WebView加载时解决Loading闪烁问题

一般移动端加载H5时需要点时间，所以这个时候经常加个Load in g。

常规的做法：

1.在webview刚开始的时候show loading,等WebViewClient回调onPa geFini shed的时候hide loading,

2.Webview先setWebViewClient(mWebClient),在WebViewClient的 onPa geStar ted()回调中show loading 在onPa geFini s hed()中hide loading

以上的做法正常情况下都没有问题，但是一旦遇到加载的网页中出现重定向的时候onPa geSt ar ted()和onPa geFini s hed() 会走多次，这个时候就会出现loading 闪烁问题

解决办法：其实在onPa geFini s hed()的回调中可以通过webview拿到当前的progres s,根据progres s的进度来决定是否隐藏 loading

public class MainActivity extends AppCompatActivity {

    private WebView mWebView;
    private ProgressBar mProgressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mWebView = findViewById(R.id.wv_web_view);
        mProgressBar = findViewById(R.id.pb_view);
        showProgressBar();
        initWebView();
        mWebView.loadUrl("https://www.baidu.com/");
    }  

    private void initWebView() {
        mWebView.setWebChromeClient(new WebChromeClient());
        mWebView.setWebViewClient(mWebClient);
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.setInitialScale(25);
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setCacheMode(WebSettings.LOAD_NO_CACHE);
        webSettings.setJavaScriptEnabled(true);
        webSettings.setDomStorageEnabled(true);
        webSettings.setDatabaseEnabled(true);
        webSettings.setAllowFileAccess(true);
        webSettings.setAppCacheEnabled(true);
        webSettings.setSupportZoom(true);
        webSettings.setDefaultTextEncodingName("UTF-8");
        webSettings.setJavaScriptCanOpenWindowsAutomatically(true);
        webSettings.setUseWideViewPort(true);
        webSettings.setBuiltInZoomControls(false);
        webSettings.setLayoutAlgorithm(WebSettings.LayoutAlgorithm.SINGLE_COLUMN);
        webSettings.setLoadWithOverviewMode(true);
    }

    private WebViewClient mWebClient = new WebViewClient() {

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
            Log.i("aaa", "onPageFinished  progress : " + view.getProgress());
            if (view.getProgress() == 100) {
                hideProgressBar();
            }
        }


        @Override
        public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
            return super.shouldOverrideUrlLoading(view, request);
        }

        @Override
        public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
            super.onReceivedError(view, request, error);
            Log.i("aaa", "onReceivedError  error : " + error);
            hideProgressBar();
        }

        @Override
        public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
            super.onReceivedSslError(view, handler, error);
            Log.i("aaa", "onReceivedSslError  error : " + error);
            hideProgressBar();
        }
    };

    public void showProgressBar() {
        if (mProgressBar != null) {
            mProgressBar.setVisibility(View.VISIBLE);
        }
    }

    public void hideProgressBar() {
        if (mProgressBar != null) {
            mProgressBar.setVisibility(View.GONE);
        }
    }

    @Override
    public void onBackPressed() {
        if (mWebView.canGoBack()) {
            mWebView.goBack();
        } else {
            finish();
        }
    }


}