将位图转换为文件

试试这个:

bitmap.compress(Bitmap.CompressFormat.PNG, quality, outStream);

看这个

希望对你有所帮助:

//create a file to write bitmap data
File f = new File(context.getCacheDir(), filename);
f.createNewFile();


//Convert bitmap to byte array
Bitmap bitmap = your bitmap;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
byte[] bitmapdata = bos.toByteArray();


//write the bytes in file
FileOutputStream fos = new FileOutputStream(f);
fos.write(bitmapdata);
fos.flush();
fos.close();

File file = new File("path");
OutputStream os = new BufferedOutputStream(new FileOutputStream(file));
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);
os.close();

转换 Bitmap到 File需要在后台完成(不在主线程)它挂起的用户界面特别是如果 bitmap是大的

File file;


public class fileFromBitmap extends AsyncTask<Void, Integer, String> {


Context context;
Bitmap bitmap;
String path_external = Environment.getExternalStorageDirectory() + File.separator + "temporary_file.jpg";


public fileFromBitmap(Bitmap bitmap, Context context) {
this.bitmap = bitmap;
this.context= context;
}


@Override
protected void onPreExecute() {
super.onPreExecute();
// before executing doInBackground
// update your UI
// exp; make progressbar visible
}


@Override
protected String doInBackground(Void... params) {


ByteArrayOutputStream bytes = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
file = new File(Environment.getExternalStorageDirectory() + File.separator + "temporary_file.jpg");
try {
FileOutputStream fo = new FileOutputStream(file);
fo.write(bytes.toByteArray());
fo.flush();
fo.close();
} catch (IOException e) {
e.printStackTrace();
}


return null;
}




@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
// back to main thread after finishing doInBackground
// update your UI or take action after
// exp; make progressbar gone


sendFile(file);


}
}

就这么定了

new fileFromBitmap(my_bitmap, getApplicationContext()).execute();

你必须使用 onPostExecute中的 file。

更改存储在缓存中的 file目录 替换线:

 file = new File(Environment.getExternalStorageDirectory() + File.separator + "temporary_file.jpg");

与:

file  = new File(context.getCacheDir(), "temporary_file.jpg");

希望这能帮到你

类 MainActivity: AppCompatActivity (){

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)


// Get the bitmap from assets and display into image view
val bitmap = assetsToBitmap("tulip.jpg")
// If bitmap is not null
bitmap?.let {
image_view_bitmap.setImageBitmap(bitmap)
}




// Click listener for button widget
button.setOnClickListener{
if(bitmap!=null){
// Save the bitmap to a file and display it into image view
val uri = bitmapToFile(bitmap)
image_view_file.setImageURI(uri)


// Display the saved bitmap's uri in text view
text_view.text = uri.toString()


// Show a toast message
toast("Bitmap saved in a file.")
}else{
toast("bitmap not found.")
}
}
}




// Method to get a bitmap from assets
private fun assetsToBitmap(fileName:String):Bitmap?{
return try{
val stream = assets.open(fileName)
BitmapFactory.decodeStream(stream)
}catch (e:IOException){
e.printStackTrace()
null
}
}




// Method to save an bitmap to a file
private fun bitmapToFile(bitmap:Bitmap): Uri {
// Get the context wrapper
val wrapper = ContextWrapper(applicationContext)


// Initialize a new file instance to save bitmap object
var file = wrapper.getDir("Images",Context.MODE_PRIVATE)
file = File(file,"${UUID.randomUUID()}.jpg")


try{
// Compress the bitmap and save in jpg format
val stream:OutputStream = FileOutputStream(file)
bitmap.compress(Bitmap.CompressFormat.JPEG,100,stream)
stream.flush()
stream.close()
}catch (e:IOException){
e.printStackTrace()
}


// Return the saved bitmap uri
return Uri.parse(file.absolutePath)
}

}

大多数答案都太长或太短，没有达到目的。对于那些如何寻找 Java 或 Kotlin 代码转换位图文件对象。下面是我写的关于这个主题的详细文章。在 Android 中将位图转换为文件

public static File bitmapToFile(Context context,Bitmap bitmap, String fileNameToSave) { // File name like "image.png"
//create a file to write bitmap data
File file = null;
try {
file = new File(Environment.getExternalStorageDirectory() + File.separator + fileNameToSave);
file.createNewFile();


//Convert bitmap to byte array
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 0 , bos); // YOU can also save it in JPEG
byte[] bitmapdata = bos.toByteArray();


//write the bytes in file
FileOutputStream fos = new FileOutputStream(file);
fos.write(bitmapdata);
fos.flush();
fos.close();
return file;
}catch (Exception e){
e.printStackTrace();
return file; // it will return null
}
}