离线时WebView不起作用：ERR_INTERNET_DISCONNECTED

问题描述

我正在尝试使用WebView创建一个android应用程序。我希望它在内联时存储在缓存中，而在脱机时读入缓存。 内联时，没问题：它可以工作。 但是，当我将手机置于飞行模式并刷新应用程序时，出现“网页不可用”的提示。 有人有主意吗？

MainActivity.java：

package com.example.essai2;

import androidx.appcompat.app.AppCompatActivity;

import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {

    public WebView webView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        WebView webView = new WebView(this);
        setContentView(webView);
        webView.setWebViewClient(new WebViewClient());
        WebSettings settings = webView.getSettings();
        settings.setSupportMultipleWindows(false);
        settings.setLightTouchEnabled(true);
        settings.setLoadsImagesAutomatically(true);
        settings.setSaveFormData(true);
        settings.setJavaScriptEnabled(true);
        settings.setAllowFileAccess(true); // dowload/streams de fichiers tels mp4,0gg etc..
        settings.setAllowFileAccessFromFileURLs(true);
        settings.setAllowUniversalAccessFromFileURLs(true);
        // La webview sera charge complétement et normalement (sans zoom)
        settings.setLoadWithOverviewmode(true);
        settings.setUseWideViewPort(true);
        settings.setSupportZoom(true);
        // Afficher le contrôle de zoom
        settings.setBuiltInZoomControls(true);
        settings.setUseWideViewPort(true);
        settings.setDomStorageEnabled(true);
        settings.setDatabaseEnabled(true);
        settings.setAppCacheEnabled(true);
        settings.setCacheMode(WebSettings.LOAD_DEFAULT );

        settings.setAppCacheMaxSize(1024*1024*8);
        settings.setAppCachePath(getApplicationContext().getCacheDir().getAbsolutePath() );
        if ( !isNetworkAvailable() ) { // loading offline
            webView.getSettings().setCacheMode( WebSettings.LOAD_CACHE_ELSE_NETWORK );
        }

        webView.loadUrl("https://effisoft.ovh/test/test.htm");
    }

    private boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService( CONNECTIVITY_SERVICE );
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null && activeNetworkInfo.isConnected();
    }

}

AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.essai2">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_WIFI_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:theme="@style/AppTheme"
        android:usesCleartextTraffic="true"
        android:launchMode="singleTask"
        >
        <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>

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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"/>

解决方法

尝试增加您的AppCacheMaxSize，问题可能是缓存中的空间不足，并且WebView被迫从网络上重新加载。