add(refreshTokenService)：完善刷新令牌服务

backend/IM_API/Services/FriendService.cs

@@ -1,6 +1,10 @@
-namespace IM_API.Services
+using IM_API.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace IM_API.Services
 {
     public class FriendService
     {
+        
     }
 }

backend/IM_API/Services/JWTService.cs

@@ -0,0 +1,55 @@
+using IM_API.Interface.Services;
+using Microsoft.IdentityModel.Tokens;
+using System.IdentityModel.Tokens.Jwt;
+using System.Security.Claims;
+using System.Text;
+
+namespace IM_API.Services
+{
+    public class JWTService : IJWTService
+    {
+        private readonly IConfiguration _config;
+        private readonly string _key;
+        private readonly string _issuer;
+        private readonly string _audience;
+        private readonly int _accessMinutes;
+
+        public JWTService(IConfiguration config)
+        {
+            _config = config;
+            _key = _config["Jwt:Key"]!;
+            _issuer = _config["Jwt:Issuer"]!;
+            _audience = _config["Jwt:Audience"]!;
+            _accessMinutes = int.Parse(_config["Jwt:AccessTokenMinutes"] ?? "15");
+        }
+
+        public string GenerateAccessToken(IEnumerable<Claim> claims, DateTime expiresAt)
+        {
+            var keyBytes = Encoding.UTF8.GetBytes(_key);
+            var creds = new SigningCredentials(new SymmetricSecurityKey(keyBytes), SecurityAlgorithms.HmacSha256);
+
+            var token = new JwtSecurityToken(
+                issuer: _issuer,
+                audience: _audience,
+                claims: claims,
+                expires: expiresAt,
+                signingCredentials: creds
+            );
+
+            return new JwtSecurityTokenHandler().WriteToken(token);
+        }
+
+        public (string token, DateTime expiresAt) CreateAccessTokenForUser(int userId, string username, string role)
+        {
+            var expiresAt = DateTime.UtcNow.AddMinutes(_accessMinutes);
+            var claims = new[]
+            {
+                new Claim(JwtRegisteredClaimNames.Sub, userId.ToString()),
+                new Claim(ClaimTypes.Name, username),
+                new Claim(ClaimTypes.Role, role)
+            };
+            var token = GenerateAccessToken(claims, expiresAt);
+            return (token, expiresAt);
+        }
+    }
+}

backend/IM_API/Services/RedisRefreshTokenService.cs

@@ -0,0 +1,66 @@
+using IM_API.Interface.Services;
+using Microsoft.AspNetCore.Connections;
+using Newtonsoft.Json;
+using StackExchange.Redis;
+using System.Numerics;
+using System.Security.Cryptography;
+using System.Text.Json;
+
+namespace IM_API.Services
+{
+    public class RedisRefreshTokenService : IRefreshTokenService
+    {
+        private readonly ILogger<RedisRefreshTokenService> _logger;
+        //redis数据库
+        private readonly IDatabase _db;
+        private IConfiguration configuration;
+        //过期时长
+        private readonly TimeSpan _refreshTTL;
+        public RedisRefreshTokenService(ILogger<RedisRefreshTokenService> logger, IConnectionMultiplexer multiplexer, IConfiguration configuration)
+        {
+            _logger = logger;
+            _db = multiplexer.GetDatabase();
+            this.configuration = configuration;
+            //设置refresh过期时间
+            var days = int.Parse(this.configuration["Jwt:RefreshTokenDays"] ?? "30");
+            _refreshTTL = TimeSpan.FromDays(days);
+        }
+
+        private static string GenerateTokenStr()
+        {
+            var bytes = RandomNumberGenerator.GetBytes(32);
+            return Convert.ToBase64String(bytes);
+        }
+
+        public async Task<string> CreateRefreshTokenAsync(int userId, CancellationToken ct = default)
+        {
+            string token = GenerateTokenStr();
+            var payload = new { UserId = userId,CreateAt = DateTime.Now};
+            string json = JsonConvert.SerializeObject(payload);
+            //token写入redis
+            await _db.StringSetAsync(token,json,_refreshTTL);
+            return token;
+        }
+
+        public async Task RevokeRefreshTokenAsync(string token, CancellationToken ct = default)
+        {
+            await _db.KeyDeleteAsync(token);
+        }
+
+        public async Task<(bool ok, int userId)> ValidateRefreshTokenAsync(string token, CancellationToken ct = default)
+        {
+            var json = await _db.StringGetAsync(token);
+            if (json.IsNullOrEmpty) return (false,-1);
+            try
+            {
+                var doc = JsonConvert.DeserializeObject<JsonElement>(json);
+                var userId = doc.GetProperty("UserId").GetInt32();
+                return (true,userId);
+            }
+            catch
+            {
+                return (false,-1);
+            }
+        }
+    }
+}