1、示例：

2、代码：

只看核心代码块 其他不用管

<template>
	<view class="page">
		<view class="top-background-raduis"> </view>
		<view class="login-box">
			<view class="login-card-title">
				<view class="login-card-title-content"> 账号密码登录 </view>
			</view>
			<view class="login-card-input">
				<!-- 输入框头部图标 -->
				<uni-easyinput class="hj-input" v-model="user.userName" focus maxlength="30" :trim="true"
				 placeholder="请输入账号"></uni-easyinput>
				<!-- 输入框头部图标 -->
				<uni-easyinput class="hj-input" v-model="user.password" type="password"
					 placeholder="请输入密码"></uni-easyinput>
			</view>
			<!-- 记住密码功能 -->
			<view class="remember-psw">
				<checkbox-group>
					<checkbox type="checkbox"  :checked='rememberPsw' @click="rememberPsw = !rememberPsw" color="#09CC86"/>
					记住账号密码
				</checkbox-group>
			</view>

			<view class="login-card-loginIn">
				<view class="login-card-loginIn-btn" @click="login">
					登录
				</view>
			</view>
		</view>
		<view class="bottom-message">
			版权所有 示例
		</view>
	</view>
</template>

	import {
		login
	} from "@/pages/login/api/api.js";
	export default {
		data() {
			return {
				rememberPsw: true,//复选框状态 默认勾选
				user: {
					userName: '',//账号
					password: ''//密码
				}
			};
		},
		mounted() {
			//取出缓存中的账号、密码
			const HBusername = uni.getStorageSync('HBusername');
			const HBpassword = uni.getStorageSync('HBpassword');
			console.log("缓存的账号:",HBusername)
			console.log("缓存的密码:",HBpassword)
			//有账号、密码就赋值给文本，没有就清空
			if (HBusername && HBpassword) {
				this.user.userName = HBusername;
				this.user.password = HBpassword;
			}
		},
		methods: {
			//登录
			login() {
				if (this.auth()) {
					login(this.user).then(res => {
						if (res.code == '200') {
						   //勾选就缓存账号、密码
							if (this.rememberPsw) {
								uni.setStorageSync('HBusername', this.user.userName);
								uni.setStorageSync('HBpassword', this.user.password);
							} else {//销毁缓存中的账号、密码
								uni.removeStorageSync('HBusername');
								uni.removeStorageSync('HBpassword');
							}
							uni.showToast({icon: 'none',title: '登录成功'});
							uni.setStorageSync('Admin-Token', res.token);
							setTimeout(() => {
								uni.reLaunch({
									url: '/pages/cyjy/home', //跳转首页
								})
							}, 500);
						}else {
							uni.showToast({icon: 'none',title: '登录失败'});
						}
					}).catch(err => {
						console.log(err)
					})
				}
			},
			//校验
			auth() {
				if (this.user.userName.length < 1 || this.user.userName == '' && this.user.password.length < 1 || this.user.password == '') {
		            uni.showToast({icon: 'none',title: '请输入用户名与密码'});
					return false;
				}
				if (this.user.userName.length < 1 || this.user.userName == '') {
					uni.showToast({icon: 'none',title: '请输入用户名'});
					return false;
				}
				if (this.user.password.length < 1 || this.user.password == '') {
					uni.showToast({icon: 'none',title: '请输入密码'});
					return false;
				}
				return true;
			},
		},
}

3、步骤逻辑：

第一次登录输入账号密码默认是勾选记住账号密码的，登录会将账号密码存入进缓存。（复选框做了缓存的存入与销毁，勾选就将账号密码存入缓存，不勾选就销毁缓存。）

账号 key：HBusername
密码 key：HBpassword

第二次及往后每次登录，都会先从缓存中获取账号密码key，将账号密码填充进文本框，没有就不填充。