Android 从SD卡获取图像，压缩它，然后将其保存回SD？

我正在尝试从相机中捕获图像，如果图像太大，我想压缩位图并将其发送回sd卡。起初，我试图将图像直接拉入内存，但显然，根据我对上一个问题的回答，我可以做到：

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如何将该图像文件恢复到我的应用程序内存中？

您从相机获取的图像已压缩为jpeg格式。您将永远无法从相机获得原始图像。

您可以使用下面的代码重新缩放图像

Bitmap yourBitmap;
Bitmap resized = Bitmap.createScaledBitmap(yourBitmap, newWidth, newHeight, true);

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这会将图像压缩到更小的尺寸，您只需根据需要提供新的高度和宽度。

单击按钮调用方法将图像保存到SD卡：

SaveImage(bitmap);

private void SaveImage(Bitmap finalBitmap) {

  String root = Environment.getExternalStorageDirectory().toString();
  File myDir = new File(root + "/demo_images");    
  myDir.mkdirs();
  Random generator = new Random();
  int n = 10000;
  n = generator.nextInt(n);
  fname = "Image-"+ n +".jpg";
  File file = new File (myDir, fname);
// Below code will give you full path in TextView

> txtPath1.setText(file.getAbsolutePath());

  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();
  }
}

Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
imageview.setImageDrawable(bitmap);

将图像保存到SD卡：

SaveImage(bitmap);

private void SaveImage(Bitmap finalBitmap) {

  String root = Environment.getExternalStorageDirectory().toString();
  File myDir = new File(root + "/demo_images");    
  myDir.mkdirs();
  Random generator = new Random();
  int n = 10000;
  n = generator.nextInt(n);
  fname = "Image-"+ n +".jpg";
  File file = new File (myDir, fname);
// Below code will give you full path in TextView

> txtPath1.setText(file.getAbsolutePath());

  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();
  }
}

Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
imageview.setImageDrawable(bitmap);

用于从SD卡获取图像：

SaveImage(bitmap);

private void SaveImage(Bitmap finalBitmap) {

  String root = Environment.getExternalStorageDirectory().toString();
  File myDir = new File(root + "/demo_images");    
  myDir.mkdirs();
  Random generator = new Random();
  int n = 10000;
  n = generator.nextInt(n);
  fname = "Image-"+ n +".jpg";
  File file = new File (myDir, fname);
// Below code will give you full path in TextView

> txtPath1.setText(file.getAbsolutePath());

  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();
  }
}

Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
imageview.setImageDrawable(bitmap);

用于将图像存储到内存：

SaveImage(bitmap);

private void SaveImage(Bitmap finalBitmap) {

  String root = Environment.getExternalStorageDirectory().toString();
  File myDir = new File(root + "/demo_images");    
  myDir.mkdirs();
  Random generator = new Random();
  int n = 10000;
  n = generator.nextInt(n);
  fname = "Image-"+ n +".jpg";
  File file = new File (myDir, fname);
// Below code will give you full path in TextView

> txtPath1.setText(file.getAbsolutePath());

  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();
  }
}

Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
imageview.setImageDrawable(bitmap);