这里有另一个解决方案:

Container(
    height: MediaQuery.of(context).size.height * 0.10,
    width: MediaQuery.of(context).size.width,
    child: ButtonTheme(
        minWidth: MediaQuery.of(context).size.width * 0.75,
        child: RaisedButton(
            shape: RoundedRectangleBorder(
                borderRadius: new BorderRadius.circular(25.0),
                side: BorderSide(color: Colors.blue)),
                onPressed: () async {
                    // Do something
                },
                color: Colors.red[900],
                textColor: Colors.white,
                child: Padding(
                    padding: const EdgeInsets.all(8.0),
                    child: Text("Button Text,
                    style: TextStyle(fontSize: 24)),
            ),
        ),
    ),
),

试试这个:

SizedBox(
  height: 40.0,
  child: MaterialButton(
    child: Text("Button"),
    color: Colors.blue,
    disabledColor: Colors.blue,
    shape: RoundedRectangleBorder(
      borderRadius: BorderRadius.all(
        Radius.circular(10.0), // Change your border radius here
      ),
    ),
    onPressed: () {},
  ),
),

您可以简单地使用RaisedButton

Padding(
  padding: EdgeInsets.only(left: 150.0, right: 0.0),
  child: RaisedButton(
    textColor: Colors.white,
    color: Colors.black,
    child: Text("Search"),
    onPressed: () {},
    shape: new RoundedRectangleBorder(
      borderRadius: new BorderRadius.circular(30.0),
    ),
  ),
)

输出:

更多信息:RSCoder

如果你使用材质应用程序作为你的主小部件，你总是可以使用材质按钮。

Padding(
  padding: EdgeInsets.symmetric(vertical: 16.0),
  child: Material(
    borderRadius: BorderRadius.circular(30.0),//Set this up for rounding corners.
    shadowColor: Colors.lightBlueAccent.shade100,
    child: MaterialButton(
      minWidth: 200.0,
      height: 42.0,
      onPressed: (){//Actions here//},
      color: Colors.lightBlueAccent,
      child: Text('Log in', style: TextStyle(color: Colors.white),),
    ),
  ),
)

您可以使用下面的代码创建一个渐变颜色的圆形按钮。

 Container(
          width: 130.0,
          height: 43.0,
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(30.0),
            gradient: LinearGradient(
              // Where the linear gradient begins and ends
              begin: Alignment.topRight,
              end: Alignment.bottomLeft,
              // Add one stop for each color. Stops should increase from 0 to 1
              stops: [0.1, 0.9],
              colors: [
                // Colors are easy thanks to Flutter's Colors class.
                Color(0xff1d83ab),
                Color(0xff0cbab8),
              ],
            ),
          ),
          child: FlatButton(
            child: Text(
              'Sign In',
              style: TextStyle(
                fontSize: 16.0,
                fontFamily: 'Righteous',
                fontWeight: FontWeight.w600,
              ),
            ),
            textColor: Colors.white,
            color: Colors.transparent,
            shape:
                RoundedRectangleBorder(borderRadius: BorderRadius.circular(30.0)),
            onPressed: () {

            },
          ),
        );

在Null安全之后，使用ElevatedButton而不是RaisedButton，因为RaisedButton就像文档中说的那样被贬低了。

             child: ElevatedButton(
                onPressed: () {},
                child: const Text('Add item to the list'),
                style: ButtonStyle(
                  backgroundColor:
                      MaterialStateProperty.all<Color>(Common.buttonColor),
                  shape: MaterialStateProperty.all<RoundedRectangleBorder>(
                    RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(18.0),
                    ),
                  ),
                ),
              ),