关于键盘Fragment监听KeyEvent事件【android菜鸟踩坑记录】

在MainActivity中写接口：

/**
 * 便于fragment中实现dispatchKeyEvent
 */

public interface FragmentKeyeventListener 
{
    boolean onFragmentKeyEvent(KeyEvent event);
}

public void setFragmentKeyeventListener (FragmentKeyeventListener fragmentKeyeventListener) {
    this.fragmentKeyeventListener = fragmentKeyeventListener;

}

  @Override
    public boolean dispatchKeyEvent(KeyEvent event)
 {
        if (fragmentKeyeventListener != null) 
        {
            if(fragmentKeyeventListener.onFragmentKeyEvent(event))
             {
                return true;
            }
        }
}

Fragment实现接口：

public class KeyPadFragment extends Fragment implements MainActivity.FragmentKeyeventListener
{

 /**
     * 设置按键动作显示效果
     *
     * @param event
     * @return
     */
    @Override
    public boolean onFragmentKeyEvent(KeyEvent event) 
    {
        

    }

}

因为Fragment只是View,操作都是基于Activty，该Fragment是进行按键处理，在点击返回键的时候产生了冲突，导致奔溃，便单独对返回键做了处理：

在Fragment类中做不生效：

       @Override
    public boolean onFragmentKeyEvent(KeyEvent event)
    {
   
        int action = event.getAction();
      
        int keyCode = event.getKeyCode();
        switch (action) 
        {
           case KeyEvent.ACTION_UP:
                 if (keyCode == KeyEvent.KEYCODE_BACK)
                     {
                            return false;
                      }
                    return true;

        }
    }

在Activty中做退出键处理：

        int keyCode = event.getKeyCode();
        if (keyCode == KeyEvent.KEYCODE_BACK) 
            {
                final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
                dialogBuilder.setMessage("Will exit this Application?");
                dialogBuilder.setCancelable(false);
                dialogBuilder.setPositiveButton("Yes", (dialog,which)-> 
                {
                        finish();
                });
                dialogBuilder.setNegativeButton("No",  (dialog,which)->{ });
                dialogBuilder.show();
            }
        

再提一点不相关的，但是让我后来长了点心眼儿的-----测试阶段，系统键盘映射值不对的时候，异常报错数组下标越界，导致程序崩溃，因此在fragment的按键处做了异常抛出：

 case KeyEvent.ACTION_DOWN:
 {
    tv_KeyValue.setText("key-Down value: " + keyCode);
    if (keyCode != 0 && keyCode != KeyEvent.KEYCODE_BACK)
     {
        try {                                            
               mkActivity.findViewById(keys[keyCode])
               .setBackgroundResource(R.drawable.btn_select);
           }
        catch (ArrayIndexOutOfBoundsException|NullPointerException e)
        {
                                        
           Toast.makeText(getActivity(),getString(R.string.errorkey),Toast.LENGTH_SHORT)
            .show();
          }
     }
 }
  return true;

关于键盘处理这一块改了很久，因为后来多个fragment的按键冲突，所以前期的设想很重要！