四种常用按钮：普通/文字/外框/悬浮/图标

ElevatedButton(onPressed: () {}, child: const Text(Elevated Button)),
const SizedBox(height: 10),
TextButton(onPressed: () {}, child: const Text(Text Button)),
const SizedBox(height: 10),
OutlinedButton(onPressed: () {}, child: const Text(Outlined Button)),
const SizedBox(height: 10),
FloatingActionButton(onPressed: () {}, child: const Icon(Icons.add)),
const SizedBox(height: 10),
IconButton(onPressed: () {}, icon: const Icon(Icons.add)),

效果：

用Material布局自带的悬浮按钮，实现右下角悬浮按钮等：

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Floating Button Example'),
        ),
        body: const YourContentWidget(),
        floatingActionButton: const MyFloatingActionButton(),
        floatingActionButtonLocation: FloatingActionButtonLocation.endDocked,
      ),
    );
  }
}

class YourContentWidget extends StatelessWidget {
  const YourContentWidget({super.key});

  @override
  Widget build(BuildContext context) {
    // Your main content goes here
    return const Center(
      child: Text('Your Content Here'),
    );
  }
}

class MyFloatingActionButton extends StatelessWidget {
  const MyFloatingActionButton({super.key});

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 16),
      child: FloatingActionButton(
        onPressed: () {
          // Add your onPressed code here!
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}

效果：