edittext焦点不允许我执行onKeyBack

import android.content.Context;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.widget.EditText;

public class CustomEditText extends EditText {

    public CustomEditText(Context context) {
        super(context);
    }

    public CustomEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (event.getKeyCode() == KeyEvent.KEYCODE_BACK && hasFocus()) {
            return true;
        }
        return super.dispatchKeyEvent(event);
    }
}

<com.example.CustomEditText
    android:id="@+id/editText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />