我有一个网站正尝试使用android studio转换为android应用，所有内容在网络上都运行良好，用户可以在将图片发送到服务器之前对其进行预览。将网站转换为android应用后，预览版无法在android上运行...下面是在android studio中运行的代码，用于转换网站...我将非常高兴获得任何帮助和代码...预览从API级别15到API级别28
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.ActivityNotFoundException;
import android.graphics.Bitmap;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.webkit.ValueCallback;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
String websiteURL = "https://example.com"; // sets web url
private WebView webview;
SwipeRefreshLayout mySwipeRefreshLayout;
private ProgressBar progressBar;
private ValueCallback<Uri> mUploadMessage;
public ValueCallback<Uri[]> uploadMessage;
public static final int REQUEST_SELECT_FILE = 100;
private final static int FILECHOOSER_RESULTCODE = 1;
@Override
public void onActivityResult(int requestCode, int resultCode, Intent intent)
{
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
{
if (requestCode == REQUEST_SELECT_FILE)
{
if (uploadMessage == null)
return;
uploadMessage.onReceiveValue
(WebChromeClient.FileChooserParams.parseResult(resultCode, intent));
uploadMessage = null;
}
}
else if (requestCode == FILECHOOSER_RESULTCODE)
{
if (null == mUploadMessage)
return;
// Use MainActivity.RESULT_OK if you're implementing WebView inside Fragment
// Use RESULT_OK only if you're implementing WebView inside an Activity
Uri result = intent == null || resultCode != MainActivity.RESULT_OK ? null :
intent.getData();
mUploadMessage.onReceiveValue(result);
mUploadMessage = null;
}
else
Toast.makeText(getApplicationContext(), "Failed to Upload Image",
Toast.LENGTH_LONG).show();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if( ! CheckNetwork.isInternetAvailable(this)) //returns true if internet available
{
//if there is no internet do this
//setContentView(R.layout.activity_main);
//Toast.makeText(this,"No Internet Connection, Chris",Toast.LENGTH_LONG).show();
new AlertDialog.Builder(this) //alert the person knowing they are about to close
.setTitle("You need an internet connection to use this app")
.setMessage("Check to see if you're mobile data is on or you are connected to a wi-fi network.")
.setPositiveButton("Okay", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
})
//.setNegativeButton("No", null)
.show();
}
else
{
//Webview stuff
webview = findViewById(R.id.webView);
webview.getSettings().setJavaScriptEnabled(true);
webview.getSettings().setDomStorageEnabled(true);
webview.getSettings().setSupportZoom(false);
webview.getSettings().setAllowFileAccess(true);
webview.getSettings().setAllowContentAccess(true);
webview.setOverScrollMode(WebView.OVER_SCROLL_NEVER);
webview.loadUrl(websiteURL);
webview.setWebViewClient(new WebViewClientDemo());
webview.setWebChromeClient(new WebChromeClient()
{
// For 3.0+ Devices (Start)
// onActivityResult attached before constructor
protected void openFileChooser(ValueCallback uploadMsg, String acceptType)
{
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
startActivityForResult(Intent.createChooser(i, "File Browser"),
FILECHOOSER_RESULTCODE);
}
// For Lollipop 5.0+ Devices
public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]>
filePathCallback, WebChromeClient.FileChooserParams fileChooserParams)
{
if (uploadMessage != null) {
uploadMessage.onReceiveValue(null);
uploadMessage = null;
}
uploadMessage = filePathCallback;
Intent intent = fileChooserParams.createIntent();
try
{
startActivityForResult(intent, REQUEST_SELECT_FILE);
} catch (ActivityNotFoundException e)
{
uploadMessage = null;
Toast.makeText(getApplicationContext(), "Cannot Open File Chooser",
Toast.LENGTH_LONG).show();
return false;
}
return true;
}
//For Android 4.1 only
protected void openFileChooser(ValueCallback<Uri> uploadMsg, String
acceptType, String capture)
{
mUploadMessage = uploadMsg;
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("image/*");
startActivityForResult(Intent.createChooser(intent, "File Browser"),
FILECHOOSER_RESULTCODE);
}
protected void openFileChooser(ValueCallback<Uri> uploadMsg)
{
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
startActivityForResult(Intent.createChooser(i, "File Chooser"),
FILECHOOSER_RESULTCODE);
}
});
}
//Swipe to refresh functionality
mySwipeRefreshLayout = this.findViewById(R.id.swipeContainer);
mySwipeRefreshLayout.setOnRefreshListener(
new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
webview.reload();
}
}
);
//Progress bar variables
progressBar = findViewById(R.id.progressBar);
progressBar.setMax(100);
}
private class WebViewClientDemo extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
@Override
public void onPageFinished(WebView view, String url) {
super.onPageFinished(view, url);
progressBar.setVisibility(View.GONE);
progressBar.setProgress(100);
mySwipeRefreshLayout.setRefreshing(false);
}
@Override
public void onPageStarted(WebView view, String url, Bitmap favicon) {
super.onPageStarted(view, url, favicon);
progressBar.setVisibility(View.VISIBLE);
progressBar.setProgress(0);
}
}
private class WebChromeClientDemo extends WebChromeClient {
public void onProgressChanged(WebView view, int progress) {
progressBar.setProgress(progress);
}
}
//set back button functionality
@Override
public void onBackPressed() { //if user presses the back button do this
if (webview.isFocused() && webview.canGoBack()) { //check if in webview and the user can go back
webview.goBack(); //go back in webview
} else { //do this if the webview cannot go back any further
new AlertDialog.Builder(this) //alert the person knowing they are about to close
.setTitle("You are about to close the application")
.setMessage("You cannot go back any further, would you like to close?")
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
})
.setNegativeButton("No", null)
.show();
}
}
}
class CheckNetwork {
private static final String TAG = CheckNetwork.class.getSimpleName();
public static boolean isInternetAvailable(Context context)
{
NetworkInfo info = (NetworkInfo) ((ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo();
if (info == null)
{
Log.d(TAG,"no internet connection");
return false;
}
else
{
if(info.isConnected())
{
Log.d(TAG," internet connection available...");
return true;
}
else
{
Log.d(TAG," internet connection");
return true;
}
}
}
}