首先，我是android平台上的新手。我是一名反应开发人员。由于某些原因，我们需要构建android webview应用。问题是，我们需要在预设时间后或如果可能的话，通过触发器-一旦主页的第一个可见屏幕加载/在移动设备上变为可见，就需要删除加载程序/启动画面，然后，删除2个项目Loader / Splash。
这是因为，在具有3 GB RAM的手机上，我无法将Android Webview应用程序的加载时间提高到8秒以上，而对于6 GB及更高版本的手机，加载时间为5秒。
我正在使用ReactJS，并且知道加载第一个可见屏幕上存在的组件大约需要3秒钟的时间。
这是MainActivity.java文件
public class MainActivity extends AppCompatActivity{
private static final int INPUT_FILE_REQUEST_CODE = 1;
private static final int FILECHOOSER_RESULTCODE = 1;
private static final String TAG = MainActivity.class.getSimpleName();
private WebView webView;
SwipeRefreshLayout swipe;
private WebSettings webSettings;
private ValueCallback<Uri> mUploadMessage;
private Uri mCapturedImageURI = null;
private ValueCallback<Uri[]> mFilePathCallback;
private String mCameraPhotoPath;
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
if (requestCode != INPUT_FILE_REQUEST_CODE || mFilePathCallback == null) {
super.onActivityResult(requestCode, resultCode, data);
return;
}
Uri[] results = null;
// Check that the response is a good one
if (resultCode == Activity.RESULT_OK) {
if (data == null) {
// If there is not data, then we may have taken a photo
if (mCameraPhotoPath != null) {
results = new Uri[]{Uri.parse(mCameraPhotoPath)};
}
} else {
String dataString = data.getDataString();
if (dataString != null) {
results = new Uri[]{Uri.parse(dataString)};
}
}
}
mFilePathCallback.onReceiveValue(results);
mFilePathCallback = null;
} else if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
if (requestCode != FILECHOOSER_RESULTCODE || mUploadMessage == null) {
super.onActivityResult(requestCode, resultCode, data);
return;
}
if (requestCode == FILECHOOSER_RESULTCODE) {
if (null == this.mUploadMessage) {
return;
}
Uri result = null;
try {
if (resultCode != RESULT_OK) {
result = null;
} else {
// retrieve from the private variable if the intent is null
result = data == null ? mCapturedImageURI : data.getData();
}
} catch (Exception e) {
Toast.makeText(getApplicationContext(), "activity :" + e,
Toast.LENGTH_LONG).show();
}
mUploadMessage.onReceiveValue(result);
mUploadMessage = null;
}
}
return;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
swipe = (SwipeRefreshLayout) findViewById(R.id.swipe);
swipe.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
LoadWeb();
}
});
LoadWeb();
}
public void LoadWeb(){
webView = (WebView) findViewById(R.id.activity_main_webview);
webSettings = webView.getSettings();
webView.loadUrl("https://www.example.com"); //change with your website
swipe.setRefreshing(true);
//code from youtube for performance
webSettings.setJavaScriptEnabled(true);
webSettings.setLoadWithOverviewMode(true);
webSettings.setUseWideViewPort(true);
webSettings.setSupportZoom(true);
webView.getSettings().setBuiltInZoomControls(false);
webView.getSettings().setDisplayZoomControls(false);
webSettings.setLayoutAlgorithm(WebSettings.LayoutAlgorithm.NARROW_COLUMNS);
webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
webSettings.setDomStorageEnabled(true);
webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
webView.setScrollbarFadingEnabled(true);
webView.getSettings().setRenderPriority(WebSettings.RenderPriority.HIGH);
webView.getSettings().setAppCacheEnabled(true);
webSettings.setSavePassword(true);
webSettings.setSaveFormData(true);
webSettings.setEnableSmoothTransition(true);
if (Build.VERSION.SDK_INT >= 19) {
webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
}
else if(Build.VERSION.SDK_INT >=11 && Build.VERSION.SDK_INT < 19) {
webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}
//end of performance improvement code
webSettings.setLoadWithOverviewMode(true);
webSettings.setAllowFileAccess(true);
webView.setWebViewClient(new Client());
webView.setWebChromeClient(new ChromeClient());
}
private File createImageFile() throws IOException {
// Create an image file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES);
File imageFile = File.createTempFile(
imageFileName, /* prefix */
".jpg", /* suffix */
storageDir /* directory */
);
return imageFile;
}
public class ChromeClient extends WebChromeClient {
// For Android 5.0
public boolean onShowFileChooser(WebView view, ValueCallback<Uri[]> filePath, WebChromeClient.FileChooserParams fileChooserParams) {
// Double check that we don't have any existing callbacks
if (mFilePathCallback != null) {
mFilePathCallback.onReceiveValue(null);
}
mFilePathCallback = filePath;
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile = null;
try {
photoFile = createImageFile();
takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
