Webページのソースコードを取得

MainFragment.kt

package com.example.webscrapingtest.view

import androidx.lifecycle.ViewModelProvider
import android.os.Bundle
import android.util.Log
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.webkit.JavascriptInterface
import android.webkit.WebView
import android.webkit.WebViewClient
import androidx.databinding.DataBindingUtil
import com.example.webscrapingtest.R
import com.example.webscrapingtest.databinding.MainFragmentBinding
import com.example.webscrapingtest.viewmodel.MainViewModel
import kotlinx.android.synthetic.main.main_fragment.view.*

class MainFragment : Fragment() {

    private lateinit var webViewModel: MainViewModel
    private lateinit var binding: MainFragmentBinding

    companion object {
        fun newInstance() = MainFragment()
    }

    private lateinit var viewModel: MainViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        binding = DataBindingUtil.inflate(inflater, R.layout.main_fragment, container, false)
        binding.setLifecycleOwner(this)

        val view = binding.root
        view.webView.settings.javaScriptEnabled = true
        // 規定のブラウザではなく、WebViewで表示するためコード
        view.webView.webViewClient = object : ViewSourceClient(){}
        view.webView.addJavascriptInterface(this, "fragment")
        view.webView.loadUrl("https://yahoo.co.jp/")

        return binding.getRoot()
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProvider(this).get(MainViewModel::class.java)
        // TODO: Use the ViewModel
    }

    open class ViewSourceClient : WebViewClient() {
        override fun onPageFinished(view: WebView, url: String) {
            view.loadUrl("javascript:window.fragment.viewSource(document.getElementsByTagName('html')[0].outerHTML);")
        }
    }

    @JavascriptInterface
    fun viewSource(src: String) {
        Log.d("Test", src)
    }
}