NetCore项目实战篇02---全局异常处理

在 .netcore中可以自定义自己的异常类型，步骤如下：

1、自定义自己的异常类型UserOperationException 并继承自Exception

public class UserOperationException:Exception
{
public UserOperationException() { }

public UserOperationException(string message) : base(message) { }

public UserOperationException(string message, Exception innerException) : base(message, innerException) { }
}

2、自定义自己的全局异常过滤器GlobalExceptionFilter 实现接口 IExceptionFilter

public class GlobalExceptionFilter : IExceptionFilter
{
private readonly IHostingEnvironment _env;
private readonly ILogger<GlobalExceptionFilter> _logger;
public GlobalExceptionFilter(IHostingEnvironment env, ILogger<GlobalExceptionFilter> logger)
{
_env = env;
_logger = logger;
}
public void OnException(ExceptionContext context)
{
var json = new JsonErrorResponse
{
Message = context.Exception.Message
};
if (context.Exception.GetType() == typeof(UserOperationException))
{

context.Result = new BadRequestObjectResult(json);
}else
{
json.Message = "zhengweiProject中发生了未知的内部异常！";
if(_env.IsDevelopment())
{
json.Message = context.Exception.StackTrace;
}
context.Result = new InternalServerErrorObjectResult(json);
}
_logger.LogError(context.Exception, context.Exception.Message);
context.ExceptionHandled = true;
}
}

public class InternalServerErrorObjectResult:ObjectResult
{
public InternalServerErrorObjectResult(object error):base(error)
{
StatusCode = StatusCodes.Status500InternalServerError;
}
}

3、在项目中使用，第一篇文章已说过，项目使用微服务webapi架构。新建控制器UserController.cs 在get方法中抛出异常，

在获取UserIdentity值时故意获取了数据库中没有的值

[Route("api/users")]
public class UserController : BaseController
{
public UserContext _userContext;
public UserController(UserContext userContext)
{
_userContext = userContext;
}
// GET api/values
[Route("")]
[HttpGet]
public async Task<IActionResult> Get()
{
var user =_userContext.Users.SingleOrDefault(u=>u.Id == UserIdentity.UserId);
if(user == null)
{
throw new UserOperationException("获取用户数据出错，用户ID:"+UserIdentity.UserId);

}
return Json(user);
}

// GET api/values/5
[HttpGet("{id}")]
public string Get(int id)
{
return "value";
}

// POST api/values
[Route("")]
[HttpPost]
public void Post([FromBody]string value)
{
}

// PUT api/values/5
[Route("")]
[HttpPut("{id}")]
public void Put(int id, [FromBody]string value)
{
}

// DELETE api/values/5
[HttpDelete("{id}")]
public void Delete(int id)
{
}
}

4、运行项目后，postman访问API，结果如下：