android客户端加载网络大图片如何避免内存溢出

 1         Options opts = new Options();
 2         opts.inJustDecodeBounds = true; //设置为true, 加载器不会返回图片, 而是设置Options对象中以out开头的字段.即仅仅解码边缘区域
 3         BitmapFactory.decodeFile(filePath, opts);
 4         
 5         // 得到图片的宽和高
 6         int imageWidth = opts.outWidth;
 7         int imageHeight = opts.outHeight;
 8         
 9         // 获取屏幕的宽和高
10         Display display = this.getWindowManager().getDefaultDisplay(); // 获取默认窗体显示的对象
11         int screenWidth = display.getWidth();
12         int screenHeight = display.getHeight();
13         
14         // 计算缩放比例
15         int widthScale = imageWidth / screenWidth;
16         int heightScale = imageHeight / screenHeight;
17         
18         int scale = widthScale > heightScale ? widthScale:heightScale;20         
21          // 指定加载可以加载出图片.
22         opts.inJustDecodeBounds = false;
23         // 使用计算出来的比例进行缩放
24         opts.inSampleSize = scale;
25         Bitmap bm = BitmapFactory.decodeFile(path, opts);

    /**
     * 计算图片的缩放比例
     * @return
     */
    public int getScare() {
        try {
            HttpClient client = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(imageUrl);
            HttpResponse response = client.execute(httpGet);
            int code = response.getStatusLine().getStatusCode();

            if (200 == code) {
                InputStream is = response.getEntity().getContent();
                Options opts = new Options();
                opts.inJustDecodeBounds = true;
                BitmapFactory.decodeStream(is, null, opts);

                int imageWidth = opts.outWidth;
                int imageHeight = opts.outHeight;

                Display display = ImageActivity.this.getWindowManager()
                        .getDefaultDisplay();
                int screenWidth = display.getWidth();
                int screenHeight = display.getHeight();

                int widthscale = imageWidth / screenWidth;
                int heightscale = imageHeight / screenHeight;
                int scale = widthscale > heightscale ? widthscale : heightscale;

                return scale;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return 1;//网络连接失败时默认返回1
    }

/**
     * 获取网络图片
     */
    protected void getNetImage() {
        try {
            HttpClient client = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(imageUrl);
            HttpResponse response = client.execute(httpGet);
            int code = response.getStatusLine().getStatusCode();

            if (200 == code) {
                InputStream is = response.getEntity().getContent();

                Options opts = new Options();
                
                //根据计算出的比例进行缩放
                int scale = getScare();
                opts.inSampleSize = scale;
                 
                Bitmap bm = BitmapFactory.decodeStream(is, null, opts);

                //将bm发生给主线程用于显示图片，更新UI
                Message msg = Message.obtain();
                msg.obj = bm;
                handler.sendMessage(msg);

            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

//显示图片
    Handler handler = new Handler() {
        public void handleMessage(Message msg) {
            Bitmap bm = (Bitmap) msg.obj;
            iv.setImageBitmap(bm);
        };
    };