flutter 一个登录页

import 'package:flutter/material.dart';
class FormTestRoute extends StatefulWidget {
  @override
  _FormTestRouteState createState() => new _FormTestRouteState();
}
class _FormTestRouteState extends State<FormTestRoute> {
  TextEditingController _unameController = new TextEditingController();
  TextEditingController _pwdController = new TextEditingController();
  GlobalKey _formKey = new GlobalKey<FormState>();
  var obscureBoolPwd = true;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.symmetric(vertical: 32.0, horizontal: 24.0),
        child: Form(
          key: _formKey, //设置globalKey，用于后面获取FormState
          autovalidate: false, //开启自动校验
          child: Column(
            children: <Widget>[
              TextFormField(
                  autofocus: false,
                  controller: _unameController,
                  decoration: InputDecoration(
                      labelText: "用户名",
                      hintText: "用户名或邮箱",
                      icon: Icon(Icons.person)),
                  // 校验用户名
                  validator: (v) {
                    return v.trim().length > 0 ? null : "用户名不能为空";
                  }),
              TextFormField(
                  controller: _pwdController,
                  decoration: InputDecoration(
                      labelText: "密码",
                      hintText: "您的登录密码",
                      icon: Icon(Icons.lock),
                      suffixIcon: IconButton(
                        icon: Icon(
                          obscureBoolPwd
                              ? Icons.visibility_off
                              : Icons.visibility,
                        ),
                        onPressed: () {
                          //更新状态控制密码显示或隐藏
                          setState(() {
                            obscureBoolPwd = !obscureBoolPwd;
                          });
                        },
                      )),
                  obscureText: obscureBoolPwd,
                  //校验密码
                  validator: (v) {
                    return v.trim().length > 5 ? null : "密码不能少于6位";
                  }),
              // 登录按钮
              Padding(
                padding: const EdgeInsets.only(top: 28.0),
                child: Row(
                  children: <Widget>[
                    Expanded(
                      child: RaisedButton(
                        padding: EdgeInsets.all(15.0),
                        child: Text("登录"),
                        color: Theme.of(context).primaryColor,
                        textColor: Colors.white,
                        onPressed: () {
                          if ((_formKey.currentState as FormState).validate()) {
                            //验证通过提交数据
                          }
                        },
                      ),
                    ),
                  ],
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}