javascript - 安卓 WebView : Can't go back to previous page

Question

(我是新手)我从一个人那里买了一个 android 应用程序源，我用我的链接替换了他的链接，所以现在 webview 指向我的网站。一切正常，但后退按钮有问题。如果我按下它，应用程序将关闭(更像是最小化，应用程序会继续在后台运行)而不是返回到上一页。我已经尝试了在谷歌上找到的多种解决方案，但它们都在做同样的事情。我买的那个人没有回复我的消息，所以我在这里问，也许你们会帮助我。

我会提供任何其他需要的信息。我不想成为应用程序开发人员，所以如果你们能用更简单的术语解释解决方案，我将不胜感激。

主要 Activity .java(我希望这是需要修改的代码)

/*
       Licensed to the Apache Software Foundation (ASF) under one
       or more contributor license agreements.  See the NOTICE file
       distributed with this work for additional information
       regarding copyright ownership.  The ASF licenses this file
       to you under the Apache License, Version 2.0 (the
       "License"); you may not use this file except in compliance
       with the License.  You may obtain a copy of the License at

         http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing,
       software distributed under the License is distributed on an
       "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
       KIND, either express or implied.  See the License for the
       specific language governing permissions and limitations
       under the License.
 */

package com.myapp.music;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Toast;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.InterstitialAd;
import com.onesignal.OneSignal;

import org.apache.cordova.*;

public class MainActivity extends CordovaActivity
{
    boolean doubleBackToExitPressedOnce = false;
    private InterstitialAd mInterstitialAd;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        Bundle extras = getIntent().getExtras();
        if (extras != null && extras.getBoolean("cdvStartInBackground", false)) {
            moveTaskToBack(true);
        }


        ConnectivityManager cm = (ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        if (activeNetwork != null && activeNetwork.isConnected()) {
            loadUrl(launchUrl);
        }

        else {

            Toast.makeText(this,"Device is not connected to the internet",Toast.LENGTH_LONG).show();

            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setTitle("Error :(");
            builder.setMessage("No internet connection").setCancelable(false)

                    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            finish();
                        }
                    });
            AlertDialog alert = builder.create();
            alert.show();


        }


        //OneSignal Push Notification
        OneSignal.startInit(this)
                .inFocusDisplaying(OneSignal.OSInFocusDisplayOption.Notification)
                .unsubscribeWhenNotificationsAreDisabled(true)
                .init();

        //Interstitial - To enable the Admob Ads, Uncomment the below code

             /* prepareAd();

        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                if (mInterstitialAd.isLoaded()) {
                    mInterstitialAd.show();
                } else {
                    Log.d("TAG", " Interstitial AD not loaded");
                }

            }
        }, 30000); //Ads will be shown after 30 seconds */

        UiChangeListener();

    }

    public void UiChangeListener()
    {
        final View decorView = getWindow().getDecorView();
        decorView.setOnSystemUiVisibilityChangeListener (new View.OnSystemUiVisibilityChangeListener() {
            @Override
            public void onSystemUiVisibilityChange(int visibility) {
                if ((visibility & View.SYSTEM_UI_FLAG_FULLSCREEN) == 0) {
                    decorView.setSystemUiVisibility(
                            View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                                    | View.SYSTEM_UI_FLAG_FULLSCREEN
                                    | View.SYSTEM_UI_FLAG_IMMERSIVE);
                }
            }
        });

    }

    public void onBackPressed() {
        if (doubleBackToExitPressedOnce) {
            super.onBackPressed();
            return;
        }

        this.doubleBackToExitPressedOnce = true;
        Toast.makeText(this, "Press again to exit", Toast.LENGTH_SHORT).show();

        new Handler().postDelayed(new Runnable() {

            @Override
            public void run() {
                doubleBackToExitPressedOnce=false;
            }
        }, 2000);
    }

    public void  prepareAd(){

        mInterstitialAd = new InterstitialAd(this);
        mInterstitialAd.setAdUnitId(""); //replace with your Admob ID
        mInterstitialAd.loadAd(new AdRequest.Builder().build());
    }
}

Answer 1

在 onBackButtonPressed 中使用这个

public void onBackPressed() {
        if (doubleBackToExitPressedOnce) {
            super.onBackPressed();
            return;
        }

      if(webView.canGoBack()){
         webView.goBack();
       }

        this.doubleBackToExitPressedOnce = true;
        Toast.makeText(this, "Press again to exit", Toast.LENGTH_SHORT).show();

        new Handler().postDelayed(new Runnable() {

            @Override
            public void run() {
                doubleBackToExitPressedOnce=false;
            }
        }, 2000);
    }