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CSharp补课笔记TypeConverter

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实现不同类型之间的转换, 如动态的将字符串转换为对象实例

示例

使用示例

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public void TestTypeConvert()
{
    TypeConverter tc = TypeDescriptor.GetConverter(typeof(ColorRGB));

    ColorRGB colorRGB1 = (ColorRGB)tc.ConvertFromString("#FF8800");
    ColorRGB colorRGB2 = (ColorRGB)tc.ConvertFromString("255, 136, 0");

    string colorString1 = tc.ConvertToString(colorRGB1);
    string colorString2 = tc.ConvertToString(colorRGB2);
}

自定义类型

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//将转换器与目标类型关联
[TypeConverter(typeof(ColorRGBConverter))]
public class ColorRGB
{
    public byte R; public byte G; public byte B;
    public ColorRGB(byte r, byte g, byte b)
    { R = r; G = g; B = b; }
    public override string ToString()
    {
        return string.Format("#{0:X2}{1:X2}{2:X2}", R, G, B);
    }
}

定义类型转换器

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internal class ColorRGBConverter : TypeConverter
{
    //定义可以从哪些类型转换
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(string);
    }

    public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
    {
        return base.CanConvertTo(context, destinationType);
    }

    //实现将字符串转化为对象
    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        if(value is string strValue)
        {
            try
            {
                if(strValue.StartsWith("#"))
                {
                    if (strValue.Length == 7)
                        return new ColorRGB(byte.Parse(strValue.Substring(1,2), NumberStyles.HexNumber),
                                            byte.Parse(strValue.Substring(3,2), NumberStyles.HexNumber),
                                            byte.Parse(strValue.Substring(5,2), NumberStyles.HexNumber));                        
                }
                else
                {
                    string[] parts = strValue.Split(',');
                    return new ColorRGB(byte.Parse(parts[0].Trim()),
                                        byte.Parse(parts[1].Trim()),
                                        byte.Parse(parts[2].Trim()));
                }
            }
            catch 
            {
                throw new FormatException("格式不正确");
            }
        }
        return base.ConvertFrom(context, culture, value);
    }

    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        if(value is ColorRGB && destinationType == typeof(string))
            return value.ToString();
        return base.ConvertTo(context, culture, value, destinationType);
    }
}

扩展

CultureInfo主要用于特定区域的数字, 日期, 货币等格式化设置