没有带有拉动刷新的互联网消息 webview 片段

Posted 2023-05-07

【中文标题】没有带有拉动刷新的互联网消息 webview 片段

【英文标题】：No internet message webview fragment with pull do to refresh

【发布时间】：2017-12-28 00:34:12

【问题描述】：

我在这里搜索“没有互联网消息”的网页视图，我尝试了一些代码，但没有成功。我在片段中有一个 WebView，我想检查设备是否有互联网。如果是，webview 将加载。如果没有，将加载另一个片段，并且这个新片段将膨胀一个没有互联网消息的布局，并且这个布局将有一个刷新按钮（或下拉刷新）。那么，如何实现网络检查和刷新呢？

主要活动

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener 

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    if(null == savedInstanceState) 
        // set you initial fragment object
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.content, InicioPagina.newInstance());
        transaction.commit();
    

WebView 片段

public class InicioPagina extends Fragment 

private ProgressBar prg;
SwipeRefreshLayout mySwipeRefreshLayout;
public WebView myWebView;

public static InicioPagina newInstance() 
    InicioPagina fragment = new InicioPagina();
    return fragment;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    View rootView = inflater.inflate(R.layout.iniciopagina, container, false);
    prg = (ProgressBar)rootView.findViewById(R.id.progressBar2);
    mySwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.swipelayout);
    myWebView = (WebView) rootView.findViewById(R.id.inicio_pagina);
    myWebView.loadUrl("http://example.com.br/");

    //*Ativar javascript
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);

    //*Forçar links para abrir no WebView ao invés do navegador
    myWebView.setWebViewClient(new WebViewClient());


    myWebView.setVerticalScrollBarEnabled(false);

    mySwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() 
        @Override
        public void onRefresh() 
            myWebView.reload();
            mySwipeRefreshLayout.setRefreshing(false);
        
    );

    myWebView.setOnKeyListener(new View.OnKeyListener()
    
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event)
        
            if(event.getAction() == KeyEvent.ACTION_DOWN)
            
                WebView webView = (WebView) v;

                switch(keyCode)
                
                    case KeyEvent.KEYCODE_BACK:
                        if(webView.canGoBack())
                        
                            webView.goBack();
                            return true;
                        
                        break;
                
            

            return false;
        
    );

    return rootView;


public class WebViewClient extends android.webkit.WebViewClient
    @Override
    public void onPageStarted(WebView view, String url, Bitmap favicon) 
        prg.setVisibility(View.VISIBLE);
        super.onPageStarted(view, url, favicon);
    
    @Override
    public void onPageFinished(WebView view, String url) 
        prg.setVisibility(View.GONE);

        super.onPageFinished(view, url);
    

内容主xml

<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_
android:layout_
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/app_bar_main"
tools:context="br.com.example.example.MainActivity">
<RelativeLayout
    android:layout_
    android:layout_>
        <FrameLayout
            android:id="@+id/content"
            android:layout_
            android:layout_></FrameLayout>
</RelativeLayout>

非网络布局

<TextView
    android:layout_
    android:layout_
    android:text="Sem acesso a internet"
    android:textAlignment="center"
    android:textSize="30sp" />

【参考方案1】：

您可以通过访问网络状态来检查互联网可用性：

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

您可以通过这种方法检查互联网：

 private boolean haveNetworkConnection() 
    boolean haveConnectedWifi = false;
    boolean haveConnectedMobile = false;

    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo[] netInfo = cm.getAllNetworkInfo();
    for (NetworkInfo ni : netInfo) 
        if (ni.getTypeName().equalsIgnoreCase("WIFI"))
            if (ni.isConnected())
                haveConnectedWifi = true;
        if (ni.getTypeName().equalsIgnoreCase("MOBILE"))
            if (ni.isConnected())
                haveConnectedMobile = true;
    
    return haveConnectedWifi || haveConnectedMobile;

前：

if (!haveNetworkConnection()) 
        //inflate your fragment, THERE IS NO INTERNET!!
    else 
       //you can reload or what ever you want now.
   

【讨论】：

我有一个错误：无法解析方法“getSystemService(java.lang.String)”

@TonyStarkus 如果您在片段中使用，请使用 `getActivity()

我在 WebView 片段中使用了这个方法。我将“getSystemService”更改为“getActivity()”，现在错误出现在下一部分：“(Context.CONNECTIVITY_SERVICE);”出现错误

当我关闭互联网并打开应用程序时，我会强制关闭。在“如果”中，我只需输入“inflater.inflate(R.layout.nointernet, container, false);”

【参考方案2】：

在我的例子中，我使用 AlertDialogBox 来显示 Internet 错误并在重试按钮上检查 Internet 连接

 @Override
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) 
            //Clearing the WebView
            try 
                webView.stopLoading();
             catch (Exception e) 
            
            try 
                webView.clearView();
             catch (Exception e) 
            
            if (webView.canGoBack()) 
                webView.goBack();
            
            webView.loadUrl("about:blank");
            AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create();
            alertDialog.setTitle("Error");
            alertDialog.setMessage("Check your internet connection and try again.");
            alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Try Again", new DialogInterface.OnClickListener() 
                public void onClick(DialogInterface dialog, int which) 
                    finish();
                    startActivity(getIntent());
                
            );
            alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "Cancel", new DialogInterface.OnClickListener() 
                @Override
                public void onClick(DialogInterface dialogInterface, int i) 
                    finish();
                
            );
            alertDialog.setCancelable(false);
            alertDialog.show();
            super.onReceivedError(webView, errorCode, description, failingUrl);