当我从一个选项卡切换到另一个选项卡时，我的片段中的 Webview 总是刷新

Question

我想保存片段的瞬间，然后在重新打开选项卡时恢复。从一个选项卡切换到另一个选项卡时。这是我的片段代码：

package com.mhm.universityofwah.fragments;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.fragment.app.Fragment;

import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.mhm.universityofwah.R;

import org.jetbrains.annotations.NotNull;

import java.util.Objects;

import jp.co.recruit_lifestyle.android.widget.WaveSwipeRefreshLayout;

public class WebFragment extends Fragment implements WaveSwipeRefreshLayout.OnRefreshListener {

    private WaveSwipeRefreshLayout swipeRefreshLayout;
    private WebView mWebView;
    private Activity context;
    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setRetainInstance(true);
        View view = inflater.inflate(R.layout.fragment_avicenna, container, false);
        mWebView = (WebView) view.findViewById(R.id.webview);
        swipeRefreshLayout = (WaveSwipeRefreshLayout) view.findViewById(R.id.swipeContainer);
        swipeRefreshLayout.setOnRefreshListener((WaveSwipeRefreshLayout.OnRefreshListener) WebFragment.this);
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);
                swipeRefreshLayout.setRefreshing(true);
            }

            public void onPageFinished(WebView view, String url) {
                swipeRefreshLayout.setRefreshing(false);
            }
        });
        BottomNavigationView bottomNavigationView=view.findViewById(R.id.bottom_navigation);
        bottomNavigationView.setOnNavigationItemSelectedListener(navListner);
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setAllowFileAccess(true);
        webSettings.setAppCacheEnabled(true);
        mWebView.getSettings().setSupportZoom(true);
        mWebView.getSettings().setBuiltInZoomControls(true);
        mWebView.getSettings().setDisplayZoomControls(false);
        mWebView.setWebViewClient(new Callback());
        if(savedInstanceState==null){
            loadWebsite();
        }
        return view;
    }
    private BottomNavigationView.OnNavigationItemSelectedListener navListner=
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                    switch (item.getItemId()){
                        case R.id.nav_refresh:
                            mWebView.reload();
                            break;
                        case R.id.nav_back:
                            if(mWebView.canGoBack()){
                                mWebView.goBack();
                            }
                            break;
                        case R.id.nav_forward:
                            if(mWebView.canGoForward()){
                                mWebView.goForward();
                            }
                            break;
                    }
                    return true;
                }
            };
    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    private void loadWebsite() {
        ConnectivityManager cm  = (ConnectivityManager) Objects.requireNonNull(getActivity()).getSystemService(Context.CONNECTIVITY_SERVICE);
        assert cm != null;
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnectedOrConnecting()) {
            mWebView.loadUrl("http://uow.edu.pk");
        } else {
            Toast.makeText(Objects.requireNonNull(getActivity()).getApplicationContext(), "Please Check Network Connection!", Toast.LENGTH_SHORT).show();
            swipeRefreshLayout.setRefreshing(false);
        }
    }

    public class Callback extends WebViewClient {
        @RequiresApi(api = Build.VERSION_CODES.KITKAT)
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
            Toast.makeText(Objects.requireNonNull(getActivity()).getApplicationContext(), "Please Check Network Connection!", Toast.LENGTH_SHORT).show();
        }
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (url.endsWith(".pdf")) {
                startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
                return true;
            }else if (url.contains("mailto:")) {
                view.getContext().startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
                return true;
            }else if (url.startsWith("tel:")) {
                Intent intent = new Intent(Intent.ACTION_DIAL, Uri.parse(url));
                startActivity(intent);
                return true;
            }else {
                view.loadUrl(url);
                return true;
            }
        }

        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            swipeRefreshLayout.setRefreshing(true);
        }


        public void onPageFinished(WebView view, String url) {
            swipeRefreshLayout.setRefreshing(false);
        }
    }

    @Override
    public void onRefresh() {
        mWebView.reload();
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (savedInstanceState != null) {
            mWebView.restoreState(savedInstanceState);
        }
    }
    @Override
    public void onSaveInstanceState(@NotNull Bundle outState )
    {
        super.onSaveInstanceState(outState);
        mWebView.saveState(outState);
    }

    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    public boolean onKey(View v, int keyCode, KeyEvent event ) {
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            switch (keyCode) {
                case KeyEvent.KEYCODE_BACK:
                    if (mWebView.canGoBack()) {
                        mWebView.goBack();
                    } else {
                        Objects.requireNonNull(getActivity()).finish();
                    }
                    return true;
            }
        }
        // here your code
        return false;
    }

    @Override
    public void onAttach(@NonNull Context context) {
        super.onAttach(context);
        this.context = (Activity) context;
    }
}

我有 4 个选项卡，但是当我从一个选项卡切换到另一个选项卡并返回到第一个选项卡时，它总是会重新加载。我尝试了一切，但我的问题没有解决。请帮助我完成这件事。

Answer 1

@RequiresApi(api = Build.VERSION_CODES.KITKAT)
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
   // setRetainInstance(true);

 if(view == null){
    view = inflater.inflate(R.layout.fragment_avicenna, container, false);
    mWebView = (WebView) view.findViewById(R.id.webview);
    swipeRefreshLayout = (WaveSwipeRefreshLayout) view.findViewById(R.id.swipeContainer);
    swipeRefreshLayout.setOnRefreshListener((WaveSwipeRefreshLayout.OnRefreshListener) WebFragment.this);
    mWebView.setWebViewClient(new WebViewClient() {
        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            swipeRefreshLayout.setRefreshing(true);
        }

        public void onPageFinished(WebView view, String url) {
            swipeRefreshLayout.setRefreshing(false);
        }
    });
    BottomNavigationView bottomNavigationView=view.findViewById(R.id.bottom_navigation);
    bottomNavigationView.setOnNavigationItemSelectedListener(navListner);
    WebSettings webSettings = mWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webSettings.setAllowFileAccess(true);
    webSettings.setAppCacheEnabled(true);
    mWebView.getSettings().setSupportZoom(true);
    mWebView.getSettings().setBuiltInZoomControls(true);
    mWebView.getSettings().setDisplayZoomControls(false);
    mWebView.setWebViewClient(new Callback());
    if(savedInstanceState==null){
        loadWebsite();
    }
  }
    return view;
}

请将视图设为全局变量，并在 onCreate 视图重新创建视图时添加 null 检查，因此请添加检查，如果视图 != null 则仅 return 已经初始化视图而不是再次创建视图

当我从一个选项卡切换到另一个选项卡时，我的片段中的 Webview 总是刷新

My Webview in fragment always refresh when i switch my tab from one to other

android

fragment

webview