Android程序多次打开QR扫描仪

Question

I am having an application where on Login screen, i have QR scanner button. When user clicks the button, the QR scanner app opens and after scanning, it toasts the message to user.

At present, on button click, the QR scanner opens and is able to capture the data from QR code, but it reopens again. Here is the pattern of execution:

1. QR scanner opens. reads the QR code (as expected)
<after this point everything is wrong>
2. QR scanner opens again.
3. My main_screen comes back
4. QR scanner opens again and i read QR code.
5. My main screen comes back

Can someone please help: Here are my files:

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.amandeepsingh.loyaltyapp2" >

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".SplashScreenActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
<activity android:name=".MainActivity" >
</activity>
    <activity
        android:name=".Login"
        android:label="@string/title_activity_login" >
    </activity>
    <activity
        android:name=".Register"
        android:label="@string/title_activity_register" >
    </activity>
    <!--added for QR codes scanner-->
    <activity android:name=".AndroidBarcodeQrExample"/>
    <!-- QR code ends here-->
</application>

</manifest>

This is my layout file:

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dp"
android:background="@drawable/androidrain"
tools:context="com.example.amandeepsingh.loyaltyapp2.Login">

<TextView
    android:layout_width="wrap_content"
    android:text="Email"
    android:textColor="#FFFFFF"
    android:layout_height="wrap_content" />

<EditText
    android:id="@+id/etEmail"
    android:layout_width="match_parent"
    android:layout_marginBottom="10dp"
    android:textColor="#FFFFFF"
    android:layout_height="wrap_content" />

<TextView
    android:layout_width="wrap_content"
    android:text="Phone Number"
    android:textColor="#FFFFFF"
    android:layout_height="wrap_content" />

<EditText
    android:id="@+id/etPhoneNumber"
    android:layout_width="match_parent"
    android:layout_marginBottom="10dp"
    android:textColor="#FFFFFF"
    android:layout_height="wrap_content" />


<Button
    android:id="@+id/bLogOut"
    android:text="LogOut"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

<Button
    android:id="@+id/bEarnPoints"
    android:layout_width="250dp"
    android:layout_height="80dp"
    android:layout_gravity="center"
    android:layout_margin="10dp"
    android:gravity="center"

    android:text="Earn Points"
    android:textSize="18dp" >
</Button>

<Button
    android:id="@+id/bRedeamPoints"
    android:layout_width="250dp"
    android:layout_height="80dp"
    android:layout_gravity="center"
    android:layout_margin="10dp"
    android:gravity="center"

    android:text="Redeam Points"
    android:textSize="18dp" >
</Button>

</LinearLayout>

This is the code from where i have put QR code scanner button:

MainActivity.java

public class MainActivity extends Activity implements View.OnClickListener{

Button bLogOut;
EditText etEmail,etPhoneNumber;
//this is for having access to userlocalstore to save/remove local data to user phone during log inor Log out. So that if logout is pressed
//the data is wiped off the local storage on user mobile
UserLocalStore userLocalStore;

//added for QR codes scanner
Button bEarnPoints,bRedeamPoints;
//QR code scanner ends

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

    etEmail= (EditText)findViewById(R.id.etEmail);
    etPhoneNumber =(EditText)findViewById(R.id.etPhoneNumber);
    bLogOut = (Button)findViewById(R.id.bLogOut);

    bLogOut.setOnClickListener(this);

    userLocalStore = new UserLocalStore(this);
    //added for QR codes scanner
    bEarnPoints=(Button)findViewById(R.id.bEarnPoints);
    bRedeamPoints=(Button)findViewById(R.id.bRedeamPoints);
    bEarnPoints.setOnClickListener(this);
    bRedeamPoints.setOnClickListener(this);
    //QR code ends here
}

@Override
public void onClick(View v) {
    switch(v.getId()){
        case R.id.bLogOut:
            userLocalStore.clearUserData();
            userLocalStore.setUserLoggedIn(false);

            startActivity(new Intent(this,Login.class));

            break;

        //added for QR codes scanner
        case R.id.bEarnPoints:
            startActivity(new Intent(this,AndroidBarcodeQrExample.class));
            break;

        case R.id.bRedeamPoints:
            startActivity(new Intent(this,AndroidBarcodeQrExample.class));
            break;

        //QR ends here
    }

}

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

    if (authenticate() == true) {
        displayUserDetails();
    }
}

public boolean authenticate(){
    return userLocalStore.getUserLoggedIn();
}

public void displayUserDetails(){
    User user = userLocalStore.getLoggedInUser();
    etEmail.setText(user.Email);
    etPhoneNumber.setText(user.PhoneNumber+"");

}

//code below this is not being used
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

and this is the QRScanner code:

AndroidBarcodeQrExample.java

public class AndroidBarcodeQrExample extends Activity {
/** Called when the activity is first created. */

static final String ACTION_SCAN = "com.google.zxing.client.android.SCAN";

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

public void scanBar(View v) {
    try {
        Intent intent = new Intent(ACTION_SCAN);
        intent.putExtra("SCAN_MODE", "PRODUCT_MODE");
        startActivityForResult(intent, 0);
    } catch (ActivityNotFoundException anfe) {
        showDialog(AndroidBarcodeQrExample.this, "No Scanner Found", "Download a scanner code activity?", "Yes", "No").show();
    }
}

public void scanQR() {
    try {
        Intent intent = new Intent(ACTION_SCAN);
        intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
        startActivityForResult(intent, 0);
    } catch (ActivityNotFoundException anfe) {
        showDialog(AndroidBarcodeQrExample.this, "No Scanner Found", "Download a scanner code activity?", "Yes", "No").show();
    }
}

private static AlertDialog showDialog(final Activity act, CharSequence title, CharSequence message, CharSequence buttonYes, CharSequence buttonNo) {
    AlertDialog.Builder downloadDialog = new AlertDialog.Builder(act);
    downloadDialog.setTitle(title);
    downloadDialog.setMessage(message);
    downloadDialog.setPositiveButton(buttonYes, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialogInterface, int i) {
            Uri uri = Uri.parse("market://search?q=pname:" + "com.google.zxing.client.android");
            Intent intent = new Intent(Intent.ACTION_VIEW, uri);
            try {
                act.startActivity(intent);
            } catch (ActivityNotFoundException anfe) {

            }
        }
    });
    downloadDialog.setNegativeButton(buttonNo, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialogInterface, int i) {
        }
    });
    return downloadDialog.show();
}

public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    if (requestCode == 0) {
        if (resultCode == RESULT_OK) {
            String contents = intent.getStringExtra("SCAN_RESULT");
            String format = intent.getStringExtra("SCAN_RESULT_FORMAT");

            Toast toast = Toast.makeText(this, "Content:" + contents + " Format:" + format, Toast.LENGTH_LONG);
            toast.show();
        }
    }
}
}

Please help with the multiple unnecessary QR scanner opening issue.

Thanks in advance!

Answer 1

In AndroidBarcodeQrExample Oncreate you are launching an intent without any condition.

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        scanQR();  // here everytime it starts an activity again and again.
    }

Based on some condition you have to launch an intent.