Android加载大图片到内存

在android中要加载一张大图片到内存中如果通过如下方式进行

    Bitmap bitmap= BitmapFactory.decodeFile("/sdcard/a.jpg");         iv.setImageBitmap(bitmap);  

则会抛出内存溢出异常Caused by: java.lang.OutOfMemoryError

正确的做法应该是这样的：

    public class MainActivity extends Activity {            private ImageView iv;            private int windowHeight;            private int windowWidth;                    @Override            protected void onCreate(Bundle savedInstanceState) {                super.onCreate(savedInstanceState);                setContentView(R.layout.activity_main);                iv = (ImageView) findViewById(R.id.iv);                WindowManager win = (WindowManager) getSystemService(WINDOW_SERVICE);                windowHeight = win.getDefaultDisplay().getHeight();                windowWidth = win.getDefaultDisplay().getWidth();            }                    @Override            public boolean onCreateOptionsMenu(Menu menu) {                // Inflate the menu; this adds items to the action bar if it is present.                getMenuInflater().inflate(R.menu.main, menu);                return true;            }                    public void load(View view) {                            /*   Bitmap bitmap= BitmapFactory.decodeFile("/sdcard/a.jpg");                iv.setImageBitmap(bitmap);*/                                 // 图片解析的配置                BitmapFactory.Options options = new 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;                BitmapFactory.decodeFile("/sdcard/a.jpg", options);                int imageHeight = options.outHeight;                int imageWidth = options.outWidth;                // 计算缩放比例                int scaleX = imageWidth / windowWidth;                int scaleY = imageHeight / windowHeight;                int scale = 1;                if (scaleX > scaleY & scaleY >= 1) {                    scale = scaleX;                        }else if (scaleY > scaleX & scaleX >= 1) {                    scale = scaleY;                        }                //真的解析图片                options.inJustDecodeBounds=false;                //设置采样率                options.inSampleSize=scale;                Bitmap bitmap=BitmapFactory.decodeFile("/sdcard/a.jpg", options);                iv.setImageBitmap(bitmap);            }                }  

xml文件

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"            xmlns:tools="http://schemas.android.com/tools"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:orientation="vertical"            tools:context=".MainActivity" >                    <Button                android:onClick="load"                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:text="加载大图片到内存" />                    <ImageView                android:id="@+id/iv"                android:layout_width="match_parent"                android:layout_height="match_parent" />                </LinearLayout>  

在这种情况下，是将大分辨率的图片按照一定的比例缩小然后加载进内存，就不会出现内存溢出的现象了。