以相同的方法拋出並捕獲異常

Question

在我寫入數據庫的方法中，我處理錯誤，如下面的代碼所示。在catch (DbUpdateException ex)我想重新拋出異常並在最後的catch (Exception ex)中捕獲它。

這是可能的，以及如何做到這一點？下面的代碼不這樣做。

 using (Entities context = new Entities()) 
     { 
      try 
      { 
       context.Office.Add(office); 
       retVal = context.SaveChanges(); 
      } 
      catch (DbUpdateException ex) 
      { 
       SqlException innerException = ex.GetBaseException() as SqlException; 
       if (innerException != null && innerException.Number == (int)SQLErrorCode.DUPLICATE_UNIQUE_CONSTRAINT) 
       { 
        throw 
         new Exception("Error ocurred"); 
       } 
       //This is momenty where exception is thrown. 
       else 
       { 
        throw ex; 
       } 
      } 
      catch (Exception ex) 
      { 
       throw 
        new Exception("Error"); 
      } 
     } 

Answer 1

你試圖嘗試築巢你try...catch塊？

using (Entities context = new Entities()) 
    { 
     try 
     { 
      try 
      { 
       context.Office.Add(office); 
       retVal = context.SaveChanges(); 
      } 
      catch (DbUpdateException ex) 
      { 
       SqlException innerException = ex.GetBaseException() as SqlException; 
       if (innerException != null && innerException.Number == (int)SQLErrorCode.DUPLICATE_UNIQUE_CONSTRAINT) 
       { 
        throw new Exception("Error ocurred"); 
       } 
       //This is momenty where exception is thrown. 
       else 
       { 
        throw ex; 
       } 
      } 
     } 
     catch (Exception ex) 
     { 
      throw new Exception("Error"); 
     } 
    } 

Answer 2

下會更好：

context.Office.Add(office); 
retVal = context.SaveChanges(); 

讓除泡了。如果你所要做的只是重新拋棄，就不需要去捕捉東西。

注意：throw ex;將重置堆棧跟蹤 - 您想正常執行throw;。當你打電話給你的方法用try catch塊括起來

try 
{ 
    YourMethod() 
} 
catch (Exception ex) 
{ 
    throw 
     new Exception("Error"); 
} 

Answer 3

試試這個。因此，如果你真的需要這個功能，你需要把一個try-catch內一個try-catch的，就像這樣：

using (Entities context = new Entities()) 
{ 
    try 
    { 
     try 
     { 
      context.Office.Add(office); 
      retVal = context.SaveChanges(); 
     } 
     catch (DbUpdateException ex) 
     { 
      SqlException innerException = ex.GetBaseException() as SqlException; 
      if (innerException != null && innerException.Number == (int)SQLErrorCode.DUPLICATE_UNIQUE_CONSTRAINT) 
      { 
       throw 
        new Exception("Error ocurred"); 
      } 
      //This is momenty where exception is thrown. 
      else 
      { 
       throw ex; 
      } 
     } 
    } 
    catch (Exception ex) 
    { 
     throw 
      new Exception("Error"); 
    } 

} 

Answer 4

一個try-catch只處理一個 catch塊，它們按順序計算

void YourMethod() 
{ 
using (Entities context = new Entities()) 
     { 
      try 
      { 
       context.Office.Add(office); 
       retVal = context.SaveChanges(); 
      } 
      catch (DbUpdateException ex) 
      { 
       SqlException innerException = ex.GetBaseException() as SqlException; 
       if (innerException != null && innerException.Number == (int)SQLErrorCode.DUPLICATE_UNIQUE_CONSTRAINT) 
       { 
        throw 
         new Exception("Error ocurred"); 
       } 
       //This is momenty where exception is thrown. 
       else 
       { 
        throw ex; 
       } 
      } 
     } 
} 

然後：

Answer 5

如果您想從其他捕獲中捕獲異​​常，則它們不能處於同一級別。

您當前的代碼有這樣的結構：

try 
{ 
} 
catch (...) 
{ 
} 
catch (...) 
{ 
} 

您需要將其更改爲：

try 
{ 

    try 
    { 
    } 
    catch (...) 
    { 
     // throw X 
    }     
} 
catch (...) 
{ 
    // catch X here 
} 

但是，你應該非常小心，如果你真的想/需要這樣認爲。它看起來不像一個高效的錯誤處理模式。

並參見this answer爲4種不同的方式來（重新）拋出異常及其後果。

Answer 6

當你計劃你的嵌套的try-catch塊如由「保羅」知道的異常類型：

using (Entities context = new Entities())  
{   
    try 
    { 
     try 
     { 
      context.Office.Add(office); 
      retVal = context.SaveChanges(); 
     } 
     catch (DbUpdateException ex) 
     { 
      SqlException innerException = ex.GetBaseException() as SqlException; 
      if (innerException != null && innerException.Number == (int)SQLErrorCode.DUPLICATE_UNIQUE_CONSTRAINT) 
      { 
       // this exception will be catched too in outer try-catch block <-------- 
       throw new Exception("Error ocurred"); 
      } 
      //This is momenty where exception is thrown. 
      else 
      { 
       throw ex; 
      } 
     } 
    } 
    // Catch (DbUpdateException ex) if you plan to have the rethrown exception to be catched <------------ 
    catch (Exception ex) 
    { 
     throw new Exception("Error"); 
    } 

}