Angularjs表单验证，基于服务响应show error msg

app.service('FormValidationService', function() {
  this.validateForm = function(formData) {
    var errors = [];

    // 在这里添加表单验证逻辑
    if (formData.username === '') {
      errors.push('用户名不能为空');
    }
    if (formData.password === '') {
      errors.push('密码不能为空');
    }

    return errors;
  };
});

app.controller('FormController', function($scope, FormValidationService) {
  $scope.formData = {
    username: '',
    password: ''
  };
  $scope.errors = [];

  $scope.submitForm = function() {
    $scope.errors = FormValidationService.validateForm($scope.formData);
  };
});

<form ng-controller="FormController" ng-submit="submitForm()">
  <div>
    <label>用户名:</label>
    <input type="text" ng-model="formData.username" required>
  </div>
  <div>
    <label>密码:</label>
    <input type="password" ng-model="formData.password" required>
  </div>
  <div ng-show="errors.length > 0">
    <ul>
      <li ng-repeat="error in errors">{{ error }}</li>
    </ul>
  </div>
  <button type="submit">提交</button>
</form>