使用webview下载文件

Question

我想用webview下载文件，但是只要我点击下载链接，应用程序就会自动关闭。

mWebView.setDownloadListener(new DownloadListener() {
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
Request request = new Request( Uri.parse(url)); request.allowScanningByMediaScanner();
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download");
DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
dm.enqueue(request);

}});

Answer 1

public class MainActivity extends AppCompatActivity {
private WebView webView;
private String WebUrl = "https://www.google.com";
String FileName;
String  URL;
String Agent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webView = findViewById(R.id.webview);
webView.setWebChromeClient(new WebChromeClient());
webView.setWebViewClient(new WebViewClient());
webView.loadUrl(WebUrl);
webView.setDownloadListener(new DownloadListener() {
@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
FileName = URLUtil.guessFileName(url, contentDisposition, getType(url));
URL = url;
Agent = userAgent;
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
startDownload(FileName, URL, Agent);
}else {
requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1001);
}
}else {
startDownload(FileName, URL, Agent);
}
}
});
}
private void startDownload(String filename, String url, String userAgent) {
try {
DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
String cookie = CookieManager.getInstance().getCookie(url);
request.setTitle(filename)
.setDescription("Downloading")
.setMimeType(getType(url))
.setAllowedOverMetered(true)
.setAllowedOverRoaming(true)
.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE | DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, filename);
dm.enqueue(request);
Toast.makeText(this, "Download Started", Toast.LENGTH_SHORT).show();
FileName = "";
URL = "";
Agent = "";
}catch (Exception e) {
Toast.makeText(this, "Error Occured : "+e, Toast.LENGTH_SHORT).show();
}
}
private String getType(String link) {
ContentResolver cr = getContentResolver();
MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
return mimeTypeMap.getExtensionFromMimeType(cr.getType(Uri.parse(link)));
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(requestCode == 1001) {
if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if(!FileName.equals("") && !URL.equals("") && !Agent.equals("")){
startDownload(FileName, URL, Agent);
}
}
}
}
}