Android 加载压缩的图片

/**
* 压缩图片
* @author chen.lin
*
*/
public class LoadImageActivity extends Activity implements OnClickListener {
private Button mBtnLoad;
private ImageView mImageView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_load);

initViews();
}

private void initViews() {
mBtnLoad = (Button) findViewById(R.id.btnLoadImage);
mImageView = (ImageView) findViewById(R.id.imageView);

mBtnLoad.setOnClickListener(this);
}

@Override
public void onClick(View v) {
if (v == mBtnLoad) {
Options options = new Options();
BitmapFactory.decodeFile("/sdcard/images/1.jpg", options);
//不去真的解析图片，只是获取图片的头部信息，宽高
options.inJustDecodeBounds = true;
//得到图片的真实宽高
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;

//得到屏幕的宽高
WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
int screenHeight = wm.getDefaultDisplay().getHeight();
int screenWidth = wm.getDefaultDisplay().getWidth();

//得到缩放比例
int scale = 1;
int scaleX = imageWidth / screenWidth;
int scaleY = imageHeight / screenHeight;
if (scaleX > scaleY & scaleX >=1) {//表示如果宽的缩放比例大于高的，并且scaleX>=1都为true
scale = scaleX;
}
if (scaleY > scaleX & scaleY >=1) {//表示如果高的缩放比例大于宽的，并且scaleY>=1都为true
scale = scaleY;
}
//解析图片
options.inJustDecodeBounds = false;
//修改图片的缩放比例，如果scale=4说明图片缩小4倍，像数=1/16
options.inSampleSize = scale;

Bitmap bm = BitmapFactory.decodeFile("/sdcard/images/1.jpg", options);
mImageView.setImageBitmap(bm);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ImageView
android:id="@+id/imageView"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" />

<EditText
android:id="@+id/editText1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10" >

<requestFocus />
</EditText>

<Button
android:id="@+id/btnLoadImage"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="loadImage"
android:text="加载图片" />

</LinearLayout>