Android WebView

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="tjs.android.tkygw">
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:networkSecurityConfig="@xml/network_security_config"
        android:usesCleartextTraffic="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>

public class MainActivity extends AppCompatActivity {

    private WebView webView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView=findViewById(R.id.webView);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setAllowContentAccess(true);
        webView.getSettings().setDomStorageEnabled(true);
        webView.getSettings().setDatabaseEnabled(true);
        // webview的设置中添加如下代码
        try {
            if (Build.VERSION.SDK_INT >= 16) {
                Class<?> clazz = webView.getSettings().getClass();
                Method method = clazz.getMethod("setAllowUniversalAccessFromFileURLs", boolean.class);
                if (method != null) {
                    method.invoke(webView.getSettings(), true);
                }
            }
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        webView.loadUrl("");
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(KeyEvent.KEYCODE_BACK==keyCode && webView.canGoBack()){
            webView.goBack();
            return  true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
<WebView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/webView">
</WebView>


</androidx.constraintlayout.widget.ConstraintLayout>