原文地址 https://www.jianshu.com/p/68090114e813

1.BaseActivity

package com.xcf.admin.couldclass.Activitys.Base;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.graphics.drawable.ColorDrawable;
import android.support.v7.app.AppCompatActivity;
import android.view.KeyEvent;
import android.widget.Toast;

import com.xcf.admin.couldclass.R;
/**
 * Created by mayiyahei on 2019/1/9.
 */
public class BaseAcitivity extends AppCompatActivity{
    private AlertDialog alertDialog;

    public void showLoadingDialog() {
        alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.getWindow().setBackgroundDrawable(new ColorDrawable());
        alertDialog.setCancelable(false);
        alertDialog.setOnKeyListener(new DialogInterface.OnKeyListener() {
            @Override
            public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_SEARCH || keyCode == KeyEvent.KEYCODE_BACK)
                    return true;
                return false;
            }
        });
        alertDialog.show();
        alertDialog.setContentView(R.layout.loading_alert);
        alertDialog.setCanceledOnTouchOutside(false);
    }
    public void dismissLoadingDialog() {
        if (null != alertDialog && alertDialog.isShowing()) {
            alertDialog.dismiss();
        }
    }
    public void linkerror(){
        Toast.makeText(BaseAcitivity.this,"网络连接失败,请稍候重试",Toast.LENGTH_SHORT).show();
    }
}

2.BaseFragment

package com.xcf.admin.couldclass.Activitys.Base;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.KeyEvent;
import android.widget.Toast;

import com.xcf.admin.couldclass.R;

import java.util.List;

/**
 * Created by mayiyahei on 2019/1/9.
 */
public class BaseFragment extends Fragment{
    private AlertDialog alertDialog;
    public void showLoadingDialog() {
        alertDialog = new AlertDialog.Builder(getActivity()).create();
        alertDialog.getWindow().setBackgroundDrawable(new ColorDrawable());
        alertDialog.setCancelable(false);
        alertDialog.setOnKeyListener(new DialogInterface.OnKeyListener() {
            @Override
            public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_SEARCH || keyCode == KeyEvent.KEYCODE_BACK)
                    return true;
                return false;
            }
        });
        alertDialog.show();
        alertDialog.setContentView(R.layout.loading_alert);
        alertDialog.setCanceledOnTouchOutside(false);
    }
    public void dismissLoadingDialog() {
        if (null != alertDialog && alertDialog.isShowing()) {
            alertDialog.dismiss();
        }
    }
    public void linkerror(){
        Toast.makeText(getContext(),"网络连接失败,请稍候重试",Toast.LENGTH_SHORT).show();
    }
}