String filename = "MyApp/MediaTag/MediaTag-"+objectId+".png";
File file = new File(Environment.getExternalStorageDirectory(), filename);
FileOutputStream fos;
fos = new FileOutputStream(file);
fos.write(mediaTagBuffer);
fos.flush();
fos.close();
但是它抛出了一个异常： .FileNotFoundException：/mnt/sdcard/MyApp/MediaCard/MediaCard-0.png（没有此类文件或目录）
在该行上：
fos = new FileOutputStream(file); 如果我将文件名设置为：
"MyApp/MediaTag-"+objectId+"可以正常工作，但是如果我尝试创建文件并将其保存到另一个目录，则会引发异常。那么有什么想法我做错了吗？另一个问题：有什么方法可以将我的文件设置为外部存储的私有文件，以便用户只有在连接设备后才能在图库中看到它们如
Disk Drive吗？#1 楼
使用此功能将位图保存在SD卡中private void SaveImage(Bitmap finalBitmap) {
String root = Environment.getExternalStorageDirectory().toString();
File myDir = new File(root + "/saved_images");
if (!myDir.exists()) {
myDir.mkdirs();
}
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
String fname = "Image-"+ n +".jpg";
File file = new File (myDir, fname);
if (file.exists ())
file.delete ();
try {
FileOutputStream out = new FileOutputStream(file);
finalBitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
}
并将其添加到清单中
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
编辑：使用此行，您将可以在画廊视图中查看保存的图像。
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://" + Environment.getExternalStorageDirectory())));
也请参见此链接http://rajareddypolam.wordpress.com/ ？p = 3＆preview = true
#2 楼
RajaReddy提供的代码不再适用于KitKat此代码可以（2个更改）：
private void saveImageToExternalStorage(Bitmap finalBitmap) {
String root = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).toString();
File myDir = new File(root + "/saved_images");
myDir.mkdirs();
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
String fname = "Image-" + n + ".jpg";
File file = new File(myDir, fname);
if (file.exists())
file.delete();
try {
FileOutputStream out = new FileOutputStream(file);
finalBitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
out.flush();
out.close();
}
catch (Exception e) {
e.printStackTrace();
}
// Tell the media scanner about the new file so that it is
// immediately available to the user.
MediaScannerConnection.scanFile(this, new String[] { file.toString() }, null,
new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
Log.i("ExternalStorage", "Scanned " + path + ":");
Log.i("ExternalStorage", "-> uri=" + uri);
}
});
}
评论
我正在获取uri null？
– Mukesh
17-10-12在10:25
告诉媒体扫描器有关新文件的信息，以便用户可以立即使用它-节省了我的时间
–Saiful Islam Sajib
18/12/11在4:24
#3 楼
Update 2018，SDK> = 23.现在您还应该使用以下方法检查用户是否已授予对外部存储的权限：
public boolean isStoragePermissionGranted() {
String TAG = "Storage Permission";
if (Build.VERSION.SDK_INT >= 23) {
if (this.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
== PackageManager.PERMISSION_GRANTED) {
Log.v(TAG, "Permission is granted");
return true;
} else {
Log.v(TAG, "Permission is revoked");
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
return false;
}
}
else { //permission is automatically granted on sdk<23 upon installation
Log.v(TAG,"Permission is granted");
return true;
}
}
public void saveImageBitmap(Bitmap image_bitmap, String image_name) {
String root = Environment.getExternalStorageDirectory().toString();
if (isStoragePermissionGranted()) { // check or ask permission
File myDir = new File(root, "/saved_images");
if (!myDir.exists()) {
myDir.mkdirs();
}
String fname = "Image-" + image_name + ".jpg";
File file = new File(myDir, fname);
if (file.exists()) {
file.delete();
}
try {
file.createNewFile(); // if file already exists will do nothing
FileOutputStream out = new FileOutputStream(file);
image_bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
MediaScannerConnection.scanFile(this, new String[]{file.toString()}, new String[]{file.getName()}, null);
}
}
并且当然要添加
AndroidManifest.xml：<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
#4 楼
您需要为此权限<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
