Class (WebSchemeHandler)

Represents a WebSchemeHandler object used to intercept requests for a specific scheme.

NOTE

The initial APIs of this module are supported since API version 9. Updates will be marked with a superscript to indicate their earliest API version.

The initial APIs of this class are supported since API version 12.

The sample effect is subject to the actual device.

Module to Import

import { webview } from '@kit.ArkWeb';

onRequestStart¹²⁺

onRequestStart(callback: (request: WebSchemeHandlerRequest, handler: WebResourceHandler) => boolean): void

Called when a request starts. In this callback, you can determine whether to intercept the request. If false is returned, the request is not intercepted and the handler is invalid. If true is returned, the request is intercepted.

System capability: SystemCapability.Web.Webview.Core

Parameters

Name	Type	Mandatory	Description
callback	(request: WebSchemeHandlerRequest, handler: WebResourceHandler) => boolean	Yes	Callback invoked when a request for the specified scheme starts. request represents a request. handler provides the custom response header and response body for the Web component. The return value indicates whether the request is intercepted.

Error codes

For details about the error codes, see Universal Error Codes.

Error Code	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified. 2. Incorrect parameter types.

Example

// xxx.ets
import { webview, WebNetErrorList } from '@kit.ArkWeb';
import { BusinessError } from '@kit.BasicServicesKit';
import { buffer } from '@kit.ArkTS';

@Entry
@Component
struct WebComponent {
  controller: webview.WebviewController = new webview.WebviewController();
  schemeHandler: webview.WebSchemeHandler = new webview.WebSchemeHandler();
  htmlData: string = "<html><body bgcolor=\"white\">Source:<pre>source</pre></body></html>";

  build() {
    Column() {
      Web({ src: 'https://www.example.com', controller: this.controller })
        .onControllerAttached(() => {
          try {
            this.schemeHandler.onRequestStart((request: webview.WebSchemeHandlerRequest, resourceHandler: webview.WebResourceHandler) => {
              console.info("[schemeHandler] onRequestStart");
              try {
                console.info("[schemeHandler] onRequestStart url:" + request.getRequestUrl());
                console.info("[schemeHandler] onRequestStart method:" + request.getRequestMethod());
                console.info("[schemeHandler] onRequestStart referrer:" + request.getReferrer());
                console.info("[schemeHandler] onRequestStart isMainFrame:" + request.isMainFrame());
                console.info("[schemeHandler] onRequestStart hasGesture:" + request.hasGesture());
                console.info("[schemeHandler] onRequestStart header size:" + request.getHeader().length);
                console.info("[schemeHandler] onRequestStart resource type:" + request.getRequestResourceType());
                console.info("[schemeHandler] onRequestStart frame url:" + request.getFrameUrl());
                let header = request.getHeader();
                for (let i = 0; i < header.length; i++) {
                  console.info("[schemeHandler] onRequestStart header:" + header[i].headerKey + " " + header[i].headerValue);
                }
                let stream = request.getHttpBodyStream();
                if (stream) {
                  console.info("[schemeHandler] onRequestStart has http body stream");
                } else {
                  console.info("[schemeHandler] onRequestStart has no http body stream");
                }
              } catch (error) {
                console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
              }

              if (request.getRequestUrl().endsWith("example.com")) {
                return false;
              }

              let response = new webview.WebSchemeHandlerResponse();
              try {
                response.setNetErrorCode(WebNetErrorList.NET_OK);
                response.setStatus(200);
                response.setStatusText("OK");
                response.setMimeType("text/html");
                response.setEncoding("utf-8");
                response.setHeaderByName("header1", "value1", false);
              } catch (error) {
                console.error(`[schemeHandler] ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
              }

              // Before calling didFinish or didFail, call didReceiveResponse to send a response header to this request.
              let buf = buffer.from(this.htmlData)
              try {
                if (buf.length == 0) {
                  console.info("[schemeHandler] length 0");
                  resourceHandler.didReceiveResponse(response);
                  // If the value of buf.length is 0 in normal cases, call resourceHandler.didFinish(). Otherwise, call resourceHandler.didFail().
                  resourceHandler.didFail(WebNetErrorList.ERR_FAILED);
                } else {
                  console.info("[schemeHandler] length 1");
                  resourceHandler.didReceiveResponse(response);
                  resourceHandler.didReceiveResponseBody(buf.buffer);
                  resourceHandler.didFinish();
                }
              } catch (error) {
                console.error(`[schemeHandler] ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
              }
              return true;
            })

            this.schemeHandler.onRequestStop((request: webview.WebSchemeHandlerRequest) => {
              console.info("[schemeHandler] onRequestStop");
            });

            this.controller.setWebSchemeHandler('https', this.schemeHandler);
          } catch (error) {
            console.error(`ErrorCode: ${(error as BusinessError).code},  Message: ${(error as BusinessError).message}`);
          }
        })
        .javaScriptAccess(true)
        .domStorageAccess(true)
    }
  }
}

onRequestStop¹²⁺

onRequestStop(callback: Callback<WebSchemeHandlerRequest>): void

Called when the request is complete. This callback is triggered only when the onRequestStart callback intercepts the request. Specifically, this callback is invoked in the following cases:

The WebResourceHandler object calls didFail or didFinish.
The request is interrupted due to other reasons.