AutoMapper高效实现对象映射

# 创建控制台应用AutoMapperSample
```xml
<PackageReference Include="AutoMapper" Version="13.0.1" ></PackageReference>
<PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0" ></PackageReference>
```
# 创建实体、DTO类
```java
namespace AutoMapperSample.Entities
{
    public class Person
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime DateOfBirth { get; set; }
    }
}
namespace AutoMapperSample.Dtos
{
    public class PersonDto
    {
        public int Id { get; set; }
        public string FullName { get; set; }
        public int Age { get; set; }
    }
}
```
# 映射规则
```java
namespace AutoMapperSample
{
    /// <summary>
    /// 配置映射规则
    /// </summary>
    public class AutoMappingProfile : Profile
    {
        public AutoMappingProfile()
        {
            // 配置源类型和目标类型
            CreateMap<Person, PersonDto>()
                // 自定义转换规则
                .ForMember(dest => dest.FullName, opt => opt.MapFrom(src => $"{src.FirstName} {src.LastName}"))
                .ForMember(dest => dest.Age, opt => opt.MapFrom(src => CalculateAge(src.DateOfBirth)));
        }

/// <summary>
        /// 根据出生日期计算年龄
        /// </summary>
        /// <param name="dateOfBirth"></param>
        /// <returns></returns>
        private int CalculateAge(DateTime dateOfBirth)
        {
            return (DateTime.Today.Year - dateOfBirth.Year) - ((DateTime.Today.Month < dateOfBirth.Month) ? 1 : 0);
        }
    }
}
```
# 服务
```java
namespace AutoMapperSample
{
    public class PersonService
    {
        private readonly IMapper _mapper;

/// <summary>
        /// 在构造方法中注入 IMapper
        /// </summary>
        /// <param name="mapper"></param>
        public PersonService(IMapper mapper)
        {
            _mapper = mapper;
        }

public void DoMapping()
        {
            // 假设从数据库查询到用户实体
            var personEntity = new Person
            {
                Id = 1,
                FirstName = "Jacky",
                LastName = "Yang",
                DateOfBirth = new DateTime(1990, 1, 1)
            };

// 使用 AutoMapper 进行转换，将 personEntity 对象映射为 PersonDto 类型
            var personDto = _mapper.Map<PersonDto>(personEntity);

// 输出映射结果
            Console.WriteLine($"Full Name: {personDto.FullName}");
            Console.WriteLine($"Age: {personDto.Age}");
        }
    }
}
```

# 注入服务
```java
// 创建依赖注入容器 ServiceCollection
ServiceCollection services = new ServiceCollection();

// 注入 AutoMapper 服务
services.AddAutoMapper(typeof(AutoMappingProfile));

// 注入 PersonService
services.AddTransient<PersonService>();

// 执行 PersonService 中的方法
using (ServiceProvider sp = services.BuildServiceProvider())
{
    // 服务定位器模式，通过 GetRequiredService 获取 PersonService 对象
    var ps = sp.GetRequiredService<PersonService>();
    ps.DoMapping();
}
```