1. 首先，在XML布局文件中设置ImageView的scaleType为matrix，如下所示：

2. 在Java代码中，获取ImageView的宽度和高度，以及要缩放的目标宽度和高度：

ImageView imageView = (ImageView) findViewById(R.id.imageView);

int imageViewWidth = imageView.getWidth();
int imageViewHeight = imageView.getHeight();

int targetWidth = 500;
int targetHeight = 500;

3. 然后，计算出锚点的位置，即缩放的中心点位置坐标：

int anchorX = (int) (imageViewWidth * 0.5);
int anchorY = (int) (imageViewHeight * 0.5);

4. 接下来，创建一个Matrix对象，并调用postScale方法来实现缩放操作，以及postTranslate方法来实现平移操作：

Matrix matrix = new Matrix();
matrix.postScale((float) targetWidth / imageViewWidth, (float) targetHeight / imageViewHeight, anchorX, anchorY);
matrix.postTranslate((imageViewWidth - targetWidth) / 2, (imageViewHeight - targetHeight) / 2);

imageView.setImageMatrix(matrix);

完整的代码示例：

ImageView imageView = (ImageView) findViewById(R.id.imageView);

int imageViewWidth = imageView.getWidth();
int imageViewHeight = imageView.getHeight();

int targetWidth = 500;
int targetHeight = 500;

int anchorX = (int) (imageViewWidth * 0.5);
int anchorY = (int) (imageViewHeight * 0.5);

Matrix matrix = new Matrix();
matrix.postScale((float) targetWidth / imageViewWidth, (float) targetHeight / imageViewHeight, anchorX, anchorY);
matrix.postTranslate((imageViewWidth - targetWidth) / 2, (imageViewHeight - targetHeight) / 2);

imageView.setImageMatrix(matrix);