javascript – 下载WKWebView中加载的嵌入式PDF

从url加载HTML5页面时,我在该页面的某处获得了pdf,我必须下载该pdf或将其保存为base64.

这是pdf在HTML代码中的位置.我不能简单地点击’src’网址并获得pdf.

< embed width="100%" height="100%" name="plugin" id="plugin" src="https://myurl.com/fileToOpen.pdf” type="application/pdf" internalinstanceid="8" title="">

任何JS可以帮助我获得base64字符串或任何其他方法下载？

解决方法:

更新

他们说从Docs开始

The Fetch API provides an interface for fetching resources (including
across the network). It will seem familiar to anyone who has used
XMLHttpRequest

您还可以使用以下字符串从WKWebview获取base64字符串

 let s = "path = document.getElementById(\"plugin\").src\n" +
        "\n" +
        "fetch(path).then(function (response) {\n" +
        " response.body.getReader().read().then(function(result) {\n" +
        " return btoa(String.fromCharCode.apply(null, result.value));\n" +
        " }).then(function(b64) {\n" +
        " window.webkit.messageHandlers.myInterface.postMessage(b64);\n" +
        " });\n" +
        "});"

fetch和xmlhttp都工作异步..所有你需要做的就是等待处理完成后使用javascript的桥接器将其传递给Swift(WKScriptMessageHandler)

使用以下代码从javascript到Swift获取base64字符串.
当base64字符串准备好被使用时,我正在使用WKScriptMessageHandler从Javascript获取回调.在String中,您只需要传递pdf的url,它将执行ajax请求以获取pdf文件,然后将其转换为base64字符串.

import UIKit
import WebKit
class ViewController: UIViewController {
    @IBOutlet weak var btnPDF: UIButton!
    @IBOutlet weak var webViewParentView: UIView!
    var activityIndicator: UIActivityIndicatorView?
    var webView: WKWebView!
    @objc func didSelect(_ sender: UIView){
        let s="var xhr = new XMLHttpRequest();\n" +
            "xhr.open(\'GET\', \"https://codingexceptions.com/wkwebview/dummy.pdf\", true);\n" +
            "\n" +
            "xhr.responseType = \'arraybuffer\';\n" +
            "\n" +
            "xhr.onload = function(e) {\n" +
            " if (this.status == 200) {\n" +
            " var uInt8Array = new Uint8Array(this.response);\n" +
            " var i = uInt8Array.length;\n" +
            " var binaryString = new Array(i);\n" +
            " while (i--)\n" +
            " {\n" +
            " binaryString[i] = String.fromCharCode(uInt8Array[i]);\n" +
            " }\n" +
            " var data = binaryString.join(\'\');\n" +
            "\n" +
            " var base64 = window.btoa(data);\n" +
            "\n" +
            "window.webkit.messageHandlers.myInterface.postMessage(base64);" +
            "\n" +
            " }\n" +
            "};\n" +
            "\n" +
        "xhr.send();\n"
        webView.configuration.userContentController.add(self, name: "myInterface")
        webView?.evaluateJavaScript(s, completionHandler: {(string,error) in
            print(error ?? "no error")
        })
    }
    func setupWebView(){
        webView = WKWebView.init(frame: CGRect(x: 0, y: 0, width: webViewParentView.frame.width, height: webViewParentView.frame.height))
        webView.navigationDelegate = self
        webViewParentView.addSubview(webView)
        activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
        activityIndicator?.center = self.view.center
        self.view.addSubview(activityIndicator!)
        webView.load(URLRequest(url: URL(string: "https://codingexceptions.com/wkwebview/index.php")!))
        activityIndicator?.startAnimating()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        btnPDF.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)

    }
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
         setupWebView()
    }
}
extension ViewController: WKScriptMessageHandler{
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
         print("Message received: \(message.name) with body: \(message.body)")
    }
}
extension ViewController: WKNavigationDelegate{
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        self.activityIndicator?.stopAnimating()
        self.activityIndicator?.removeFromSuperview()
        self.activityIndicator = nil
    }
}

更新：从@Tarun的答案中指出,从embed标签获取源代码

只需将下面的行放在字符串变量s的开头,然后在xhr.open中传递url

var url = document.getElementById("plugin").src

原文地址：https://codeday.me/bug/20190522/1153232.html