1.创建一个layout

dialog_loadding.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center">

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:gravity="center"
        android:background="@null">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_marginBottom="0dp"
            android:gravity="center|bottom"
            android:orientation="vertical">

            <ProgressBar
                style="@android:style/Widget.ProgressBar"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:indeterminateDrawable="@drawable/shape_progress_bar" />


            <TextView
                android:id="@+id/tv_text"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="16dp"
                android:layout_marginBottom="16dp"
                android:text="正在加载"
                android:textColor="#fff" />
        </LinearLayout>

    </RelativeLayout>

</RelativeLayout>

2创建LoadingDialog

package com.companyname.view;

import android.app.Dialog;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.support.annotation.NonNull;
import android.view.MotionEvent;
import android.widget.TextView;

import com.companyname.R;

public class LoadingDialog extends Dialog {

    private TextView tv_text;

    public LoadingDialog(Context context) {
        super(context);
        //设置对话框背景透明
        if (getWindow()!= null) {
            getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
            setContentView(R.layout.dialog_loadding);
            tv_text = findViewById(R.id.tv_text);
            setCanceledOnTouchOutside(false);
        }
    }

    /**
     * 为加载进度个对话框设置不同的提示消息
     *
     * @param message 给用户展示的提示信息
     * @return build模式设计，可以链式调用
     */
    public LoadingDialog setMessage(String message) {
        tv_text.setText(message);
        return this;
    }

    @Override
    public boolean onTouchEvent(@NonNull MotionEvent event) {
        return true;
    }

    @Override
    public void onBackPressed() {

    }
}

在代码中使用

    private void initDialog() {
        if (loadingDialog == null) {
            loadingDialog = new LoadingDialog(mContext);
        }
    }

    private void showDialog() {
        if (loadingDialog == null) {
            initDialog();
        }

        if (loadingDialog.isShowing()) {
            loadingDialog.hide();
        }

        loadingDialog.show();

    }

    private void hideDialog() {
        if (loadingDialog == null) {
            initDialog();
        }

        if (loadingDialog.isShowing()) {
            loadingDialog.hide();
        }
    }