ABP学习入门系列（四）（创建Service）

一，一些相关解释

Service 在应用服务层也就是application层。应用服务用于将领域(业务)逻辑暴露给展现层。展现层通过传入DTO(数据传输对象)参数来调用应用服务，而应用服务通过领域对象来执行相应的业务逻辑并且将DTO返回给展现层。

也就是这样避免了应用服务层和展现层的，直接数据交互，而是通过dto实现了数据过滤，这样就可以较好的避免非法数据的传入传出。另外大头还要实现数据隐藏，方便扩展等好处。

创建应用服务时需要注意：

1.service 要实现IApplicationService接口。

2，ABP为IApplicationService提供默认实现ApplicationService

3，ABP中，一个应用服务方法默认是一个工作单元（Unit of Work）。ABP针对UOW模式自动进行数据库的连接及事务管理，且会自动保存数据修改。

二，XXService和IXXService

1，如下TaskAppService 继承了LearningMpaAbpAppServiceBase，并实现了ITaskAppService接口

using Abp.Application.Services.Dto;
using Abp.Authorization;
using Abp.AutoMapper;
using Abp.Domain.Repositories;
using Abp.Events.Bus;
using Abp.Extensions;
using Abp.Linq.Extensions;
using Abp.Net.Mail.Smtp;
using Abp.Notifications;
using Abp.Runtime.Session;
using AutoMapper;
using LearningMpaAbp.Authorization;
using LearningMpaAbp.Authorization.Users;
using LearningMpaAbp.Tasks.Dtos;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Dynamic.Core;
using System.Threading.Tasks;

namespace LearningMpaAbp.Tasks
{
    /// <summary>
    ///     Implements <see cref="ITaskAppService" /> to perform task related application functionality.
    ///     Inherits from <see cref="ApplicationService" />.
    ///     <see cref="ApplicationService" /> contains some basic functionality common for application services (such as
    ///     logging and localization).
    /// </summary>
    public class TaskAppService : LearningMpaAbpAppServiceBase, ITaskAppService
    {
        private readonly INotificationPublisher _notificationPublisher;
        private readonly ISmtpEmailSender _smtpEmailSender;
        //These members set in constructor using constructor injection.

        private readonly IRepository<Task> _taskRepository;
        private readonly IRepository<User, long> _userRepository;
        private readonly ITaskManager _taskManager;
        private readonly ITaskCache _taskCache;
        private readonly IEventBus _eventBus;

        /// <summary>
        ///     In constructor, we can get needed classes/interfaces.
        ///     They are sent here by dependency injection system automatically.
        /// </summary>
        public TaskAppService(
            IRepository<Task> taskRepository,
            IRepository<User, long> userRepository,
            ISmtpEmailSender smtpEmailSender,
            INotificationPublisher notificationPublisher,
            ITaskCache taskCache,
            ITaskManager taskManager,
            IEventBus eventBus)
        {
            _taskRepository = taskRepository;
            _userRepository = userRepository;
            _smtpEmailSender = smtpEmailSender;
            _notificationPublisher = notificationPublisher;
            _taskCache = taskCache;
            _taskManager = taskManager;
            _eventBus = eventBus;
        }

        public TaskCacheItem GetTaskFromCacheById(int taskId)
        {
            return _taskCache[taskId];
        }

        public IList<TaskDto> GetAllTasks()
        {
            var tasks = _taskRepository.GetAll().OrderByDescending(t => t.CreationTime).ToList();
            return Mapper.Map<IList<TaskDto>>(tasks);
        }

        public GetTasksOutput GetTasks(GetTasksInput input)
        {
            var query = _taskRepository.GetAllIncluding(t => t.AssignedPerson)
                .WhereIf(input.State.HasValue, t => t.State == input.State.Value)
                .WhereIf(!input.Filter.IsNullOrEmpty(), t => t.Title.Contains(input.Filter))
                .WhereIf(input.AssignedPersonId.HasValue, t => t.AssignedPersonId == input.AssignedPersonId.Value);

            //排序
            if (!string.IsNullOrEmpty(input.Sorting))
                query = query.OrderBy(input.Sorting);
            else
                query = query.OrderByDescending(t => t.CreationTime);

            var taskList = query.ToList();

            //Used AutoMapper to automatically convert List<Task> to List<TaskDto>.
            return new GetTasksOutput
            {
                Tasks = Mapper.Map<List<TaskDto>>(taskList)
            };
        }

        public PagedResultDto<TaskDto> GetPagedTasks(GetTasksInput input)
        {
            //初步过滤
            var query = _taskRepository.GetAllIncluding(t => t.AssignedPerson)
                .WhereIf(input.State.HasValue, t => t.State == input.State.Value)
                .WhereIf(!input.Filter.IsNullOrEmpty(), t => t.Title.Contains(input.Filter))
                .WhereIf(input.AssignedPersonId.HasValue, t => t.AssignedPersonId == input.AssignedPersonId.Value);

            //排序
            query = !string.IsNullOrEmpty(input.Sorting) ? query.OrderBy(input.Sorting) : query.OrderByDescending(t => t.CreationTime);

            //获取总数
            var tasksCount = query.Count();
            //默认的分页方式
            //var taskList = query.Skip(input.SkipCount).Take(input.MaxResultCount).ToList();

