无法打开使用下载管理器 API 下载的文件 android webview

Question

我正在 android 工作室的 web 视图中下载 pdf 个文件。 一切顺利。 我成功下载了一个扩展名为 .pdf 的 pdf 文件，但是当我单击该文件时，看到提示消息，出现错误无法打开此文件这是我的代码

 binding?.webView?.setDownloadListener { url, userAgent, contentDisposition, mimetype, contentLength ->
            val pdfUrl:String = url.trim().replace("blob:","")
            Log.e(TAG, "loadWAWeb:  $pdfUrl")
            if (storagePermission()) {
//                binding?.webView?.loadUrl(JavaScriptInterface.getBase64StringFromBlobUrl(url,mimetype))
                val request = DownloadManager.Request(Uri.parse(pdfUrl))
                request.setMimeType(mimetype)
                request.allowScanningByMediaScanner()
                request.setDescription("Downloading file...")
                val fileName = URLUtil.guessFileName(pdfUrl, contentDisposition, mimetype)
                request.setTitle(fileName)

                Log.e(TAG, "loadWAWeb:  $fileName" )
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName)

                val dm = getSystemService(DOWNLOAD_SERVICE) as DownloadManager
                dm.enqueue(request)

            }

        }

这是一个格式良好的 pdf 文件，但我不知道问题出在哪里。

但是当我尝试打开这个文件时。 我面临的这个问题。

Answer 1

我看不出有问题，可能是 pdf 文件刚刚损坏。 在另一个 PDF 文件中测试或只更新您的 Android Studio。 在我的例子中，在我实施快速 Android 网络之前，文件有时会损坏，但在我实施快速 Android 网络之后，文件没有损坏。

在 Gradle 中粘贴这个

implementation 'com.amitshekhar.android:android-networking:1.0.2'

并在 Manifest.xml 上添加 Inte.net 权限

<uses-permission android:name="android.permission.INTERNET" />

然后在 onCreate() 方法中初始化应用 class

AndroidNetworking.initialize(getApplicationContext());

我认为我的解释不是很好，你可以在https://github.com/amitshekhariitbhu/Fast-Android-Networking查看

如果这不能让你解决问题，我很抱歉，但根据我的情况，它解决了

Answer 2

我下载的文件不断损坏，我将其处理为：

JavaScriptInterface.kt

package com.hamza.hiwhatsappweb.utils

import android.R
import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Environment
import android.os.Handler
import android.util.Base64
import android.util.Log
import android.webkit.JavascriptInterface
import android.widget.Toast
import androidx.core.app.NotificationCompat
import androidx.core.content.FileProvider
import java.io.File
import java.io.FileOutputStream
import java.io.IOException


class JavaScriptInterface(private val context: Context) {
    @JavascriptInterface
    @Throws(IOException::class)
    fun getBase64FromBlobData(base64Data: String) {
        Log.e("mimeType", "getBase64FromBlobData:  $mimTp")
        convertBase64StringToPdfAndStoreIt(base64Data)
    }

    @Throws(IOException::class)
    private fun convertBase64StringToPdfAndStoreIt(base64PDf: String) {
        Log.e("BASE 64", base64PDf)
        val notificationId = 1
        val dwldsPath = File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString() + "/$fileName")
        val pdfAsBytes =
            Base64.decode(base64PDf.replaceFirst("^data:$mimTp;base64,".toRegex(), ""), 0)
        val os = FileOutputStream(dwldsPath, false)
        os.write(pdfAsBytes)
        os.flush()
        if (dwldsPath.exists()) {
            val intent = Intent()
            intent.action = Intent.ACTION_VIEW
            val apkURI = FileProvider.getUriForFile(context, context.applicationContext.packageName + ".provider", dwldsPath)
            intent.setDataAndType(apkURI, mimTp)
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
            val pendingIntent =
                PendingIntent.getActivity(context, 1, intent, PendingIntent.FLAG_CANCEL_CURRENT)
            val CHANNEL_ID = "MYCHANNEL"
            val notificationManager =
                context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                val notificationChannel =
                    NotificationChannel(CHANNEL_ID, "name", NotificationManager.IMPORTANCE_HIGH)
                val notification = Notification.Builder(
                    context, CHANNEL_ID
                )
                    .setContentText(fileName)
                    .setContentTitle("File downloaded")
                    .setContentIntent(pendingIntent)
                    .setChannelId(CHANNEL_ID)
                    .setSmallIcon(R.drawable.sym_action_chat)
                    .build()
                if (notificationManager != null) {
                    notificationManager.createNotificationChannel(notificationChannel)
                    notificationManager.notify(notificationId, notification)
                }
            } else {
                val b = NotificationCompat.Builder(context, CHANNEL_ID)
                    .setDefaults(NotificationCompat.DEFAULT_ALL)
                    .setWhen(System.currentTimeMillis())
                    .setSmallIcon(R.drawable.sym_action_chat) //.setContentIntent(pendingIntent)
                    .setContentTitle("MY TITLE")
                    .setContentText("MY TEXT CONTENT")
                if (notificationManager != null) {
                    notificationManager.notify(notificationId, b.build())
                    val h = Handler()
                    val delayInMilliseconds: Long = 1000
                    h.postDelayed({ notificationManager.cancel(notificationId) }, delayInMilliseconds)
                }
            }
        }
        Toast.makeText(context, "PDF FILE DOWNLOADED!", Toast.LENGTH_SHORT).show()
    }

    companion object {
        var mimTp:String = ""
        var fileName:String = ""
        fun getBase64StringFromBlobUrl(blobUrl: String, mimeType: String,fileName:String): String {
            mimTp = mimeType
            this.fileName = fileName
            return if (blobUrl.startsWith("blob")) {
                "javascript: var xhr = new XMLHttpRequest();" +
                        "xhr.open('GET', '" + blobUrl + "', true);" +
                        "xhr.setRequestHeader('Content-type','$mimeType');" +
                        "xhr.responseType = 'blob';" +
                        "xhr.onload = function(e) {" +
                        "    if (this.status == 200) {" +
                        "        var blobPdf = this.response;" +
                        "        var reader = new FileReader();" +
                        "        reader.readAsDataURL(blobPdf);" +
                        "        reader.onloadend = function() {" +
                        "            base64data = reader.result;" +
                        "            Android.getBase64FromBlobData(base64data);" +
                        "        }" +
                        "    }" +
                        "};" +
                        "xhr.send();"
            } else "javascript: console.log('It is not a Blob URL');"
        }
    }
}

在 Webview 上设置此属性：

binding?.webView?.addJavascriptInterface(JavaScriptInterface(applicationContext), "Android")
        binding?.webView?.settings?.pluginState = WebSettings.PluginState.ON

        binding?.webView?.setDownloadListener { url, _, contentDisposition, mimetype, _ ->
//           downloadFiles(url, mimetype, contentDisposition)
            val pdfUrl: String? = url?.trim()?.replace("blob:", "")
            val fileName = URLUtil.guessFileName(pdfUrl, contentDisposition, mimetype)

            binding?.webView?.loadUrl(JavaScriptInterface.getBase64StringFromBlobUrl(url,mimetype,fileName))

        }

provider_paths.xml

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path name="external_files" path="."/>
</paths>

将此代码粘贴到 AndroidManifest.xml 文件中的应用程序下

<provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="${applicationId}.provider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_paths" />
        </provider>