C#中如何使用字符串变量构建限定类名并访问对应属性

你明确知晓所有嵌套类结构的前提下，优先使用编译时安全的委托映射方案，避免反射的性能损耗和运行时风险。

方案1：委托字典映射（最推荐） #

提前把属性名对应的读写逻辑存在字典中，循环时直接调用即可，执行效率和硬编码完全一致，且编译时会做类型校验。

// 1. 提前定义映射，仅需初始化一次，注意替换代码中的GeographiesType、CensusReturnType为你实际的类名
private static readonly Dictionary<string, Func<GeographiesType, string>> _geoValueGetter = new()
{
    ["CensusBlocks"] = geo => geo.CensusBlocks[0].BLOCK,
    ["_111thCongressionalDistricts"] = geo => geo._111thCongressionalDistricts[0].BLOCK,
    ["CensusTracts"] = geo => geo.CensusTracts[0].BLOCK,
    ["Counties"] = geo => geo.Counties[0].BLOCK,
    ["StateLegislativeDistrictsLower"] = geo => geo.StateLegislativeDistrictsLower[0].BLOCK,
    ["StateLegislativeDistrictsUpper"] = geo => geo.StateLegislativeDistrictsUpper[0].BLOCK,
    ["CountySubdivisions"] = geo => geo.CountySubdivisions[0].BLOCK,
    ["States"] = geo => geo.States[0].BLOCK
};

private static readonly Dictionary<string, Action<CensusReturnType, string>> _censusValueSetter = new()
{
    ["CensusBlocks"] = (cr, val) => cr.CensusBlocks.Name = val,
    ["_111thCongressionalDistricts"] = (cr, val) => cr._111thCongressionalDistricts.Name = val,
    ["CensusTracts"] = (cr, val) => cr.CensusTracts.Name = val,
    ["Counties"] = (cr, val) => cr.Counties.Name = val,
    ["StateLegislativeDistrictsLower"] = (cr, val) => cr.StateLegislativeDistrictsLower.Name = val,
    ["StateLegislativeDistrictsUpper"] = (cr, val) => cr.StateLegislativeDistrictsUpper.Name = val,
    ["CountySubdivisions"] = (cr, val) => cr.CountySubdivisions.Name = val,
    ["States"] = (cr, val) => cr.States.Name = val
};

// 2. 循环逻辑实现
string[] items =
{
    "CensusBlocks",
    "_111thCongressionalDistricts",
    "CensusTracts",
    "Counties",
    "StateLegislativeDistrictsLower",
    "StateLegislativeDistrictsUpper",
    "CountySubdivisions",
    "States"
};

var geographies = records.result.addressMatches[0].geographies;
foreach (var item in items)
{
    var blockValue = _geoValueGetter[item](geographies);
    _censusValueSetter[item](censusreturn, blockValue);
}

方案2：动态类型访问（适合快速开发场景） #

如果不想写映射代码，可使用dynamic关键字绕过编译时类型检查，适合属性结构不稳定、临时开发的场景，缺点是编译时不会校验属性正确性，运行时出错概率更高：

string[] items =
{
    "CensusBlocks",
    "_111thCongressionalDistricts",
    "CensusTracts",
    "Counties",
    "StateLegislativeDistrictsLower",
    "StateLegislativeDistrictsUpper",
    "CountySubdivisions",
    "States"
};

dynamic geoDynamic = records.result.addressMatches[0].geographies;
dynamic censusDynamic = censusreturn;
foreach (var item in items)
{
    // 注意：如果是强类型类，该写法实际底层仍会调用反射，性能低于方案1
    var blockValue = geoDynamic.GetType().GetProperty(item).GetValue(geoDynamic)[0].BLOCK;
    var censusProp = censusDynamic.GetType().GetProperty(item).GetValue(censusDynamic);
    censusProp.GetType().GetProperty("Name").SetValue(censusProp, blockValue);
}

如果你的geographies和censusreturn是JSON反序列化得到的JObject类对象，可以直接用索引访问，写法更简洁：

foreach (var item in items)
{
    var blockValue = geographies[item][0]["BLOCK"].ToString();
    censusreturn[item]["Name"] = blockValue;
}

内容的提问来源于stack exchange，提问作者John Miller