如何使用 Android Kotlin 在 WebView 中加载 URL？

Question

我是 Android 和 Kotlin 的新手。

谁能帮我在webView 中加载一个网址？

我只想在应用打开时加载 URL 并查看网页。

Answer 1

1.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.kotlinwebview.MainActivity">


<WebView
    android:id="@+id/webview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:ignore="MissingConstraints"
    tools:layout_editor_absoluteX="8dp"
    tools:layout_editor_absoluteY="8dp" />
    
</android.support.constraint.ConstraintLayout>

2.MainActivity.kt

class MainActivity : AppCompatActivity() {

    private lateinit var webView: WebView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        webView = findViewById(R.id.webview)
        webView.settings.setJavaScriptEnabled(true)

        webView.webViewClient = object : WebViewClient() {
            override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
                view?.loadUrl(url)
                return true
            }
        }
        webView.loadUrl("https://www.google.co.in/")
    }
}

Answer 2

这是在 android webView 中加载网站的完整工作代码。只需从 android studio 创建一个新项目并使用以下代码加载 web 视图。只需更改要在 Web 视图中加载的 URL。

• 它将在 web 视图中加载一个网站
• 它将检查互联网连接的可用性
• 如果没有互联网，请用户从小吃店消息中启用 WiFi
• 加载进度，直到网站加载
• 在加载网站时出现问题时处理错误
• 处理后退按钮按下案例
• 使用 toast 处理退出应用程序确认

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/rootView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/infoTV"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.kt：

import android.annotation.SuppressLint
import android.content.Context
import android.content.Intent
import android.graphics.Bitmap
import android.net.ConnectivityManager
import android.net.NetworkCapabilities
import android.os.Bundle
import android.os.Handler
import android.os.Looper
import android.provider.Settings
import android.util.Log
import android.view.KeyEvent
import android.webkit.WebResourceError
import android.webkit.WebResourceRequest
import android.webkit.WebView
import android.webkit.WebViewClient
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.snackbar.Snackbar
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    private var progress: Progress? = null
    private var isLoaded: Boolean = false
    private var doubleBackToExitPressedOnce = false
    private var webURL = "https://www.geeklabs.co.in/" // Change it with your URL

    @SuppressLint("SetJavaScriptEnabled")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        webView.settings.javaScriptEnabled = true
        if (!isOnline()) {
            showToast(getString(R.string.no_internet))
            infoTV.text = getString(R.string.no_internet)
            showNoNetSnackBar()
            return
        }
    }

    override fun onResume() {
        if (isOnline() && !isLoaded) loadWebView()
        super.onResume()
    }

    private fun loadWebView() {
        infoTV.text = ""
        webView.loadUrl(webURL)
        webView.webViewClient = object : WebViewClient() {
            override fun shouldOverrideUrlLoading(view: WebView?, request: WebResourceRequest?): Boolean {
                val url = request?.url.toString()
                view?.loadUrl(url)
                return super.shouldOverrideUrlLoading(view, request)
            }

            override fun onPageStarted(view: WebView?, url: String?, favicon: Bitmap?) {
                setProgressDialogVisibility(true)
                super.onPageStarted(view, url, favicon)
            }

            override fun onPageFinished(view: WebView?, url: String?) {
                isLoaded = true
                setProgressDialogVisibility(false)
                super.onPageFinished(view, url)
            }

            override fun onReceivedError(view: WebView, request: WebResourceRequest, error: WebResourceError) {
                isLoaded = false
                val errorMessage = "Got Error! $error"
                showToast(errorMessage)
                infoTV.text = errorMessage
                setProgressDialogVisibility(false)
                super.onReceivedError(view, request, error)
            }
        }
    }

    override fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {
        if (event.action == KeyEvent.ACTION_DOWN) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {
                if (webView.canGoBack()) {
                    webView.goBack()
                } else {
                    showToastToExit()
                }
                return true
            }
        }
        return super.onKeyDown(keyCode, event)
    }

    private fun showToastToExit() {
        when {
            doubleBackToExitPressedOnce -> {
                onBackPressed()
            }
            else -> {
                doubleBackToExitPressedOnce = true
                showToast(getString(R.string.back_again_to_exit))
                Handler(Looper.myLooper()!!).postDelayed({ doubleBackToExitPressedOnce = false }, 2000)
            }
        }
    }

    private fun setProgressDialogVisibility(visible: Boolean) {
        if (visible) progress = Progress(this, R.string.please_wait, cancelable = true)
        progress?.apply { if (visible) show() else dismiss() }
    }

    private fun isOnline(): Boolean {
        val connectivityManager =
                getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val capabilities =
                connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)
        if (capabilities != null) {
            when {
                capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) -> {
                    Log.i("Internet", "NetworkCapabilities.TRANSPORT_CELLULAR")
                    return true
                }
                capabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) -> {
                    Log.i("Internet", "NetworkCapabilities.TRANSPORT_WIFI")
                    return true
                }
                capabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET) -> {
                    Log.i("Internet", "NetworkCapabilities.TRANSPORT_ETHERNET")
                    return true
                }
            }
        }
        return false
    }

    private fun showToast(message: String) {
        Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
    }

    private fun showNoNetSnackBar() {
        val snack = Snackbar.make(rootView, getString(R.string.no_internet), Snackbar.LENGTH_INDEFINITE)
        snack.setAction(getString(R.string.settings)) {
            startActivity(Intent(Settings.ACTION_WIFI_SETTINGS))
        }
        snack.show()
    }
}