和方法：
public boolean saveImageOnExternalData(String filePath, byte[] fileData) {
boolean isFileSaved = false;
try {
File f = new File(filePath);
if (f.exists())
f.delete();
f.createNewFile();
FileOutputStream fos = new FileOutputStream(f);
fos.write(fileData);
fos.flush();
fos.close();
isFileSaved = true;
// File Saved
} catch (FileNotFoundException e) {
System.out.println("FileNotFoundException");
e.printStackTrace();
} catch (IOException e) {
System.out.println("IOException");
e.printStackTrace();
}
return isFileSaved;
// File Not Saved
}
#5 楼
确保您的应用具有允许写入外部存储的适当权限：http://developer.android.com/reference/android/Manifest.permission.html#WRITE_EXTERNAL_STORAGE它应该看起来像在清单文件中是这样的：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
#6 楼
尝试一下：检查外部存储设备
写入文件
读取文件
public class WriteSDCard extends Activity {
private static final String TAG = "MEDIA";
private TextView tv;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tv = (TextView) findViewById(R.id.TextView01);
checkExternalMedia();
writeToSDFile();
readRaw();
}
/**
* Method to check whether external media available and writable. This is
* adapted from
* http://developer.android.com/guide/topics/data/data-storage.html
* #filesExternal
*/
private void checkExternalMedia() {
boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// Can read and write the media
mExternalStorageAvailable = mExternalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
// Can only read the media
mExternalStorageAvailable = true;
mExternalStorageWriteable = false;
} else {
// Can't read or write
mExternalStorageAvailable = mExternalStorageWriteable = false;
}
tv.append("\n\nExternal Media: readable=" + mExternalStorageAvailable
+ " writable=" + mExternalStorageWriteable);
}
/**
* Method to write ascii text characters to file on SD card. Note that you
* must add a WRITE_EXTERNAL_STORAGE permission to the manifest file or this
* method will throw a FileNotFound Exception because you won't have write
* permission.
*/
private void writeToSDFile() {
// Find the root of the external storage.
// See http://developer.android.com/guide/topics/data/data-
// storage.html#filesExternal
File root = android.os.Environment.getExternalStorageDirectory();
tv.append("\nExternal file system root: " + root);
// See
// http://stackoverflow.com/questions/3551821/android-write-to-sd-card-folder
File dir = new File(root.getAbsolutePath() + "/download");
dir.mkdirs();
File file = new File(dir, "myData.txt");
try {
FileOutputStream f = new FileOutputStream(file);
PrintWriter pw = new PrintWriter(f);
pw.println("Hi , How are you");
pw.println("Hello");
pw.flush();
pw.close();
f.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
Log.i(TAG, "******* File not found. Did you"
+ " add a WRITE_EXTERNAL_STORAGE permission to the manifest?");
} catch (IOException e) {
e.printStackTrace();
}
tv.append("\n\nFile written to " + file);
}
/**
* Method to read in a text file placed in the res/raw directory of the
* application. The method reads in all lines of the file sequentially.
*/
private void readRaw() {
tv.append("\nData read from res/raw/textfile.txt:");
InputStream is = this.getResources().openRawResource(R.raw.textfile);
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr, 8192); // 2nd arg is buffer
// size
// More efficient (less readable) implementation of above is the
// composite expression
/*
* BufferedReader br = new BufferedReader(new InputStreamReader(
* this.getResources().openRawResource(R.raw.textfile)), 8192);
*/
try {
String test;
while (true) {
test = br.readLine();
// readLine() returns null if no more lines in the file
if (test == null) break;
tv.append("\n" + " " + test);
}
isr.close();
is.close();
br.close();
} catch (IOException e) {
