Skip to content

WebView2ResponseHeaders.md

Latest commit

 

History

History
297 lines (215 loc) · 8.86 KB

WebView2ResponseHeaders.md

File metadata and controls

297 lines (215 loc) · 8.86 KB
Raw
title ResponseHeaders
parent WebView2 Package
nav_order 13

WebView2ResponseHeaders Class

The WebView2ResponseHeaders class is used to manage HTTP response header information, primarily used to build custom responses in the WebResourceRequested event.

Class Information

Property Value
Class Name WebView2ResponseHeaders
COM Creatable No

Methods

AppendHeader

Public Sub AppendHeader(ByVal name As String, ByVal value As String)

Adds a response header (allows multiple values with the same name).

Parameters:

  • name - Response header name
  • value - Response header value

Example:

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Set basic response headers
    Response.Headers.AppendHeader "Content-Type", "application/json"
    Response.Headers.AppendHeader "Cache-Control", "no-cache"
    Response.Headers.AppendHeader "Access-Control-Allow-Origin", "*"
End Sub

Contains

Public Function Contains(ByVal name As String) As Boolean

Checks if a response header with the specified name exists.

Parameters:

  • name - Response header name

Return Value: Returns True if it contains, otherwise returns False

Example:

If Response.Headers.Contains("Content-Type") Then
    Debug.Print "Response contains Content-Type header"
End If

GetHeader

Public Function GetHeader(ByVal name As String) As String

Gets the first value of the response header with the specified name.

Parameters:

  • name - Response header name

Return Value: The value string of the response header

Example:

Dim contentType As String
contentType = Response.Headers.GetHeader("Content-Type")

GetHeaders

Public Function GetHeaders(ByVal name As String) As WebView2HeadersCollection

Gets all values of the response header with the specified name.

Parameters:

  • name - Response header name

Return Value: WebView2HeadersCollection collection object

Enumerator

Public Function _NewEnum() As WebView2HeadersCollection

Supports For Each to enumerate all response headers.

Example:

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    Debug.Print "Setting response headers:"
    Response.Headers.AppendHeader "Content-Type", "text/html"
    Response.Headers.AppendHeader "Cache-Control", "max-age=3600"
    Response.Headers.AppendHeader "Server", "MyServer/1.0"

    Dim header As WebView2Header
    For Each header In Response.Headers
        Debug.Print "  " & header.Name & ": " & header.Value
    Next
End Sub

Usage Scenarios

1. Build Custom Response

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Set HTML response
    Response.StatusCode = 200
    Response.ReasonPhrase = "OK"
    Response.ContentUTF8 = "<html><body><h1>Interception Successful</h1></body></html>"
    Response.Headers.AppendHeader "Content-Type", "text/html; charset=utf-8"
    Response.Headers.AppendHeader "Content-Length", Len(Response.ContentUTF8)
End Sub

2. Return JSON Data

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Build response headers
    Response.StatusCode = 200
    Response.ReasonPhrase = "OK"
    Response.ContentUTF8 = "{""status"":""success"",""data"":""hello""}"

    ' Set JSON response headers
    Response.Headers.AppendHeader "Content-Type", "application/json"
    Response.Headers.AppendHeader "Access-Control-Allow-Origin", "*"
    Response.Headers.AppendHeader "Cache-Control", "no-store"
End Sub

3. Intercept Image Requests

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Check if it's an image request
    If InStr(Request.Uri, ".png") > 0 Or InStr(Request.Uri, ".jpg") > 0 Then
        ' Return placeholder image
        Response.StatusCode = 200
        Response.ReasonPhrase = "OK"
        Response.ContentUTF8 = "<svg xmlns='http://www.w3.org/2000/svg' width='100' height='100'><rect width='100' height='100' fill='gray'/></svg>"
        Response.Headers.AppendHeader "Content-Type", "image/svg+xml"
    End If
End Sub

4. Simulate API Response

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Intercept specific API requests
    If InStr(Request.Uri, "/api/user") > 0 Then
        Dim jsonData As String
        jsonData = "{""id"":1,""name"":""张三"",""email"":""zhangsan@example.com""}"

