Question

这不是常见的情况。我试图通过反射调用异常。我有类似的东西： testMethod的类型为MethodBuilder

testMethod.GetILGenerator().ThrowException(typeof(CustomException));

我的CustomException没有默认构造函数，因此上面的语句错误地给出了ArgumentException。如果有默认构造函数，则可以正常工作。

那么有没有办法，这可以使用没有默认的构造函数？已经尝试了2个小时了。：（

感谢任何帮助。

谢谢！

Answer 1

ThrowException方法基本归结为以下

Emit(OpCodes.NewObj, ...);
Emit(OpCodes.Throw);

这里的关键是用创建自定义异常实例所需的一组IL指令替换第一个Emit调用。然后添加Emit(OpCodes.Throw)

例如

class MyException : Exception {
  public MyException(int p1) {}
}

var ctor = typeof(MyException).GetConstructor(new Type[] {typeof(int)});
var gen = builder.GetILGenerator();
gen.Emit(OpCodes.Ldc_I4, 42);
gen.Emit(OpCodes.NewObj, ctor);
gen.Emit(OpCodes.Throw);

Answer 2

请参阅documentation：

// This example uses the ThrowException method, which uses the default 
// constructor of the specified exception type to create the exception. If you
// want to specify your own message, you must use a different constructor; 
// replace the ThrowException method call with code like that shown below,
// which creates the exception and throws it.
//
// Load the message, which is the argument for the constructor, onto the 
// execution stack. Execute Newobj, with the OverflowException constructor
// that takes a string. This pops the message off the stack, and pushes the
// new exception onto the stack. The Throw instruction pops the exception off
// the stack and throws it.
//adderIL.Emit(OpCodes.Ldstr, "DoAdd does not accept values over 100.");
//adderIL.Emit(OpCodes.Newobj, _
//             overflowType.GetConstructor(new Type[] { typeof(String) }));
//adderIL.Emit(OpCodes.Throw);

通过反射抛出异常

2 个答案: