Utils.java

package com.jerey.lruCache;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.PixelFormat;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;

import java.io.ByteArrayOutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Utils {
    public static int getAppVersion(Context context) {
        try {
            PackageInfo info = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
            return info.versionCode;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        return 1;
    }


    public static String hashKeyForDisk(String key) {
        String cacheKey;
        try {
            final MessageDigest mDigest = MessageDigest.getInstance("MD5");
            mDigest.update(key.getBytes());
            cacheKey = bytesToHexString(mDigest.digest());
        } catch (NoSuchAlgorithmException e) {
            cacheKey = String.valueOf(key.hashCode());
        }
        return cacheKey;
    }

    public static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0xFF & bytes[i]);
            if (hex.length() == 1) {
                sb.append('0');
            }
            sb.append(hex);
        }
        return sb.toString();
    }

    public static byte[] bitmap2Bytes(Bitmap bm) {
        if (bm == null) {
            return null;
        }
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();
    }

    public static Bitmap bytes2Bitmap(byte[] bytes) {
        return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
    }


    /**
     * Drawable → Bitmap
     */
    public static Bitmap drawable2Bitmap(Drawable drawable) {
        if (drawable == null) {
            return null;
        }
        // 取 drawable 的长宽
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        // 取 drawable 的颜色格式
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;
        // 建立对应 bitmap
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        // 建立对应 bitmap 的画布
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        // 把 drawable 内容画到画布中
        drawable.draw(canvas);
        return bitmap;
    }

    /*
         * Bitmap → Drawable
		 */
    @SuppressWarnings("deprecation")
    public static Drawable bitmap2Drawable(Bitmap bm) {
        if (bm == null) {
            return null;
        }
        BitmapDrawable bd = new BitmapDrawable(bm);
        bd.setTargetDensity(bm.getDensity());
        return new BitmapDrawable(bm);
    }
}