Progress.kt：

import android.app.AlertDialog
import android.app.Dialog
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.widget.TextView
import androidx.annotation.StringRes

class Progress constructor(
    context: Context?,
    @StringRes private val titleRes: Int,
    cancelable: Boolean = false
) {

    private var view: View? = null
    private var builder: AlertDialog.Builder
    private var dialog: Dialog

    init {
        view = LayoutInflater.from(context).inflate(R.layout.progress, null)
        view?.findViewById<TextView>(R.id.text)?.setText(titleRes)
        builder = AlertDialog.Builder(context)
        builder.setView(view)
        dialog = builder.create()
        dialog.setCancelable(cancelable)
    }

    fun setProgressMessage(@StringRes titleRes: Int) {
        view?.findViewById<TextView>(R.id.text)?.setText(titleRes)
    }

    fun show() {
        dialog.show()
    }

    fun dismiss() {
        if (dialog.isShowing) {
            dialog.dismiss()
        }
    }

    fun setProgressDialogVisibility(isVisible: Boolean) {

    }
}

pregress.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center_vertical">

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="16dp" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="@style/TextAppearance.AppCompat.SearchResult.Subtitle"
        tools:text="Loading" />

</LinearLayout>

Manifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.geeklabs.webviewkotlin">

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

    <application
        android:allowBackup="true"
        android:fullBackupContent="false"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

strings.xml：

<resources>
    <string name="app_name">WebViewKotlin</string>
    <string name="please_wait">Please wait&#8230;</string>
    <string name="no_internet">No internet connection!</string>
    <string name="settings">Settings</string>
    <string name="back_again_to_exit">Please click BACK again to exit</string>
</resources>

build.gradle：

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.0"

    defaultConfig {
        applicationId "com.geeklabs.webviewkotlin"
        minSdkVersion 23
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.1'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation 'com.google.android.material:material:1.1.0'
    testImplementation 'junit:junit:4.13'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

}

这是 Git 中心的完整工作代码。 Click here to navigate to Git Hub

Answer 3

将此添加到您的活动中：

@SuppressLint("SetJavaScriptEnabled")
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    setContentView(R.layout.activity_webview)

    val mWebView = findViewById<WebView>(R.id.webview)

    val webSettings = mWebView.settings
    webSettings.javaScriptEnabled = true
    mWebView.loadUrl(getString(R.string.website_url))
    mWebView.webViewClient = HelloWebViewClient()
    WebView.setWebContentsDebuggingEnabled(false)

}

并将以下内容添加到 HelloWebViewClient() 类中，以允许后退按钮导航和出站外部链接：

    override fun shouldOverrideUrlLoading(view: WebView, url: String): Boolean {
        if (Uri.parse(url).host == getString(R.string.website_domain)) {
            return false
        }
        val intent = Intent(Intent.ACTION_VIEW, Uri.parse(url))
        startActivity(intent)
        return true
    }

    override fun onPageFinished(view: WebView, url: String) {
        // TODO Auto-generated method stub
        super.onPageFinished(view, url)
    }

}

override fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {
    if (keyCode == KeyEvent.KEYCODE_BACK && webview.canGoBack()) {
        webview.goBack()
        return true
    }
    return super.onKeyDown(keyCode, event)
}

添加定义website_domain (https://stackoverflow.com/) 和website_host (stackoverflow.com) 的字符串。

如果您为了实现您的目标而遇到困难，请尝试this full sample 并按照说明进行操作，因为您只需要编辑您网站的 URL 和干净的域名。

Answer 4

使用 Android Kotlin 扩展插件。如果您使用的是 Android Studio 3.0 及更高版本，请不要担心。已安装在您的项目中。

在布局中使用WebView的id并调用loadUrl()方法。

Android WebView Example - Kotlin & Java

这里的 WebView id : webview

webview.loadUrl("https://www.androidride.com")

别忘了添加

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

如果您的第三方浏览器使用 WebView 中加载的任何 URL 打开，则提供 WebViewClient。

webview.webViewClient = WebViewClient()

如果您想在 WebView 中播放 youtube 视频，则必须在 WebView 中启用 JavaScript。

webview.settings.javaScriptEnabled = true

如果你是 Android 应用开发的初学者，那么本教程将帮助你解开你对 WebView 的几乎所有疑惑。

click here