有时候为了提升WebAPI的性能,减少响应时间,我们会使用压缩和解压,而现在大多数客户端浏览器都提供了内置的解压支持。在WebAPI请求的资源越大时,使用压缩对性能提升的效果越明显,而当请求的资源很小时则不需要使用压缩和解压,因为压缩和解压同样也是需要耗费一定的时间的。
看见老外写了一篇ASP.NET Web API GZip compression ActionFilter with 8 lines of code
说实话被这标题吸引了,8行代码实现GZip压缩过滤器,我就照着他的去实践了一番,发现居然中文出现乱码。
按照他的实现方式:
1、下载DotNetZipLib库
2、解压后添加Ionic.Zlib.dll的dll引用
3、新建DeflateCompression特性和GZipCompression特性,分别代表Deflate压缩和GZip压缩,这两种压缩方式的实现代码很相似
不同的地方就是
actContext.Response.Content.Headers.Add("Content-encoding", "gzip");
actContext.Response.Content.Headers.Add("Content-encoding", "deflate");
和
var compressor = new DeflateStream( output, CompressionMode.Compress, CompressionLevel.BestSpeed)
var compressor = new GZipStream( output, CompressionMode.Compress, CompressionLevel.BestSpeed)
using System.Net.Http; using System.Web.Http.Filters; namespace WebAPI.Filter { public class GZipCompressionAttribute : ActionFilterAttribute { public override void OnActionExecuted(HttpActionExecutedContext actContext) { var content = actContext.Response.Content; var bytes = content == null ? null : content.ReadAsByteArrayAsync().Result; var zlibbedContent = bytes == null ? new byte[0] : CompressionHelper.GZipByte(bytes); actContext.Response.Content = new ByteArrayContent(zlibbedContent); actContext.Response.Content.Headers.Remove("Content-Type"); actContext.Response.Content.Headers.Add("Content-encoding", "gzip"); actContext.Response.Content.Headers.Add("Content-Type", "application/json"); base.OnActionExecuted(actContext); } } } using System.Net.Http; using System.Web.Http.Filters; namespace WebAPI.Filter { public class DeflateCompressionAttribute : ActionFilterAttribute { public override void OnActionExecuted(HttpActionExecutedContext actContext) { var content = actContext.Response.Content; var bytes = content == null ? null : content.ReadAsByteArrayAsync().Result; var zlibbedContent = bytes == null ? new byte[0] : CompressionHelper.DeflateByte(bytes); actContext.Response.Content = new ByteArrayContent(zlibbedContent); actContext.Response.Content.Headers.Remove("Content-Type"); actContext.Response.Content.Headers.Add("Content-encoding", "deflate"); actContext.Response.Content.Headers.Add("Content-Type", "application/json"); base.OnActionExecuted(actContext); } }
4、添加一个压缩帮助类CompressionHelper
using System.IO; using Ionic.Zlib; namespace WebAPI.Filter { public class CompressionHelper { public static byte[] DeflateByte(byte[] str) { if (str == null) { return null; } using (var output = new MemoryStream()) { using ( var compressor = new DeflateStream( output, CompressionMode.Compress, CompressionLevel.BestSpeed)) { compressor.Write(str, 0, str.Length); } return output.ToArray(); } } public static byte[] GZipByte(byte[] str) { if (str == null) { return null; } using (var output = new MemoryStream()) { using ( var compressor = new GZipStream( output, CompressionMode.Compress, CompressionLevel.BestSpeed)) { compressor.Write(str, 0, str.Length); } return output.ToArray(); } } } }
5、控制器调用,这里我写的测试代码:
public class TestController : ApiController { StringBuilder sb = new StringBuilder(); [GZipCompression] public string Get(int id) { for (int i = 0; i < 1000;i++ ) { sb.Append("这里是中国的领土" + i); } return sb.ToString() + DateTime.Now.ToLocalTime() + "," + id; } }
先看下不使用压缩,注释//[GZipCompression] 标记,文件大小是26.4kb,请求时间是1.27s
使用[GZipCompression]标记,添加压缩后,文件大小是2.4kb,响应时间是1.21,Respouse Body明显小了很多,但是响应时间少得并不明显,因为在本地环境下载太快了,而压缩解压却要消耗一定的时间,界面加载的时间主要消耗在onload上了。有个问题:中文显示乱码了。
使用.net自带的压缩,在System.IO.Compression中提供了对应的类库——GZipStream与DeflateStream。控制器调用代码不变,新建一个CompressContentAttribute.cs类,代码如下:
using System.Web; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace WebAPI.Filter { // <summary> /// 自动识别客户端是否支持压缩,如果支持则返回压缩后的数据 /// Attribute that can be added to controller methods to force content /// to be GZip encoded if the client supports it /// </summary> public class CompressContentAttribute : ActionFilterAttribute { /// <summary> /// Override to compress the content that is generated by /// an action method. /// </summary> /// <param name="filterContext"></param> public override void OnActionExecuting(HttpActionContext filterContext) { GZipEncodePage(); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("deflate")) { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); #region II6不支持此方法,(实际上此值默认为null 也不需要移除) //Response.Headers.Remove("Content-Encoding"); #endregion Response.AppendHeader("Content-Encoding", "deflate"); } else { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); #region II6不支持此方法,(实际上此值默认为null 也不需要移除) //Response.Headers.Remove("Content-Encoding"); #endregion Response.AppendHeader("Content-Encoding", "gzip"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } } /// <summary> /// 强制Defalte压缩 /// Content-encoding:gzip,Content-Type:application/json /// DEFLATE是一个无专利的压缩算法,它可以实现无损数据压缩,有众多开源的实现算法。 /// </summary> public class DeflateCompressionAttribute : ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext filterContext) { HttpResponse Response = HttpContext.Current.Response; Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); #region II6不支持此方法,(实际上此值默认为null 也不需要移除) //Response.Headers.Remove("Content-Encoding"); #endregion Response.AppendHeader("Content-Encoding", "deflate"); } } /// <summary> /// 强制GZip压缩,application/json /// Content-encoding:gzip,Content-Type:application/json /// GZIP是使用DEFLATE进行压缩数据的另一个压缩库 /// </summary> public class GZipCompressionAttribute : ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext filterContext) { HttpResponse Response = HttpContext.Current.Response; Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); #region II6不支持此方法,(实际上此值默认为null 也不需要移除) //Response.Headers.Remove("Content-Encoding"); #endregion Response.AppendHeader("Content-Encoding", "gzip"); } } }
运行查看结果,压缩能力比DotNetZipLib略差,但是不再出现乱码了。
把控制器代码中的标记改为 [DeflateCompression],使用Deflate压缩再来看下效果:
Deflate压缩后,Content-Length值为2538,而GZip压缩Content-Length值为2556,可见Deflate压缩效果更好。
这里,WebAPI的压缩我都是通过Action过滤器的方式来实现,当然你也可以写在WebAPI中的全局配置中,考虑到有些API接口并不需要使用到压缩,所以就通过Action过滤器的方式来实现了。
dudu的这篇文章HttpClient与APS.NET Web API:请求内容的压缩与解压在客户端压缩、在服务端解压。
原文地址:https://www.cnblogs.com/lhxsoft/p/8663637.html