尝试抓住最后扔

try，catch，finally 和 throw 允许你处理代码中的异常。

var processor = new InputProcessor();

// The code within the try block will be executed. If an exception occurs during execution of
// this code, execution will pass to the catch block corresponding to the exception type.
try 
{
    processor.Process(input);
}
// If a FormatException is thrown during the try block, then this catch block
// will be executed.
catch (FormatException ex)
{
    // Throw is a keyword that will manually throw an exception, triggering any catch block that is
    // waiting for that exception type. 
    throw new InvalidOperationException("Invalid input", ex);
}
// catch can be used to catch all or any specific exceptions. This catch block,
// with no type specified, catches any exception that hasn't already been caught
// in a prior catch block.
catch
{
    LogUnexpectedException(); 
    throw; // Re-throws the original exception.
}
// The finally block is executed after all try-catch blocks have been; either after the try has
// succeeded in running all commands or after all exceptions have been caught. 
finally
{
    processor.Dispose();
}

注意： return 关键字可以在 try 块中使用，finally 块仍然会被执行（就在返回之前）。例如：

try 
{
    connection.Open();
    return connection.Get(query);
} 
finally 
{
    connection.Close();
}

声明 connection.Close() 将在返回 connection.Get(query) 的结果之前执行。