e.printStackTrace();
}
tv.append("\n\nThat is all");
}
}
评论
这看起来与此处的代码非常相似：stackoverflow.com/a/8330635/19679。如果是从那里提取的，那么您可能应该在答案中引用它。
–布拉德·拉森♦
2014年5月29日17:17
#7 楼
我创建了一个用于保存位图的AsyncTask。public class BitmapSaver extends AsyncTask<Void, Void, Void>
{
public static final String TAG ="BitmapSaver";
private Bitmap bmp;
private Context ctx;
private File pictureFile;
public BitmapSaver(Context paramContext , Bitmap paramBitmap)
{
ctx = paramContext;
bmp = paramBitmap;
}
/** Create a File for saving an image or video */
private File getOutputMediaFile()
{
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStorageDirectory()
+ "/Android/data/"
+ ctx.getPackageName()
+ "/Files");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("ddMMyyyy_HHmm").format(new Date());
File mediaFile;
String mImageName="MI_"+ timeStamp +".jpg";
mediaFile = new File(mediaStorageDir.getPath() + File.separator + mImageName);
return mediaFile;
}
protected Void doInBackground(Void... paramVarArgs)
{
this.pictureFile = getOutputMediaFile();
if (this.pictureFile == null) { return null; }
try
{
FileOutputStream localFileOutputStream = new FileOutputStream(this.pictureFile);
this.bmp.compress(Bitmap.CompressFormat.PNG, 90, localFileOutputStream);
localFileOutputStream.close();
}
catch (FileNotFoundException localFileNotFoundException)
{
return null;
}
catch (IOException localIOException)
{
}
return null;
}
protected void onPostExecute(Void paramVoid)
{
super.onPostExecute(paramVoid);
try
{
//it will help you broadcast and view the saved bitmap in Gallery
this.ctx.sendBroadcast(new Intent("android.intent.action.MEDIA_MOUNTED", Uri
.parse("file://" + Environment.getExternalStorageDirectory())));
Toast.makeText(this.ctx, "File saved", 0).show();
return;
}
catch (Exception localException1)
{
try
{
Context localContext = this.ctx;
String[] arrayOfString = new String[1];
arrayOfString[0] = this.pictureFile.toString();
MediaScannerConnection.scanFile(localContext, arrayOfString, null,
new MediaScannerConnection.OnScanCompletedListener()
{
public void onScanCompleted(String paramAnonymousString ,
Uri paramAnonymousUri)
{
}
});
return;
}
catch (Exception localException2)
{
}
}
}
}
评论
我如何保存gif图像？
– Vishal Senjaliya
16-10-3在10:10
Gif图片包含多张图片。您必须先将这些帧分开，然后才能使用此方法。这是我的意见。
– AndroidGeek
16-10-10在6:02
我是从stackoverflow.com/questions/39826400/…做到的
– Vishal Senjaliya
16-10-10在6:19
#8 楼
可能由于没有MediaCard子目录而引发异常。您应该检查路径中是否所有目录都存在。关于文件的可见性：如果将名为
.nomedia的文件放在目录中，则表示您不希望Android对其进行媒体扫描文件，它们将不会出现在图库中。#9 楼
由于android 4.4文件保存已更改。有ContextCompat.getExternalFilesDirs(context, name);
它重新调整数组。
当名称为空时
第一个值类似于/storage/emulated/0/Android/com.my.package/files
第二个值类似于
/storage/extSdCard/Android/com.my.package/files
的一部分小小的凌乱代码，但演示了它的工作原理：
/** Create a File for saving an image or video
* @throws Exception */
private File getOutputMediaFile(int type) throws Exception{
// Check that the SDCard is mounted
File mediaStorageDir;
if(internalstorage.isChecked())
{
mediaStorageDir = new File(getFilesDir().getAbsolutePath() );
}
else
{
File[] dirs=ContextCompat.getExternalFilesDirs(this, null);
mediaStorageDir = new File(dirs[dirs.length>1?1:0].getAbsolutePath() );
}
// Create the storage directory(MyCameraVideo) if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
output.setText("Failed to create directory.");
Toast.makeText(this, "Failed to create directory.", Toast.LENGTH_LONG).show();
Log.d("myapp", "Failed to create directory");
return null;
}
}
// Create a media file name
// For unique file name appending current timeStamp with file name
java.util.Date date= new java.util.Date();
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss",Locale.ENGLISH) .format(date.getTime());
File mediaFile;
if(type == MEDIA_TYPE_VIDEO) {
