android（38）（加载大图到内存）

1.加载大图进内存：public class MainActivity extends Activity {    private ImageView iv;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        iv = (ImageView) findViewById(R.id.iv);    }    public void click(View view){        //相当消耗内存资源 根据图片的分辨率而定        // Bitmap bitmap = BitmapFactory.decodeFile("/mnt/sdcard/photo.jpg");        // iv.setImageBitmap(bitmap);        //1.得到屏幕的宽高信息        WindowManager wm = getWindowManager();        int screenWidth = wm.getDefaultDisplay().getWidth();        int screenHeight = wm.getDefaultDisplay().getHeight();        System.out.println("屏幕宽高："+screenWidth+"-"+screenHeight);        //2.得到图片的宽高。        BitmapFactory.Options opts = new Options();//解析位图的附加条件        opts.inJustDecodeBounds = true;//不去解析真实的位图，只是获取这个位图的头文件信息        Bitmap bitmap = BitmapFactory.decodeFile("/mnt/sdcard/photo.jpg", opts);        int bitmapWidth = opts.outWidth;        int bitmapHeight = opts.outHeight;        System.out.println("图片宽高： "+bitmapWidth+"-"+bitmapHeight);        //3.计算缩放比例        int dx = bitmapWidth/screenWidth;        int dy = bitmapHeight/screenHeight;        int scale = 1;        if(dx>dy&&dy>1){            System.out.println("按照水平方法缩放,缩放比例："+dx);             scale = dx;        }        if(dy>dx&&dx>1){            System.out.println("按照垂直方法缩放,缩放比例："+dy);            scale = dy;        }        //4.缩放加载图片到内存。        opts.inSampleSize = scale;        opts.inJustDecodeBounds = false;//真正的去解析这个位图。        bitmap = BitmapFactory.decodeFile("/mnt/sdcard/photo.jpg", opts);        iv.setImageBitmap(bitmap);    }}