对您有所帮助！

正常工作 onCreate，谢谢老兄。 - Florida
5

以下代码用于 Kotlin：

minSdkVersion 14

如果你的应用级别build.gradle中的minSdkVersion小于21，则使用下面的代码。

if (Build.VERSION.SDK_INT > 9) {
      val policy = ThreadPolicy.Builder().permitAll().build()
      StrictMode.setThreadPolicy(policy)
}

minSdkVersion 为 21 或更高版本时，请使用以下代码于应用程序级别的build.gradle

val policy = ThreadPolicy.Builder().permitAll().build()
StrictMode.setThreadPolicy(policy)
2
使用 AsyncTask 在不同线程上运行长时间运行的api调用。
示例代码
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;

public class AsyncExample extends Activity{


private String url="http://www.google.co.in";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    apiCall();
}


private void apiCall() {

    new AsyncCaller().execute();

}

private class AsyncCaller extends AsyncTask<Void, Void, Void>
{
    ProgressDialog pdLoading = new ProgressDialog(AsyncExample.this);

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        //this method will be running on UI thread
        pdLoading.setMessage("\tLoading...");
        pdLoading.show();
    }
    @Override
    protected Void doInBackground(Void... params) {

        //this method will be running on background thread so don't update UI frome here
        //do your long running http tasks here,you dont want to pass argument and u can access the parent class' variable url over here


        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);

        //this method will be running on UI thread

        pdLoading.dismiss();
    }

    }
}
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