// For unique video file name appending current timeStamp with file name
mediaFile = new File(mediaStorageDir.getPath() + File.separator + slpid + "_" + pwsid + "_" + timeStamp + ".mp4");
}
else if(type == MEDIA_TYPE_AUDIO) {
// For unique video file name appending current timeStamp with file name
mediaFile = new File(mediaStorageDir.getPath() + File.separator + slpid + "_" + pwsid + "_" + timeStamp + ".3gp");
} else {
return null;
}
return mediaFile;
}
/** Create a file Uri for saving an image or video
* @throws Exception */
private Uri getOutputMediaFileUri(int type) throws Exception{
return Uri.fromFile(getOutputMediaFile(type));
}
//usage:
try {
file=getOutputMediaFileUri(MEDIA_TYPE_AUDIO).getPath();
} catch (Exception e1) {
e1.printStackTrace();
return;
}
#10 楼
对于API级别23（棉花糖）及更高版本，除了清单中的uses-permission外，还应该实现弹出权限，并且用户需要在运行时使用该应用时授予它。下面，有一个示例将
hello world!保存为图片目录内myFile.txt目录中Test文件的内容。清单中：
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
其中您要创建文件：
int permission = ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
String[] PERMISSIONS_STORAGE = {Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
if (permission != PackageManager.PERMISSION_GRANTED)
{
ActivityCompat.requestPermissions(MainActivity.this,PERMISSIONS_STORAGE, 1);
}
File myDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "Test");
myDir.mkdirs();
try
{
String FILENAME = "myFile.txt";
File file = new File (myDir, FILENAME);
String string = "hello world!";
FileOutputStream fos = new FileOutputStream(file);
fos.write(string.getBytes());
fos.close();
}
catch (IOException e) {
e.printStackTrace();
}
#11 楼
这段代码在KitKat上也很好用。赞赏@RajaReddy PolamReddy在这里添加了一些步骤，并且还在Gallery上可见。 >
public void SaveOnClick(View v){
File mainfile;
String fpath;
try {
//i.e v2:My view to save on own folder
v2.setDrawingCacheEnabled(true);
//Your final bitmap according to my code.
bitmap_tmp = v2.getDrawingCache();
File(getExternalFilesDir(Environment.DIRECTORY_PICTURES)+File.separator+"/MyFolder");
Random random=new Random();
int ii=100000;
ii=random.nextInt(ii);
String fname="MyPic_"+ ii + ".jpg";
File direct = new File(Environment.getExternalStorageDirectory() + "/MyFolder");
if (!direct.exists()) {
File wallpaperDirectory = new File("/sdcard/MyFolder/");
wallpaperDirectory.mkdirs();
}
mainfile = new File(new File("/sdcard/MyFolder/"), fname);
if (mainfile.exists()) {
mainfile.delete();
}
FileOutputStream fileOutputStream;
fileOutputStream = new FileOutputStream(mainfile);
bitmap_tmp.compress(CompressFormat.JPEG, 100, fileOutputStream);
Toast.makeText(MyActivity.this.getApplicationContext(), "Saved in Gallery..", Toast.LENGTH_LONG).show();
fileOutputStream.flush();
fileOutputStream.close();
fpath=mainfile.toString();
galleryAddPic(fpath);
} catch(FileNotFoundException e){
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#12 楼
单击此处以获取完整的描述和源代码public void saveImage(Context mContext, Bitmap bitmapImage) {
File sampleDir = new File(Environment.getExternalStorageDirectory() + "/" + "ApplicationName");
TextView tvImageLocation = (TextView) findViewById(R.id.tvImageLocation);
tvImageLocation.setText("Image Store At : " + sampleDir);
if (!sampleDir.exists()) {
createpathForImage(mContext, bitmapImage, sampleDir);
} else {
createpathForImage(mContext, bitmapImage, sampleDir);
}
}
评论
在此处添加一些说明
–马修斯·桑尼
18-09-15在8:36
评论
您仍应使用Environment.getExternalStorageDirectory（）代替/ sdcard。
–车贾米
11-10-25在10:41
它仅保存在您的文件夹中，它显示在相机中表示您正在通过相机自动拍摄图像，它存储在相机中。
–RajaReddy PolamReddy
13年4月12日在11:43
请最终使用，不要捕获通用异常
– Mr_and_Mrs_D
13年7月28日在18:01
@LiamGeorgeBetsworth上面描述的所有行为均与KitKat之前的版本相同。
–穆罕默德·巴巴尔（Muhammad Babar）
2014年6月5日10:12
不适合使用Intent.ACTION_MEDIA_MOUNTED，并且在KitKat上不起作用。正确的广播意图是新的意图（Intent.ACTION_MEDIA_SCANNER_SCAN_FILE，Uri.fromFile（file））
– Anthony Garcia-Labiad
16年1月2日，18：52