uri以content开始,从uri获取文件路径

private String getRealPathFromURI(Uri contentUri) {
String[] proj = { MediaStore.Images.Media.DATA };
CursorLoader loader = new CursorLoader(getApplicationContext(),
contentUri, proj, null, null, null);
Cursor cursor = loader.loadInBackground();
int column_index = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}