        Response.StatusCode = 200
        Response.ReasonPhrase = "OK"
        Response.ContentUTF8 = jsonData

        ' Set complete API response headers
        Response.Headers.AppendHeader "Content-Type", "application/json"
        Response.Headers.AppendHeader "Access-Control-Allow-Origin", "*"
        Response.Headers.AppendHeader "Access-Control-Allow-Methods", "GET, POST, OPTIONS"
        Response.Headers.AppendHeader "Access-Control-Allow-Headers", "Content-Type"
        Response.Headers.AppendHeader "X-Request-ID", CStr(Timer))
    End If
End Sub

5. Return Error Response

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Intercept unauthorized access
    If InStr(Request.Uri, "/admin/") > 0 Then
        Dim errorHtml As String
        errorHtml = "<html><body><h1>403 Forbidden</h1><p>No permission to access this resource</p></body></html>"

        Response.StatusCode = 403
        Response.ReasonPhrase = "Forbidden"
        Response.ContentUTF8 = errorHtml
        Response.Headers.AppendHeader "Content-Type", "text/html; charset=utf-8"
        Response.Headers.AppendHeader "X-Error-Reason", "Unauthorized"
    End If
End Sub

6. Set Cache Policy

Private Sub WebView21_WebResourceRequested(ByVal Request As WebView2Request, _
    ByVal Response As WebView2Response)

    ' Set different cache policies based on resource type
    If InStr(Request.Uri, ".css") > 0 Or InStr(Request.Uri, ".js") > 0 Then
        ' Long-term caching for static resources
        Response.Headers.AppendHeader "Cache-Control", "public, max-age=31536000"
        Response.Headers.AppendHeader "Expires", "Sat, 31 Dec 2030 23:59:59 GMT"
    Else
        ' No caching for dynamic content
        Response.Headers.AppendHeader "Cache-Control", "no-cache, no-store, must-revalidate"
        Response.Headers.AppendHeader "Pragma", "no-cache"
        Response.Headers.AppendHeader "Expires", "0"
    End If
End Sub

Common Response Headers

Content Types

Response.Headers.AppendHeader "Content-Type", "text/html; charset=utf-8"
Response.Headers.AppendHeader "Content-Type", "application/json"
Response.Headers.AppendHeader "Content-Type", "image/jpeg"
Response.Headers.AppendHeader "Content-Type", "application/pdf"
Response.Headers.AppendHeader "Content-Type", "application/octet-stream"

CORS Control

Response.Headers.AppendHeader "Access-Control-Allow-Origin", "*"
Response.Headers.AppendHeader "Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS"
Response.Headers.AppendHeader "Access-Control-Allow-Headers", "Content-Type, Authorization"

Cache Control

Response.Headers.AppendHeader "Cache-Control", "no-cache"
Response.Headers.AppendHeader "Cache-Control", "public, max-age=3600"
Response.Headers.AppendHeader "Cache-Control", "no-store"

Security Headers

Response.Headers.AppendHeader "X-Content-Type-Options", "nosniff"
Response.Headers.AppendHeader "X-Frame-Options", "DENY"
Response.Headers.AppendHeader "X-XSS-Protection", "1; mode=block"
Response.Headers.AppendHeader "Strict-Transport-Security", "max-age=31536000"

Notes

  1. Character Encoding: The Content-Type header should specify the correct character set, such as text/html; charset=utf-8.

  2. CORS Issues: For cross-origin requests, need to set the correct Access-Control-Allow-Origin header.

  3. Content Length: If setting Content-Length header, ensure the value matches the actual content length.

  4. Security: When setting custom responses, pay attention to avoid security vulnerabilities, such as XSS attacks.

  5. Performance Considerations: For frequently intercepted resources, ensure the response building logic is efficient to avoid blocking the main thread.

  6. Response Integrity: Ensure to set StatusCode, ReasonPhrase, and Content simultaneously, otherwise the response may be incomplete.

  7. Special Header Handling: Some response headers (such as Content-Length) may be automatically handled by WebView2, manual setting may be ignored.