使用PHP和UniApp实现用户登录验证的方法

<?php
   // 连接数据库
   $conn = mysqli_connect("localhost", "root", "", "users");

   // 获取用户输入的用户名和密码
   $username = $_POST['username'];
   $password = $_POST['password'];

   // 查询数据库中是否存在匹配的记录
   $result = mysqli_query($conn, "SELECT * FROM users WHERE username='$username' AND password='$password'");

   // 判断是否存在匹配的记录
   if(mysqli_num_rows($result) > 0){
      echo "登录成功";
   } else{
      echo "登录失败";
   }

   // 关闭数据库连接
   mysqli_close($conn);
?>

<template>
  <div>
    <input v-model="username" type="text" placeholder="请输入用户名" />
    <input v-model="password" type="password" placeholder="请输入密码" />
    <button @click="login">登录</button>
  </div>
</template>

<script>
export default {
  data() {
    return {
      username: '',
      password: ''
    };
  },
  methods: {
    login() {
      uni.request({
        url: 'http://localhost/login.php',
        method: 'POST',
        data: {
          username: this.username,
          password: this.password
        },
        success: res => {
          if (res.data === '登录成功') {
            uni.showToast({
              title: '登录成功',
              icon: 'success'
            });
          } else {
            uni.showToast({
              title: '登录失败',
              icon: 'none'
            });
          }
        },
        fail: err => {
          console.log(err);
        }
      });
    }
  }
};
</script>

uni.request({
  url: 'http://localhost/login.php',
  method: 'POST',
  data: {
    username: this.username,
    password: this.password
  },
  success: res => {
    if (res.data === '登录成功') {
      uni.showToast({
        title: '登录成功',
        icon: 'success'
      });
    } else {
      uni.showToast({
        title: '登录失败',
        icon: 'none'
      });
    }
  },
  fail: err => {
    console.log(err);
  }
});