[移动开发]android请求获取图片的方法

public static Bitmap getUrlBitmap(String path) {
    Bitmap bm = null;
    try {
        URL url = new URL(path);//创建一个URL对象，其参数为网络图片的链接地址
        //使用一个URL对象开启一个链接
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        //设置相关参数
        con.setDoInput(true);
        con.setUseCaches(true);  //不允许使用缓存
        con.setConnectTimeout(5000);//设置超时
        con.setReadTimeout(10000);
        con.connect();
        int code = con.getResponseCode();
        if (code==200) {
            InputStream is = con.getInputStream();//获取输入流
            bm = getFitSampleBitmap(is);//将输入流解码为Bitmap对象
            is.close();
        }
        con.disconnect();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return bm;
}

/***
 * 读取获得Bitmap对象
 * @param inputStream
 * @return
 * @throws Exception
 */
public  static  Bitmap  getFitSampleBitmap(InputStream  inputStream) throws Exception{
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;//设置该项可以获得图片原始宽高度
    byte[] bytes = readStream(inputStream);
    BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);
    options.inSampleSize=computeSampleSize(options, -1, 128*128);
    
    options.inJustDecodeBounds=false;
    return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);
}

/**
 * 从inputStream中获取字节流 数组大小
 **/
public static byte[] readStream(InputStream inStream) throws Exception{
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int len = 0;
    while ((len = inStream.read(buffer)) != -1) {
        outStream.write(buffer, 0, len);
    }
    outStream.close();
    inStream.close();
    return outStream.toByteArray();
}

/***
 * 计算图片大小
 * @param options
 * @param minSideLength
 * @param maxNumOfPixels
 * @return
 */
public static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
    int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels);
    int roundedSize;
    if (initialSize <= 8) {
        roundedSize = 1;
        while (roundedSize < initialSize) {
            roundedSize <<= 1;
        }
    } else {
        roundedSize = (initialSize + 7) / 8 * 8;
    }
    return roundedSize;
}

/***
 * 计算获得图片大小
 * @param options
 * @param minSideLength
 * @param maxNumOfPixels
 * @return
 */
private static int computeInitialSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {
    double w = options.outWidth;
    double h = options.outHeight;
    int lowerBound = (maxNumOfPixels == -1) ?
            1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));

    int upperBound = (minSideLength == -1) ?
            128 :(int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength));

    if (upperBound < lowerBound) {
        // return the larger one when there is no overlapping zone.
        return lowerBound;
    }
    if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
        return 1;
    } else if (minSideLength == -1) {
        return lowerBound;
    } else {
        return upperBound;
    }
}