            //ABP提供了扩展方法PageBy分页方式
            var taskList = query.PageBy(input).ToList();

            return new PagedResultDto<TaskDto>(tasksCount, taskList.MapTo<List<TaskDto>>());
        }

        public async Task<TaskDto> GetTaskByIdAsync(int taskId)
        {
            //Called specific GetAllWithPeople method of task repository.
            var task = await _taskRepository.GetAsync(taskId);

            //Used AutoMapper to automatically convert List<Task> to List<TaskDto>.
            return task.MapTo<TaskDto>();
        }

        public TaskDto GetTaskById(int taskId)
        {
            var task = _taskRepository.Get(taskId);

            return task.MapTo<TaskDto>();
        }

        public void UpdateTask(UpdateTaskInput input)
        {
            //We can use Logger, it's defined in ApplicationService base class.
            Logger.Info("Updating a task for input: " + input);

            //获取是否有权限
            bool canAssignTaskToOther = PermissionChecker.IsGranted(PermissionNames.Pages_Tasks_AssignPerson);
            //如果任务已经分配且未分配给自己，且不具有分配任务权限，则抛出异常
            if (input.AssignedPersonId.HasValue && input.AssignedPersonId.Value != AbpSession.GetUserId() &&
                !canAssignTaskToOther)
            {
                throw new AbpAuthorizationException("没有分配任务给他人的权限！");
            }

            var updateTask = Mapper.Map<Task>(input);
            var user = _userRepository.Get(input.AssignedPersonId.Value);
            //先执行分配任务
            _taskManager.AssignTaskToPerson(updateTask, user);

            //再更新其他字段
            _taskRepository.Update(updateTask);

        }

        public void AssignTaskToPerson(AssignTaskToPersonInput input)
        {
            var task = _taskRepository.Get(input.TaskId);
            var user = _userRepository.Get(input.UserId);
            _taskManager.AssignTaskToPerson(task, user);
            //这里有一个问题就是，当开发人员不知道有这个TaskManager时，依然可以通过直接修改Task的AssignedPersonId属性就行任务分配。

            //分配任务成功后，触发领域事件，发送邮件通知
            //_eventBus.Trigger(new TaskAssignedEventData(task, user));//由领域服务触发领域事件

        }

        public int CreateTask(CreateTaskInput input)
        {
            //We can use Logger, it's defined in ApplicationService class.
            Logger.Info("Creating a task for input: " + input);

            //判断用户是否有权限
            if (input.AssignedPersonId.HasValue && input.AssignedPersonId.Value != AbpSession.GetUserId())
                PermissionChecker.Authorize(PermissionNames.Pages_Tasks_AssignPerson);

            var task = Mapper.Map<Task>(input);

            int result = _taskRepository.InsertAndGetId(task);

            //只有创建成功才发送邮件和通知
            if (result > 0)
            {
                if (input.AssignedPersonId.HasValue)
                {
                    var user = _userRepository.Load(input.AssignedPersonId.Value);
                    //task.AssignedPerson = user;
                    //var message = "You hava been assigned one task into your todo list.";

                    //使用领域事件触发发送通知操作
                    _eventBus.Trigger(new TaskAssignedEventData(task, user));

                    //TODO:需要重新配置QQ邮箱密码
                    //_smtpEmailSender.Send("ysjshengjie@qq.com", task.AssignedPerson.EmailAddress, "New Todo item", message);

                    //_notificationPublisher.Publish("NewTask", new MessageNotificationData(message), null,
                    //    NotificationSeverity.Info, new[] { task.AssignedPerson.ToUserIdentifier() });
                }
            }

            return result;
        }

        public void Delete(int id)
        {
            var task = _taskRepository.Get(id);
            if (task != null)
                _taskRepository.Delete(task);
        }
    }
}

2，ITaskAppService 继承IApplicationService

using System.Collections.Generic;
using System.Linq;
using System.Linq.Dynamic;
using System.Threading.Tasks;
using Abp.Application.Services;
using Abp.Application.Services.Dto;
using Abp.Linq.Extensions;
using LearningMpaAbp.Tasks.Dtos;

namespace LearningMpaAbp.Tasks
{
    public interface ITaskAppService : IApplicationService
    {
        GetTasksOutput GetTasks(GetTasksInput input);

        PagedResultDto<TaskDto> GetPagedTasks(GetTasksInput input);

        void UpdateTask(UpdateTaskInput input);

        int CreateTask(CreateTaskInput input);

        Task<TaskDto> GetTaskByIdAsync(int taskId);

        TaskDto GetTaskById(int taskId);

        void Delete(int taskId);

        TaskCacheItem GetTaskFromCacheById(int taskId);

        IList<TaskDto> GetAllTasks();
    }
}

三，Dto 数据传输对象(Data Transfer Objects)用于应用层和展现层的数据传输

ABP 建议命名 input/ouput 对象类似于 MethodNameInput/MethodNameOutput，对于每个应用服务方法都需要将 Input 和 Output 进行分开定义。甚至你的方法只接
收或者返回一个值，也最好创建相应的 DTO 类型。 这样会使代码有更好的扩展性

using System.Collections.Generic;

namespace LearningMpaAbp.Tasks.Dtos
{
    public class GetTasksOutput
    {
        public List<TaskDto> Tasks { get; set; }
    }
}

有一个问题怎么将task实体类转换为dto，这时就需要进行映射了AutoMapper 根据 Task实体创建了 taskDto,并根据命名约定来给
PersonDto 的属性赋值 。

以上。。

参考：http://www.jianshu.com/p/da69ca7b27c6

代码：https://github.com/tianxiangd/LearnAbp