为何存在JwtSecurityTokenHandler与JsonWebTokenHandler两类JWT令牌处理类？

Great question—this confusion is totally common given how similar their namespaces and core purpose are. Let’s break down the key differences, use cases, and which one you should pick:

Core Differences #

First, let’s clarify their origins:

• JwtSecurityTokenHandler lives in the System.IdentityModel.Tokens.Jwt namespace, part of the older Microsoft.IdentityModel.Tokens.Jwt NuGet package. It’s rooted in the legacy Windows Identity Foundation (WIF) ecosystem, designed to handle not just JWTs but other token formats too.
• JsonWebTokenHandler is in the Microsoft.IdentityModel.JsonWebTokens namespace, from the newer, focused Microsoft.IdentityModel.JsonWebTokens package. It’s built specifically for JWTs, with a cleaner, more modern API.

The big one you pointed out is the return type of ValidateToken:

• JwtSecurityTokenHandler.ValidateToken() returns a ClaimsPrincipal (plus an out parameter for the token). To get JWT-specific details (like raw header/payload, expiration time, issuer), you have to cast the token to JwtSecurityToken manually.
• JsonWebTokenHandler.ValidateToken() returns a TokenValidationResult that includes both the ClaimsPrincipal and a JsonWebToken instance. This gives you direct access to all JWT-native properties without extra parsing—way more convenient if you need to work with the token itself beyond just claims.

Other notable distinctions:

• API Focus: JsonWebTokenHandler has a streamlined API dedicated to JWT operations (parsing, validation, writing). JwtSecurityTokenHandler carries over compatibility code for older token systems, making it a bit heavier.
• Package Size: The Microsoft.IdentityModel.JsonWebTokens package has fewer dependencies, so it’s a lighter footprint for projects that only need JWT support.

When to Use Which #

• Prefer JsonWebTokenHandler if:
  • You’re building a new project (especially ASP.NET Core 3.0+).
  • You only need to handle JWT tokens (no legacy formats like SAML).
  • You want easy access to raw JWT data (header, payload, token string) alongside the claims principal.
• Stick with JwtSecurityTokenHandler if:
  • Your project relies on legacy WIF/WS-Federation components.
  • You need to validate or process non-JWT token formats.
  • You’re maintaining an older codebase that already uses it extensively.

Quick Usage Example for JsonWebTokenHandler #

Here’s a simple validation snippet to show how straightforward it is:

using Microsoft.IdentityModel.JsonWebTokens;
using Microsoft.IdentityModel.Tokens;
using System.Text;

var handler = new JsonWebTokenHandler();
var validationParams = new TokenValidationParameters
{
    ValidateIssuer = true,
    ValidIssuer = "https://your-issuer.com",
    ValidateAudience = true,
    ValidAudience = "your-audience",
    ValidateLifetime = true,
    IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("your-secure-signing-key"))
};

try
{
    var validationResult = handler.ValidateToken("your-jwt-token-string", validationParams);
    
    // Access JWT-specific properties directly
    var jwt = validationResult.SecurityToken as JsonWebToken;
    Console.WriteLine($"Token expires at: {jwt.ExpirationTime}");
    Console.WriteLine($"Raw token header: {jwt.RawHeader}");
    
    // Use the claims principal as usual
    var user = validationResult.ClaimsPrincipal;
}
catch (SecurityTokenException ex)
{
    Console.WriteLine($"Token validation failed: {ex.Message}");
}

Microsoft’s official guidance leans toward JsonWebTokenHandler for modern JWT scenarios—it’s the more focused, future-proof choice.

内容的提问来源于stack exchange，提问作者hemant