一、定义抽象类及子类，WebMethod实际返回子类参数
//使用XmlInclude解决WebService调用时无法识别子类的异常
[System.Xml.Serialization.XmlInclude(typeof(WageEmploeyee)), System.Xml.Serialization.XmlInclude(typeof(Boss))]
public abstract class EmployeeData
{
//Required by XmlSerializer
public EmployeeData() { } public string Name { get; set; } public string SSN { get; set; } public abstract double ComputerPay();
} public class WageEmploeyee : EmployeeData
{
public double Wage { get; set; } public double Hours { get; set; } public override double ComputerPay()
{
return this.Wage * this.Hours;
}
} public class Boss : EmployeeData
{
public double Salary { get; set; } public override double ComputerPay()
{
return this.Salary;
}
}
2、WebMethod方法（根据传入的参数实例化不同的子类）
public class WebService1 : System.Web.Services.WebService
{ [WebMethod]
public EmployeeData GetEmployee(int id)
{
if (id == )
{
return new Boss();
} return new WageEmploeyee();
}
}