Asp.net core可以监视json、xml等配置文件的变化, 自动刷新内存中的配置内容, 但如果想每隔1秒从zookeeper、consul获取最新的配置信息, 需要自己实现.
阅读了 Asp.net core Document的, 得知只需要实现自己的IConfigurationSource和对应ConfigurationProvider即可
在这个示例中, 我建立了一个简单的option, 只包含一个不断变化的计数器变量.
public class RefreshableOptions { public int IncreasementCount { get; set; } }
实现IConfigurationSource和对应ConfigurationProvider, 内部有一个timer模拟从外部获取了最新的数据, 这里为简单起见, 采用硬编码的方式指定了option的路径
public class AutoRefreshConfigurationSource : IConfigurationSource { public IConfigurationProvider Build(IConfigurationBuilder builder) { return new AutoRefreshConfigurationProvider(); } } public class AutoRefreshConfigurationProvider : ConfigurationProvider { private int count = 0; private bool isChanged; public AutoRefreshConfigurationProvider() : base() { Timer timer = new Timer(TimerCallback); timer.Change(1000, 3000); } public override void Load() { var beforeData = Data; // 这里采用硬编码指定option的路径 Data = new Dictionary<string, string>() { { "AutoRefreshOptions:IncreasementCount", count.ToString() } }; isChanged = IsDictionaryChanged(beforeData, Data); } private void TimerCallback(object state) { count++; this.Load(); if (isChanged) { base.OnReload();//通知IConfiguration实例, 有参数发生了改变 isChanged = false; } } //判断两个Idictionary是否有不同的帮助方法 private static bool IsDictionaryChanged(IDictionary<string, string> before, IDictionary<string, string> after) { if (before == null && after == null) { return false; } if ((before == null) != (after == null)) { return true; } if (before.Count != after.Count) { return true; } var ignoreCaseBefore = new Dictionary<string, string>(before, StringComparer.OrdinalIgnoreCase); foreach (var afterItemKey in after.Keys) { if (!ignoreCaseBefore.TryGetValue(afterItemKey, out var beforeItemValue)) { return true; } if (beforeItemValue != after[afterItemKey]) { return true; } ignoreCaseBefore.Remove(afterItemKey); } if (ignoreCaseBefore.Count > 0) { return true; } return false; } }
实现扩展方法
public static class AutoRereshConfigurationExtensions { public static IConfigurationBuilder AddAutoRereshConfiguration(this IConfigurationBuilder builder) { return builder.Add(new AutoRefreshConfigurationSource()); } }
使用方法
新建一个WebApi项目, 在Program.CreateWebHostBuilder中增加黄色部分
WebHost.CreateDefaultBuilder(args) .ConfigureAppConfiguration(config => { config.AddAutoRereshConfiguration(); }) .UseStartup<Startup>();
在Startup. ConfigureServices中配置
services.Configure<RefreshableOptions>(Configuration.GetSection("AutoRefreshOptions"));
修改ValuesController
[Route("api/[controller]")] [ApiController] public class ValuesController : ControllerBase { private RefreshableOptions refreshableOptions; public ValuesController(IOptionsSnapshot<RefreshableOptions> refreshableOptions) { this.refreshableOptions = refreshableOptions.Value; } [HttpGet] public ActionResult<IEnumerable<string>> Get() { return new string[] { "value1", "value2", refreshableOptions.IncreasementCount.ToString() }; } }
启动后不停的刷新:5000/api/values可以看到返回内容的变化