ASP.NET MVC用IHttpModule修改response的html实现压缩或者转繁体，IHttpModule用后台代码注册

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代码里面实现了html里面中文简体转繁体，用的微软自带的简繁体类库操作，效率高。在FilterStream中，Write方法里面还可以实现压缩html

实现IhttpModule操作模块

using System;
using System.Web;namespace OverrideRender.Models
{public class MyHttpModule : IHttpModule{void IHttpModule.Dispose(){//throw new NotImplementedException();}void IHttpModule.Init(HttpApplication context){context.BeginRequest += Context_BeginRequest;}private void Context_BeginRequest(object sender, EventArgs e){HttpContext.Current.Response.Filter = new FilterStream(HttpContext.Current.Response.Filter);}}
}

注册MyHttpModule，此方式注册不需要在Global.asax中注册即可生效，此类在程序注册所有Modules模块前注册到模块集合中，所以能生效

using Microsoft.Web.Infrastructure.DynamicModuleHelper;
using System.Web;[assembly: PreApplicationStartMethod(typeof(OverrideRender.Models.PreApplicationStartRegist), "PreStart")]
namespace OverrideRender.Models
{public class PreApplicationStartRegist{private static bool hasLoaded;public static void PreStart(){if (!hasLoaded){hasLoaded = true;//动态注册操作模块DynamicModuleUtility.RegisterModule(typeof(MyHttpModule));}}}
}

继承Stream，改写类，使能操作html，改写html关键类

    public class FilterStream : Stream{private Stream _sm;public FilterStream(Stream stream){_sm = stream;}public override bool CanRead{get{return true;}}public override bool CanSeek{get{return true;}}public override bool CanWrite{get{return true;}}public override long Length{get{return _sm.Length;}}public override long Position{get{return _sm.Position;}set{_sm.Position = value;}}public override void Flush(){_sm.Flush();}public override int Read(byte[] buffer, int offset, int count){return _sm.Read(buffer, offset, count);}public override long Seek(long offset, SeekOrigin origin){return _sm.Seek(offset, origin);}public override void SetLength(long value){_sm.SetLength(value);}//不用轉換的類型列表static List<string> checkTypes = new List<string>() { "jpeg", "gif", "png", "bmp", "pdf", "xlsx", "doc", "xls" };/// <summary>/// 获取到响应输出流的html文本，并修改html/// </summary>/// <param name="buffer"></param>/// <param name="offset"></param>/// <param name="count"></param>public override void Write(byte[] buffer, int offset, int count){//檢查文件類型string fileType = CheckFileType.CheckTrueFileName(buffer);if (!checkTypes.Contains(fileType)){//取得返回到浏览器的htmlstring html = Encoding.UTF8.GetString(buffer);//将html里面的简体中文转换为繁体,末尾參數設置為1033為了防止頁面亂碼產生string tHtml = Microsoft.VisualBasic.Strings.StrConv(html, VbStrConv.TraditionalChinese, 1033);              //覆盖原html，载入修改后的html   byte[] buff = Encoding.UTF8.GetBytes(tHtml);_sm.Write(buff, 0, buff.Length);}else{_sm.Write(buffer, 0, buffer.Length);}}}

检查文件真实类型

    public class CheckFileType{/// <summary>/// 檢測文件真實類型/// </summary>/// <param name="bytes"></param>/// <returns></returns>public static string CheckTrueFileName(byte[] bytes){//16進制字符string hexStr = " ";try{byte[] headBytes = bytes.Take(4).ToArray();hexStr = ByteTo16HexStr(headBytes);}catch (Exception exc){Console.WriteLine(exc.Message);}//真实的文件类型string fileName = "";FileTypeDictionary.TryGetValue(hexStr, out fileName);//Console.WriteLine(fileName);return fileName;}/// <summary>/// 將字節數組轉換為16進制字符串/// </summary>/// <param name="inputStr">傳入字節數組</param>/// <param name="encoding">16進制字符串</param>/// <returns></returns>public static string ByteTo16HexStr(byte[] buffer){StringBuilder sb = new StringBuilder();foreach (byte item in buffer){sb.AppendFormat("{0:X2}", item);}return sb.ToString();}/// <summary>/// 字節數組頭對應的文件類型/// </summary>public static Dictionary<string, string> FileTypeDictionary{get{Dictionary<string, string> dict = new Dictionary<string, string>();dict.Add("FFD8FFE0", "jpeg");dict.Add("89504E47", "png");dict.Add("47494638", "gif");dict.Add("424D424F", "bmp");dict.Add("504B0304", "zip/xlsx/docx");dict.Add("52617221", "rar");dict.Add("D0CF11E0", "xls/doc");dict.Add("25504446", "pdf");dict.Add("2F2A210D", "js");dict.Add("3C3F786D", "xml");dict.Add("7B0D0A20", "json");return dict;}}}

1028 繁體中文
1033 ASCII
2052 簡體中文
為何第二次轉換回繁體時，不用 1028 而用 1033 呢？
首先，要先知道，有些簡體中文的編碼值是在繁體中文是對應不到任何字的。此時，顯示的字就會是 "?" 號。
因為 2052 的 「 国] 已經是簡體字了，轉回到繁體時，剛好其編碼對應不到1028 的編碼，因此會是問號。
处理简体转换为繁体，页面出现乱码问题，参考地址：
https://www.cnblogs.com/fmxyw/archive/2010/02/26/1674447.html

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