} catch (IOException ex) {
// Error occurred while creating the File
Log.e(TAG, "Unable to create Image File", ex);
}
// Continue only if the File was successfully created
if (photoFile != null) {
mCameraPhotoPath = "file:" + photoFile.getAbsolutePath();
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,
Uri.fromFile(photoFile));
} else {
takePictureIntent = null;
}
}
Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
contentSelectionIntent.setType("image/*");
Intent[] intentArray;
if (takePictureIntent != null) {
intentArray = new Intent[]{takePictureIntent};
} else {
intentArray = new Intent[0];
}
Intent chooserIntent = new Intent(Intent.ACTION_CHOOSER);
chooserIntent.putExtra(Intent.EXTRA_INTENT, contentSelectionIntent);
chooserIntent.putExtra(Intent.EXTRA_TITLE, "Image Chooser");
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, intentArray);
startActivityForResult(chooserIntent, INPUT_FILE_REQUEST_CODE);
return true;
}
// openFileChooser for Android 3.0+
public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType) {
mUploadMessage = uploadMsg;
// Create AndroidExampleFolder at sdcard
// Create AndroidExampleFolder at sdcard
File imageStorageDir = new File(
Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES)
, "AndroidExampleFolder");
if (!imageStorageDir.exists()) {
// Create AndroidExampleFolder at sdcard
imageStorageDir.mkdirs();
}
// Create camera captured image file path and name
File file = new File(
imageStorageDir + File.separator + "IMG_"
+ String.valueOf(System.currentTimeMillis())
+ ".jpg");
mCapturedImageURI = Uri.fromFile(file);
// Camera capture image intent
final Intent captureIntent = new Intent(
android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
captureIntent.putExtra(MediaStore.EXTRA_OUTPUT, mCapturedImageURI);
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
// Create file chooser intent
Intent chooserIntent = Intent.createChooser(i, "Image Chooser");
// Set camera intent to file chooser
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS
, new Parcelable[] { captureIntent });
// On select image call onActivityResult method of activity
startActivityForResult(chooserIntent, FILECHOOSER_RESULTCODE);
}
// openFileChooser for Android < 3.0
public void openFileChooser(ValueCallback<Uri> uploadMsg) {
openFileChooser(uploadMsg, "");
}
//openFileChooser for other Android versions
public void openFileChooser(ValueCallback<Uri> uploadMsg,
String acceptType,
String capture) {
openFileChooser(uploadMsg, acceptType);
}
}
public boolean onKeyDown(int keyCode, KeyEvent event) {
// Check if the key event was the Back button and if there's history
if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
webView.goBack();
return true;
}
// If it wasn't the Back key or there's no web page history, bubble up to the default
// system behavior (probably exit the activity)
return super.onKeyDown(keyCode, event);
}
public class Client extends WebViewClient {
ProgressDialog progressDialog;
public boolean shouldOverrideUrlLoading(WebView view, String url) {
// If url contains mailto link then open Mail Intent
if (url.contains("mailto:")) {
// Could be cleverer and use a regex
//Open links in new browser
view.getContext().startActivity(
new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
// Here we can open new activity
return true;
}else {
// Stay within this webview and load url
view.loadUrl(url);
return true;
}
}
//Show loader on url load
public void onPageStarted(WebView view, String url, Bitmap favicon) {
// Then show progress Dialog
// in standard case YourActivity.this
// if (progressDialog == null) {
// progressDialog = new ProgressDialog(MainActivity.this);
// progressDialog.setMessage("Loading...");
// progressDialog.show();
// }
//view.setVisibility(webView.INVISIBLE);
}
// Called when all page resources loaded
public void onPageFinished(WebView view, String url) {
try {
// Close progressDialog
// if (progressDialog.isShowing()) {
// progressDialog.dismiss();
// progressDialog = null;
// }
// spinner.setVisibility(View.GONE);
//
// view.setVisibility(webView.VISIBLE);
// super.onPageFinished(view, url);
swipe.setRefreshing(false);
if (findViewById(R.id.splach_screen).getVisibility() == View.VISIBLE) {
// show webview
findViewById(R.id.swipe).setVisibility(View.VISIBLE);
// hide splash screen
findViewById(R.id.splach_screen).setVisibility(View.GONE);
}
} catch (Exception exception) {
exception.printStackTrace();
}
}
}
}
衷心感谢您的帮助。很抱歉，我无法共享指向我们网站的链接，因为该公司处于发布前阶段，并且我们不允许共享此信息
非常感谢。