如何从现有的URI中保存媒体文件（比如.mp3），这是我从隐含意图获得的？
使用这种方法，它的工作原理
void savefile(URI sourceuri)
{
String sourceFilename= sourceuri.getPath();
String destinationFilename = android.os.Environment.getExternalStorageDirectory().getPath()+File.separatorChar+"abc.mp3";
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
try {
bis = new BufferedInputStream(new FileInputStream(sourceFilename));
bos = new BufferedOutputStream(new FileOutputStream(destinationFilename, false));
byte[] buf = new byte[1024];
bis.read(buf);
do {
bos.write(buf);
} while(bis.read(buf) != -1);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (bis != null) bis.close();
if (bos != null) bos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private static String FILE_NAM = "video";
String outputfile = getFilesDir() + File.separator+FILE_NAM+"_tmp.mp4";
InputStream in = getContentResolver().openInputStream(videoFileUri);
private static File createFileFromInputStream(InputStream inputStream, String fileName) {
try{
File f = new File(fileName);
f.setWritable(true, false);
OutputStream outputStream = new FileOutputStream(f);
byte buffer[] = new byte[1024];
int length = 0;
while((length=inputStream.read(buffer)) > 0) {
outputStream.write(buffer,0,length);
}
outputStream.close();
inputStream.close();
return f;
}catch (IOException e) {
System.out.println("error in creating a file");
e.printStackTrace();
}
return null;
}
如果从Google云端硬盘收到Uri，它也可以是虚拟文件Uri。来自CommonsWare的Check this文章了解更多信息。所以你在从Uri保存文件时也必须考虑这个条件。
要查找文件Uri是否为虚拟，您可以使用
private static boolean isVirtualFile(Context context, Uri uri) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
if (!DocumentsContract.isDocumentUri(context, uri)) {
return false;
}
Cursor cursor = context.getContentResolver().query(
uri,
new String[]{DocumentsContract.Document.COLUMN_FLAGS},
null, null, null);
int flags = 0;
if (cursor.moveToFirst()) {
flags = cursor.getInt(0);
}
cursor.close();
return (flags & DocumentsContract.Document.FLAG_VIRTUAL_DOCUMENT) != 0;
} else {
return false;
}
}
您可以从此虚拟文件中获取流数据，如下所示：
private static InputStream getInputStreamForVirtualFile(Context context, Uri uri, String mimeTypeFilter)
throws IOException {
ContentResolver resolver = context.getContentResolver();
String[] openableMimeTypes = resolver.getStreamTypes(uri, mimeTypeFilter);
if (openableMimeTypes == null || openableMimeTypes.length < 1) {
throw new FileNotFoundException();
}
return resolver
.openTypedAssetFileDescriptor(uri, openableMimeTypes[0], null)
.createInputStream();
}
寻找MIME类型试试
private static String getMimeType(String url) {
String type = null;
String extension = MimeTypeMap.getFileExtensionFromUrl(url);
if (extension != null) {
type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
}
return type;
}
总的来说，你可以使用
public static boolean saveFile(Context context, String name, Uri sourceuri, String destinationDir, String destFileName) {
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
InputStream input = null;
boolean hasError = false;
try {
if (isVirtualFile(context, sourceuri)) {
input = getInputStreamForVirtualFile(context, sourceuri, getMimeType(name));
} else {
input = context.getContentResolver().openInputStream(sourceuri);
}
boolean directorySetupResult;
File destDir = new File(destinationDir);
if (!destDir.exists()) {
directorySetupResult = destDir.mkdirs();
} else if (!destDir.isDirectory()) {
directorySetupResult = replaceFileWithDir(destinationDir);
} else {
directorySetupResult = true;
}
if (!directorySetupResult) {
hasError = true;
} else {
String destination = destinationDir + File.separator + destFileName;
int originalsize = input.available();
bis = new BufferedInputStream(input);
bos = new BufferedOutputStream(new FileOutputStream(destination));
byte[] buf = new byte[originalsize];
bis.read(buf);
do {
bos.write(buf);
} while (bis.read(buf) != -1);
}
} catch (Exception e) {
e.printStackTrace();
hasError = true;
} finally {
try {
if (bos != null) {
bos.flush();
bos.close();
}
} catch (Exception ignored) {
}
}
return !hasError;
}
private static boolean replaceFileWithDir(String path) {
File file = new File(path);
if (!file.exists()) {
if (file.mkdirs()) {
return true;
}
} else if (file.delete()) {
File folder = new File(path);
if (folder.mkdirs()) {
return true;
}
}
return false;
}
从异步任务调用此方法。如果这有帮助，请告诉我。
1.从URI路径创建文件：
File from = new File(uri.toString());
2.创建另一个文件，将文件保存为：
File to = new File("target file path");
3.将文件重命名为：
from.renameTo(to);
这样，默认路径中的文件将自动删除并在新路径中创建。
这是最简单，最干净的：
private void saveFile(Uri sourceUri, File destination)
try {
File source = new File(sourceUri.getPath());
FileChannel src = new FileInputStream(source).getChannel();
FileChannel dst = new FileOutputStream(destination).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
从外部源接收android.net.Uri时，保存文件的最佳方法是从流中：
try (InputStream ins = activity.getContentResolver().openInputStream(source_uri)) {
File dest = new File(destination_path);
createFileFromStream(ins, dest);
} catch (Exception ex) {
Log.e("Save File", ex.getMessage());
ex.printStackTrace();
}
createFileFromStream方法：
public static void createFileFromStream(InputStream ins, File destination) {
try (OutputStream os = new FileOutputStream(destination)) {
byte[] buffer = new byte[4096];
int length;
while ((length = ins.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
os.flush();
} catch (Exception ex) {
Log.e("Save File", ex.getMessage());
ex.printStackTrace();
}
}