摘要:學習筆記:Ch6實作PageStatePersister 來壓縮ViewState
1.壓縮方法
public class CompressHelp 
{ 
//序列化工具，LosFormatter是頁面預設的序列器 private static LosFormatter _formatter = new LosFormatter(); 
/// <summary> 
/// 解壓並反序列化狀態內容 /// </summary> /// <param name="stateString">從用戶端取回的頁面狀態字串</param> 
/// <returns>還原後的頁面狀態Pair物件</returns> public static object Decompress(string stateString) { byte[] buffer = Convert.FromBase64String(stateString); MemoryStream ms = new MemoryStream(buffer);//將內容放作MemoryStream GZipStream zipStream = new GZipStream(ms, CompressionMode.Decompress);//解壓 MemoryStream msReader = new MemoryStream(); buffer = new byte[0x1000];// buffer = new byte[4096]; while (true)//將解壓內容讀入msReader { int read = zipStream.Read(buffer, 0, buffer.Length); if (read <= 0) break; msReader.Write(buffer, 0, read); } zipStream.Close(); ms.Close(); msReader.Position = 0;//設定為最前面 buffer = msReader.ToArray();//取出內容 stateString = Convert.ToBase64String(buffer);//將byte變為字串 return _formatter.Deserialize(stateString);//反序列 } /// <summary> /// 序列化並壓縮狀態資料 /// </summary> /// <param name="state">頁面狀態</param> /// <returns>結果字串</returns> public static string Compress(object state) { StringWriter writer = new StringWriter(); _formatter.Serialize(writer, state); string stateString = writer.ToString(); byte[] buffer = Convert.FromBase64String(stateString); //將壓縮內容寫入ms MemoryStream ms = new MemoryStream(); GZipStream zipStream = new GZipStream(ms, CompressionMode.Compress, true); zipStream.Write(buffer, 0, buffer.Length); zipStream.Close(); //將壓縮內容取出至buffer buffer = new byte[ms.Length]; ms.Position = 0; ms.Read(buffer, 0, buffer.Length); ms.Close(); //將buffer轉成base64字串 stateString = Convert.ToBase64String(buffer); return stateString; } 
}
2.實作PageStatePersister
/// <summary> /// 實作PageStatePersister 來壓縮ViewState /// </summary> public class CompressPageStatePersister : PageStatePersister { //頁面狀態鍵值 private string PageStateKey = "____VIEWSTATE"; public CompressPageStatePersister(Page page) : base(page) { } public override void Load() { //取得頁面狀態鍵值 string postbackState = Page.Request.Form[PageStateKey]; if (string.IsNullOrEmpty(postbackState)) return; //頁面狀態包括視圖狀態和控制項狀態兩部分 Pair statePair = (Pair)CompressHelp.Decompress(postbackState); if(!Page.EnableViewState) this.ViewState=null; else ViewState = statePair.First;//視圖狀態 this.ControlState = statePair.Second;//控制項狀態 } public override void Save() { if (!Page.EnableViewState) this.ViewState = null; if (this.ViewState != null || this.ControlState != null) { Pair statePair = new Pair(ViewState, ControlState);//將頁面狀態及控制項狀態存到Pair string stateString = CompressHelp.Compress(statePair);//壓縮物件並序列化成字串 Page.ClientScript.RegisterHiddenField(PageStateKey, stateString);//存在隱藏欄位 } } }
3.使用方式
public partial class CompressPageState : System.Web.UI.Page { protected override PageStatePersister PageStatePersister { get { return new CompressPageStatePersister(this); } } protected void Page_Load(object sender, EventArgs e) { } protected void btnShow_Click(object sender, EventArgs e) { this.lblMsg.Text = ""; for (int i = 0; i < 1000; i++) { this.lblMsg.Text += DateTime.Now.ToShortTimeString() + " OK:" + this.ViewStateControl1.FaceStyle.OK + "<br>"; } } }