加载大图片到内存

public class MainActivity extends Activity {

	private ImageView iv;
	private int width;
	private int height;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		iv = (ImageView)findViewById(R.id.iv);
		
		//得到手机屏幕的宽高
		WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
		width = wm.getDefaultDisplay().getWidth();
		height = wm.getDefaultDisplay().getHeight();
		
		//Call requires API level 13 (current min is 8)
		//Point outSize = new Point();
		//wm.getDefaultDisplay().getSize(outSize);//
		//int width = outSize.x;
		//int height = outSize.y;
	}

	public void click(View view){
		//图片加载后大小小于堆内存（16M）用此方法可显示
		//Bitmap bm = BitmapFactory.decodeFile("/sdcard/d.jpg");
		//iv.setImageBitmap(bm);
		
		//图片解析的配置
		BitmapFactory.Options opts = new Options();
		//不去真的解析图片，只是获取图片的头部信息，宽高。
		opts.inJustDecodeBounds = true;
		BitmapFactory.decodeFile("/sdcard/d.jpg", opts);
		
		int imageWidth = opts.outWidth;
		int imageHeight = opts.outHeight;
		
		
		//计算缩放比例
		int scaleX = imageWidth/width;
		int scaleY = imageHeight/height;
		int scale = 1;
		if(scaleX>scaleY && scaleY>=1){
			scale = scaleX;
		}
		if(scaleY>scaleX && scaleX>=1){
			scale = scaleY;
		}
		//真的解析图片
		opts.inJustDecodeBounds = false;
		//采样率
		opts.inSampleSize = scale;
		Bitmap bm = BitmapFactory.decodeFile("/sdcard/d.jpg", opts);
		iv.setImageBitmap(bm);
		
	}
}