如何使用Android Kotlin在WebView中加载URL？

Question

我是Android和Kotlin的新手.

任何人都可以帮我加载一个URL webView？

我只是想在应用程序打开时加载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" />

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.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

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，请尝试此完整示例并按照说明进行操作，这样您只需编辑网站的 URL 和干净的域名即可。

Answer 3

这是在 android 中加载网站的完整工作代码webView。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 视图中加载它的 URL。

• 它将在 webview 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
• 如果加载网站时出现问题，处理错误
• 处理后退按钮新闻案例
• 使用 toast 处理退出应用程序确认

活动_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>

主活动.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()
    }
}

进度.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>

清单.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>

字符串.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>

构建.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'

}

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