使用C#基于System.Text.Json实现多格式JSON转通用结构

下面提供两种可行的实现方案，适配你的需求：

方案一：基于JSON DOM（JsonDocument）的灵活转换 #

这种方法无需定义输入模型，直接解析JSON节点进行映射，适合结构多变的场景：

using System.Text.Json;

// 定义目标通用模型
public class Person
{
    [JsonPropertyName("First_Name")]
    public string FirstName { get; set; }
    
    [JsonPropertyName("Last_Name")]
    public string LastName { get; set; }
}

public class PersonRoot
{
    [JsonPropertyName("Person")]
    public List<Person> People { get; set; }
}

public static PersonRoot ConvertToPersonJson(string vendorJson)
{
    var personList = new List<Person>();
    
    using var doc = JsonDocument.Parse(vendorJson);
    var root = doc.RootElement;
    
    // 遍历根节点下的所有属性，找到数组类型的节点（Students/Employee）
    foreach (var property in root.EnumerateObject())
    {
        if (property.Value.ValueKind == JsonValueKind.Array)
        {
            foreach (var item in property.Value.EnumerateArray())
            {
                var person = new Person();
                
                // 根据不同的字段名映射
                if (item.TryGetProperty("FirstName", out var firstName))
                {
                    person.FirstName = firstName.GetString();
                    person.LastName = item.GetProperty("LastName").GetString();
                }
                else if (item.TryGetProperty("FName", out var fName))
                {
                    person.FirstName = fName.GetString();
                    person.LastName = item.GetProperty("LName").GetString();
                }
                
                personList.Add(person);
            }
        }
    }
    
    return new PersonRoot { People = personList };
}

// 使用示例
string studentJson = @"{""Students"": [{""FirstName"":""Abc"",""LastName"":""pqr""},{""FirstName"":""pqr"",""LastName"":""pqccr""}]}";
string employeeJson = @"{""Employee"": [{""FName"":""Abc"",""LName"":""pqr""},{""FName"":""pqr"",""LName"":""pqccr""}]}";

var studentPerson = ConvertToPersonJson(studentJson);
var employeePerson = ConvertToPersonJson(employeeJson);

// 序列化输出目标JSON
string targetJson = JsonSerializer.Serialize(studentPerson, new JsonSerializerOptions { WriteIndented = true });
Console.WriteLine(targetJson);

方案二：基于强类型模型的转换 #

如果供应商的JSON结构稳定，这种方法类型更安全：

using System.Text.Json;
using System.Text.Json.Serialization;

// 目标通用模型
public class Person
{
    [JsonPropertyName("First_Name")]
    public string FirstName { get; set; }
    
    [JsonPropertyName("Last_Name")]
    public string LastName { get; set; }
}

public class PersonRoot
{
    [JsonPropertyName("Person")]
    public List<Person> People { get; set; }
}

// 定义供应商输入模型
public class Student
{
    [JsonPropertyName("FirstName")]
    public string FirstName { get; set; }
    
    [JsonPropertyName("LastName")]
    public string LastName { get; set; }
}

public class StudentRoot
{
    [JsonPropertyName("Students")]
    public List<Student> Students { get; set; }
}

public class Employee
{
    [JsonPropertyName("FName")]
    public string FirstName { get; set; }
    
    [JsonPropertyName("LName")]
    public string LastName { get; set; }
}

public class EmployeeRoot
{
    [JsonPropertyName("Employee")]
    public List<Employee> Employees { get; set; }
}

public static PersonRoot ConvertToPersonJson(string vendorJson)
{
    PersonRoot result = new PersonRoot { People = new List<Person>() };
    
    // 先尝试反序列化为学生模型
    try
    {
        var studentRoot = JsonSerializer.Deserialize<StudentRoot>(vendorJson);
        if (studentRoot?.Students != null)
        {
            result.People.AddRange(studentRoot.Students.Select(s => new Person 
            { 
                FirstName = s.FirstName, 
                LastName = s.LastName 
            }));
            return result;
        }
    }
    catch (JsonException)
    {
        // 不是学生JSON，继续尝试员工模型
    }
    
    // 尝试反序列化为员工模型
    try
    {
        var employeeRoot = JsonSerializer.Deserialize<EmployeeRoot>(vendorJson);
        if (employeeRoot?.Employees != null)
        {
            result.People.AddRange(employeeRoot.Employees.Select(e => new Person 
            { 
                FirstName = e.FirstName, 
                LastName = e.LastName 
            }));
            return result;
        }
    }
    catch (JsonException)
    {
        throw new InvalidOperationException("输入JSON不符合学生或员工结构");
    }
    
    return result;
}

// 使用示例
string studentJson = @"{""Students"": [{""FirstName"":""Abc"",""LastName"":""pqr""},{""FirstName"":""pqr"",""LastName"":""pqccr""}]}";
var targetJson = JsonSerializer.Serialize(ConvertToPersonJson(studentJson), new JsonSerializerOptions { WriteIndented = true });
Console.WriteLine(targetJson);

注意事项 #

• 两种方案都支持WriteIndented选项来生成格式化的JSON，和你示例中的格式一致。
• 如果后续有更多供应商结构，只需在映射逻辑中添加对应的字段判断（方案一）或新增输入模型（方案二）即可扩展。

内容的提问来源于stack exchange，提问作者Prasad Gavande