Bitmap压缩图片

   代码实现：

public class MainActivity extends AppCompatActivity {

    private ImageView img;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        //从资源文件中得到图片
        Bitmap rawBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.abc);
        // 得到图片原始的高宽
        int rawHeight = rawBitmap.getHeight();
        int rawWidth = rawBitmap.getWidth();
        // 新建立矩阵
        Matrix matrix = new Matrix();
        matrix.postScale(0.2f, 0.2f);
        
        Bitmap newBitmap = Bitmap.createBitmap(rawBitmap, 0, 0, rawWidth, rawWidth, matrix, true);
        BitmapDrawable bitmapDrawable=new BitmapDrawable(newBitmap);
        img.setImageDrawable(bitmapDrawable);
    }

    private void initView() {
        img = (ImageView) findViewById(R.id.img);
    }
}