加载webview应用程序时在顶部显示进度条

Question

我正在尝试在应用程序的顶部显示进度条,如谷歌浏览器为Android显示加载网站时加载栏.

当用户点击webview应用程序的任何内部链接时,我想显示此进度条...就像谷歌浏览器显示一样.

这是我尝试过的,这段代码不起作用,app即使不启动也会停止工作.

public class MainActivity extends AppCompatActivity {

    private WebView mWebView;
    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setBackgroundDrawable(null);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        progressBar.setMax(100);
        setContentView(R.layout.activity_main);

        mWebView = (WebView) findViewById(R.id.main_webview);
        mWebView.setWebViewClient(new WebViewClient() {

            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);
                progressBar.setVisibility(View.VISIBLE);
                progressBar.setProgress(0);
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);
                progressBar.setVisibility(View.GONE);
                progressBar.setProgress(100);
                if (mWebView.getProgress() == 100) {

                    // show webview
                    mWebView.setVisibility(View.VISIBLE);
                    // hide splash
                    findViewById(R.id.splash_screen).setVisibility(View.GONE);
                }
            }

            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {

                if (Uri.parse(url).getHost().contains("www.example.com")) {
                    return false;
                }

                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                view.getContext().startActivity(intent);
                return true;

            }

            public void onReceivedError(WebView view, int errorCode,
                                        String description, String failingUrl) {
                view.loadUrl("file:///android_asset/offline.html");
            }

        });

        mWebView.loadUrl("http://www.example.com/?m=1");
    }

}

主要活动:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/splash_screen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:src="@mipmap/splash_logo"
        android:visibility="visible" />

    <WebView
        android:id="@+id/main_webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone" />
    <ProgressBar
        android:id="@+id/progressBar"
        android:minHeight="2dip"
        android:maxHeight="2dip"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        style="@android:style/Widget.ProgressBar.Horizontal" />
</RelativeLayout>

Answer 1

您创建MyWebChromeClient

public class MyWebChromeClient extends WebChromeClient {
private ProgressListener mListener;

public MyWebChromeClient(ProgressListener listener) {
    mListener = listener;
}

@Override
public void onProgressChanged(WebView view, int newProgress) {
    mListener.onUpdateProgress(newProgress);
    super.onProgressChanged(view, newProgress);
}

public interface ProgressListener {
    public void onUpdateProgress(int progressValue);
}
}

在您的MainActivity中

public class MainActivity extends AppCompatActivity implements MyWebChromeClient.ProgressListener{
private WebView mWebView;
private ProgressBar mProgressBar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mWebView = (WebView) findViewById(R.id.webView);
    WebSettings webSettings = mWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);

    // add progress bar
    mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
    mWebView.setWebChromeClient(new MyWebChromeClient(this));
    mWebView.setWebViewClient(new WebViewClient() {

        public boolean shouldOverrideUrlLoading(WebView view, String url) {

            view.loadUrl(url);


            return true;
        }

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

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
            mProgressBar.setVisibility(View.GONE);

        }


    });


}


@Override
public void onUpdateProgress(int progressValue) {
    mProgressBar.setProgress(progressValue);
    if (progressValue == 100) {
        mProgressBar.setVisibility(View.INVISIBLE);
    }
}
}

在activity_main.xml中

<RelativeLayout
    android:id="@+id/relative_web_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="@dimen/progress_bar_height"
        android:progressDrawable="@drawable/bg_progress_bar_webview" />

    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/progressBar" />
</RelativeLayout>

在drawable中创建bg_progress_bar_webview.xml

 <?xml version="1.0" encoding="utf-8"?>
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

<item
    android:id="@android:id/background"
    android:drawable="@android:color/transparent"/>
<item android:id="@android:id/secondaryProgress">
    <scale
        android:drawable="@color/progress_bar_second"
        android:scaleWidth="100%" />
</item>
<item android:id="@android:id/progress">
    <scale
        android:drawable="@color/progress_bar_runing"
        android:scaleWidth="100%" />
</item>

</layer-list>

希望!它可以帮助你