React-Native-Expo:登录时，setState

import React, { Component } from 'react';
import { View, TextInput, Button, Text } from 'react-native';

class LoginPage extends Component {
  constructor(props) {
    super(props);
    this.state = {
      username: '',
      password: ''
    };
  }

  handleUsernameChange = (text) => {
    this.setState({ username: text });
  }

  handlePasswordChange = (text) => {
    this.setState({ password: text });
  }

  handleLogin = () => {
    // 在这里处理登录逻辑，可以使用this.state中保存的用户名和密码
  }

  render() {
    return (
      <View>
        <TextInput
          placeholder="用户名"
          onChangeText={this.handleUsernameChange}
        />
        <TextInput
          placeholder="密码"
          onChangeText={this.handlePasswordChange}
          secureTextEntry
        />
        <Button
          title="登录"
          onPress={this.handleLogin}
        />
      </View>
    );
  }
}

export default LoginPage;