常用方法Util集合

1、计算listview高度，以解决listview与其他滚动冲突问题

public static void setListViewHeightBasedOnChildren(ListView listView) {
       ListAdapter listAdapter = listView.getAdapter();
       if (listAdapter == null) {
           return;
       }

       int totalHeight = 0;
       for (int i = 0; i < listAdapter.getCount(); i++) {
           View listItem = listAdapter.getView(i, null, listView);
           listItem.measure(0, 0);
           totalHeight += listItem.getMeasuredHeight();
       }

       ViewGroup.LayoutParams params = listView.getLayoutParams();
       params.height = totalHeight + (listView.getDividerHeight() * (listAdapter.getCount() - 1));
       listView.setLayoutParams(params);
   }

2、获取app的签名值，以方便第三方的调试发布。通过代码获取值

public static String getSHA1(Context context) {
    try {
        PackageInfo info = context.getPackageManager().getPackageInfo(
                context.getPackageName(), PackageManager.GET_SIGNATURES);

        byte[] cert = info.signatures[0].toByteArray();

        MessageDigest md = MessageDigest.getInstance("SHA1");
        byte[] publicKey = md.digest(cert);
        StringBuffer hexString = new StringBuffer();
        for (int i = 0; i < publicKey.length; i++) {
            String appendString = Integer.toHexString(0xFF & publicKey[i])
                    .toUpperCase(Locale.US);
            if (appendString.length() == 1)
                hexString.append("0");
            hexString.append(appendString);
            hexString.append(":");
        }
        return hexString.toString();
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return null;
} 

public static String getMD5(Context context) {
    String fingerprint = "error!";
    try {
        PackageInfo info = context.getPackageManager().getPackageInfo(
                context.getPackageName(), PackageManager.GET_SIGNATURES);
        byte[] cert = info.signatures[0].toByteArray();
        MessageDigest digest = MessageDigest.getInstance("MD5");
        if (digest != null) {
            byte[] digestBytes = digest.digest(cert);
            StringBuilder sb = new StringBuilder();
            for (byte digestByte : digestBytes) {
                sb.append((Integer.toHexString((digestByte & 0xFF) | 0x100)).substring(1, 3));
            }
            fingerprint = sb.toString();
        }
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return fingerprint;
}

public static String getSHA256(Context context) {
    String fingerprint = "error!";
    try {
        PackageInfo info = context.getPackageManager().getPackageInfo(
                context.getPackageName(), PackageManager.GET_SIGNATURES);
        byte[] cert = info.signatures[0].toByteArray();
        MessageDigest digest = MessageDigest.getInstance("SHA256");
        if (digest != null) {
            byte[] digestBytes = digest.digest(cert);
            StringBuilder sb = new StringBuilder();
            for (byte digestByte : digestBytes) {
                sb.append((Integer.toHexString((digestByte & 0xFF) | 0x100)).substring(1, 3));
            }
            fingerprint = sb.toString();
        }
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return fingerprint;
}

3、获取圆形图片，这样不需要特意写一个圆形图片控件了。

/**
 * 获取裁剪后的圆形图片
 *
 * @ param radius半径
 */
public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {
    Bitmap scaledSrcBmp;
    int diameter = radius * 2;
    // 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片
    int bmpWidth = bmp.getWidth();
    int bmpHeight = bmp.getHeight();
    int squareWidth = 0, squareHeight = 0;
    int x = 0, y = 0;
    Bitmap squareBitmap;
    if (bmpHeight > bmpWidth) {// 高大于宽
        squareWidth = squareHeight = bmpWidth;
        x = 0;
        y = (bmpHeight - bmpWidth) / 2;
        // 截取正方形图片
        squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
    } else if (bmpHeight < bmpWidth) {// 宽大于高
        squareWidth = squareHeight = bmpHeight;
        x = (bmpWidth - bmpHeight) / 2;
        y = 0;
        squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
    } else {
        squareBitmap = bmp;
    }
    if (squareBitmap.getWidth() != diameter || squareBitmap.getHeight() != diameter) {
        scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter, diameter, true);
    } else {
        scaledSrcBmp = squareBitmap;
    }
    Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(),
            scaledSrcBmp.getHeight(),
            Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    Paint paint = new Paint();
    Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight());

    paint.setAntiAlias(true);
    paint.setFilterBitmap(true);
    paint.setDither(true);
    canvas.drawARGB(0, 0, 0, 0);
    canvas.drawCircle(scaledSrcBmp.getWidth() / 2,
            scaledSrcBmp.getHeight() / 2,
            scaledSrcBmp.getWidth() / 2,
            paint);
    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);
    bmp = null;
    squareBitmap = null;
    scaledSrcBmp = null;
    return output;
}

4、Toast单例

public class ToastUtil {


    private static String oldMsg;
    protected static Toast toast   = null;
    private static long oneTime=0;
    private static long twoTime=0;


    public static void showToastShort(Context context, String message){
        if(toast==null){
            toast =Toast.makeText(context, message, Toast.LENGTH_SHORT);
            toast.show();
            oneTime=System.currentTimeMillis();
        }else{
            twoTime=System.currentTimeMillis();
            if(message.equals(oldMsg)){
                if(twoTime-oneTime>Toast.LENGTH_SHORT){
                    toast.show();
                }
            }else{
                oldMsg = message;
                toast.setText(message);
                toast.show();
            }
        }
        oneTime=twoTime;
    }
}