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C# 随机给一个全部信息都未知的类类型，如何获取该类的类名、属性个数、属性名、属性...
source link: https://www.cnblogs.com/iZOHC/p/16243641.html
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一、场景假设
假设现在有一个泛型类T的实例对象t，该T类的全部信息都未知。
要求：打印输出实例对象t的类名、属性个数、属性名、属性的数据类型、属性值。
二、解决问题
1、我们根据输出的内容要求定义一个实体类如下：
public class GeneralDataModel
{
/// <summary>
/// 类名
/// </summary>
public string class_name { get; set; }
/// <summary>
/// 属性个数
/// </summary>
public int prop_count { get; set; }
/// <summary>
/// 单个属性的信息
/// </summary>
public List<PropInfoItem> props { get; set; }
}
public class PropInfoItem
{
/// <summary>
/// 属性名
/// </summary>
public string prop_name { get; set; }
/// <summary>
/// 属性数据类型
/// </summary>
public string prop_data_type { get; set; }
/// <summary>
/// 属性值
/// </summary>
public string prop_value { get; set; }
}2、编写一个方法，该方法的主要功能是解析实例对象t，并输出步骤1中格式的内容。方法代码实现如下：
public static GeneralDataModel DataAnalysis<T>(T t)
{
var data_type = t.GetType();
var propInfo = data_type.GetProperties();
var list = new List<PropInfoItem>();
foreach (var item in propInfo)
{
var e = new PropInfoItem
{
prop_name = item.Name,
prop_data_type = item.PropertyType.Name,
prop_value = item.GetValue(t) == null ? "" : item.GetValue(t).ToString()
};
list.Add(e);
}
var res = new GeneralDataModel
{
class_name = data_type.Name,
prop_count = propInfo.Count(),
props = list
};
return res;
}三、验证方法功能
1、假设现在有一个学生类如下所示：
public class Student
{
/// <summary>
/// 学号
/// </summary>
public int no { get; set; }
/// <summary>
/// 姓名
/// </summary>
public string name { get; set; }
/// <summary>
/// 年级
/// </summary>
public string grade { get; set; }
/// <summary>
/// 出生年月
/// </summary>
public DateTime birth { get; set; }
}2、根据该类实例化了一个st对象如下：
var st = new Student()
{
no = 123456,
name = "张三",
grade = "六年级",
birth = DateTime.Now
};3、调用DataAnalysis方法解析st，并打印输出结果：
var res = DataAnalysis(st);
Console.WriteLine(JsonConvert.SerializeObject(res));4、输出结果如下：
{
"class_name": "Student",
"prop_count": 4,
"props": [
{
"prop_name": "no",
"prop_data_type": "Int32",
"prop_value": "123456"
},
{
"prop_name": "name",
"prop_data_type": "String",
"prop_value": "张三"
},
{
"prop_name": "grade",
"prop_data_type": "String",
"prop_value": "六年级"
},
{
"prop_name": "birth",
"prop_data_type": "DateTime",
"prop_value": "2022/5/7 17:21:12"
}
]
}5、看到输出结果后，感觉完美的解决了问题。
四、变化无常
1、因为种种原因，学生类增加了两个属性，同时实例化对象的创建形式也变了，变化后的形式如下：
public class Student
{
public Student()
{
}
public Student(string id_card_no, string address)
{
this.id_card_no = id_card_no;
this.address = address;
}
/// <summary>
/// 学号
/// </summary>
public int no { get; set; }
/// <summary>
/// 姓名
/// </summary>
public string name { get; set; }
/// <summary>
/// 年级
/// </summary>
public string grade { get; set; }
/// <summary>
/// 出生年月
/// </summary>
public DateTime birth { get; set; }
/// <summary>
/// 身份证（受保护类型）
/// </summary>
protected string id_card_no { get; set; }
/// <summary>
/// 家庭地址（私有类型）
/// </summary>
private string address { get; set; }
} var st = new Student("777888202005071111", "家庭地址私有，暂时不方便透露")
{
no = 123456,
name = "张三",
grade = "六年级",
birth = DateTime.Now
};2、再次调用DataAnalysis方法解析st，并打印输出结果：
var res = DataAnalysis(st);
Console.WriteLine(JsonConvert.SerializeObject(res));3、输出结果如下：
{
"class_name": "Student",
"prop_count": 4,
"props": [
{
"prop_name": "no",
"prop_data_type": "Int32",
"prop_value": "123456"
},
{
"prop_name": "name",
"prop_data_type": "String",
"prop_value": "张三"
},
{
"prop_name": "grade",
"prop_data_type": "String",
"prop_value": "六年级"
},
{
"prop_name": "birth",
"prop_data_type": "DateTime",
"prop_value": "2022/5/7 17:40:21"
}
]
}4、看到输出结果时，咦？怎么似乎好像哪里不对？新增的两个属性怎么没有被解析并输出呢？
五、反射了解一下？
1、通过种种途径或者查阅其他资料你了解到了反射的相关知识，并找到了一个名为GetRuntimeProperties的方法。
2、修改原先的解析方法代码如下：
public static GeneralDataModel DataAnalysis<T>(T t)
{
var data_type = t.GetType();
var refPropInfo = data_type.GetRuntimeProperties();
var list = new List<PropInfoItem>();
foreach (var item in refPropInfo)
{
var e = new PropInfoItem
{
prop_name = item.Name,
prop_data_type = item.PropertyType.Name,
prop_value = item.GetValue(t) == null ? "" : item.GetValue(t).ToString()
};
list.Add(e);
}
var res = new GeneralDataModel
{
class_name = data_type.Name,
prop_count = refPropInfo.Count(),
props = list
};
return res;
}3、再一次调用DataAnalysis方法解析st，并打印输出结果：
var res = DataAnalysis(st);
Console.WriteLine(JsonConvert.SerializeObject(res));4、输出结果如下：
{
"class_name": "Student",
"prop_count": 6,
"props": [
{
"prop_name": "no",
"prop_data_type": "Int32",
"prop_value": "123456"
},
{
"prop_name": "name",
"prop_data_type": "String",
"prop_value": "张三"
},
{
"prop_name": "grade",
"prop_data_type": "String",
"prop_value": "六年级"
},
{
"prop_name": "birth",
"prop_data_type": "DateTime",
"prop_value": "2022/5/7 17:52:12"
},
{
"prop_name": "id_card_no",
"prop_data_type": "String",
"prop_value": "777888202005071111"
},
{
"prop_name": "address",
"prop_data_type": "String",
"prop_value": "家庭地址暂时不方便透露"
}
]
}5、看到这输出结果，脸上露出了满意的笑容，啊~~~问题终于解决了，开森^_^
六、前后对比并溯源
1、方法前后变化仅仅只有一处，由GetProperties变为了GetRuntimeProperties。
2、溯源发现：
- GetProperties：在System命名空间下，是Type类的实例方法。
- GetRuntimeProperties（Type类的扩展方法）：在System.Reflection命名空间下，是RuntimeReflectionExtensions类的静态方法。
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