android-asynctask - android.os.NetworkOnMainThreadException at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java :1145)

Question

我正在开发我的第一个 Android 应用程序，并且主要基于研究内置。当我尝试登录我的用户时，我得到了 android.os.NetworkOnMainThreadException错误。我在网上读到应该使用 Async 来确保不会发生此错误，但我不知道该怎么做。

下面是我所有的代码。

我的用户登录表单事件:

    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();
            }
        }
    });



}
   }

数据库处理器

     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

Answer 1

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。在您的 onViewCreated 中使用以下代码来避免此错误，否则在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

    }
}