Utils.java

package com.hotpatch;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.Signature;
import android.os.Build;
import android.text.TextUtils;
import android.util.DisplayMetrics;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Iterator;
import java.util.List;


public class Utils {

    /**
     * Get the Signature of apk file which is not installed.
     *
     * @param apkPath
     * @return
     */
    public static String getApkSignature(String apkPath) {
        String PATH_PackageParser = "android.content.pm.PackageParser";
        try {
            Class<?> pkgParserCls = Class.forName(PATH_PackageParser);
            Class<?>[] typeArgs = new Class[1];
            typeArgs[0] = String.class;
            Object[] valueArgs = new Object[1];
            valueArgs[0] = apkPath;
            Object pkgParser;
            if (Build.VERSION.SDK_INT > 19) {
                pkgParser = pkgParserCls.newInstance();
            } else {
                Constructor constructor = pkgParserCls.getConstructor(typeArgs);
                pkgParser = constructor.newInstance(valueArgs);
            }

            DisplayMetrics metrics = new DisplayMetrics();
            metrics.setToDefaults();

            Object pkgParserPkg = null;
            if (Build.VERSION.SDK_INT > 19) {
                typeArgs = new Class[2];
                typeArgs[0] = File.class;
                typeArgs[1] = int.class;

                Method pkgParser_parsePackageMtd = pkgParserCls.getDeclaredMethod(
                        "parsePackage", typeArgs);
                pkgParser_parsePackageMtd.setAccessible(true);

                valueArgs = new Object[2];
                valueArgs[0] = new File(apkPath);
                valueArgs[1] = PackageManager.GET_SIGNATURES;
                pkgParserPkg = pkgParser_parsePackageMtd.invoke(pkgParser,
                        valueArgs);
            } else {
                typeArgs = new Class[4];
                typeArgs[0] = File.class;
                typeArgs[1] = String.class;
                typeArgs[2] = DisplayMetrics.class;
                typeArgs[3] = int.class;

                Method pkgParser_parsePackageMtd = pkgParserCls.getDeclaredMethod(
                        "parsePackage", typeArgs);
                pkgParser_parsePackageMtd.setAccessible(true);

                valueArgs = new Object[4];
                valueArgs[0] = new File(apkPath);
                valueArgs[1] = apkPath;
                valueArgs[2] = metrics;
                valueArgs[3] = PackageManager.GET_SIGNATURES;
                pkgParserPkg = pkgParser_parsePackageMtd.invoke(pkgParser,
                        valueArgs);
            }


            typeArgs = new Class[2];
            typeArgs[0] = pkgParserPkg.getClass();
            typeArgs[1] = int.class;
            Method pkgParser_collectCertificatesMtd = pkgParserCls.getDeclaredMethod("collectCertificates", typeArgs);
            valueArgs = new Object[2];
            valueArgs[0] = pkgParserPkg;
            valueArgs[1] = PackageManager.GET_SIGNATURES;
            pkgParser_collectCertificatesMtd.invoke(pkgParser, valueArgs);
            Field packageInfoFld = pkgParserPkg.getClass().getDeclaredField(
                    "mSignatures");
            Signature[] info = (Signature[]) packageInfoFld.get(pkgParserPkg);
            return info[0].toCharsString();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * Get the Signature of the apk file which package name is @param packageName
     *
     * @param context
     * @param packageName
     * @return packageSignatrue
     */
    public static String getInstallPackageSignature(Context context,
                                                    String packageName) {
        PackageManager pm = context.getPackageManager();
        List<PackageInfo> apps = pm
                .getInstalledPackages(PackageManager.GET_SIGNATURES);

        Iterator<PackageInfo> iter = apps.iterator();
        while (iter.hasNext()) {
            PackageInfo packageinfo = iter.next();
            String thisName = packageinfo.packageName;
            if (thisName.equals(packageName)) {
                return packageinfo.signatures[0].toCharsString();
            }
        }

        return null;
    }

    public static String getMd5ByFile(File file) {
        String value = null;
        FileInputStream in=null;
        try {
            in = new FileInputStream(file);
            MappedByteBuffer byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length());
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(byteBuffer);
            BigInteger bi = new BigInteger(1, md5.digest());
            value = bi.toString(16);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (null != in) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return value;
    }

    public static String md5(String string) {
        byte[] hash;
        try {
            hash = MessageDigest.getInstance("MD5").digest(string.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("Huh, MD5 should be supported?", e);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("Huh, UTF-8 should be supported?", e);
        }

        StringBuilder hex = new StringBuilder(hash.length * 2);
        for (byte b : hash) {
            if ((b & 0xFF) < 0x10) hex.append("0");
            hex.append(Integer.toHexString(b & 0xFF));
        }
        return hex.toString();
    }

    public static String getCacheApkFilePath(Context ctx,String fileUrl){
        return ctx.getExternalCacheDir()+"/"+md5(fileUrl)+".apk";
    }

    /**
     *
     * Compare  the patch apk to the apk which package name is ctx.getPackageName()
     * @param  ctx
     * @param  apkFile the patch apk
     * @return the result of compare
     * **/
    public static boolean isSignEqual(Context ctx,String apkFile){
        String packageSign=getInstallPackageSignature(ctx,ctx.getPackageName());
        String apkFileSign=getApkSignature(apkFile);
        return TextUtils.equals(packageSign,apkFileSign);
    }

    public static String getVersionName(Context context) {
        try {
            PackageManager packageManager = context.getPackageManager();
            PackageInfo packInfo = packageManager.getPackageInfo(context.getPackageName(), 0);
            String version =String.valueOf(packInfo.versionName);
            return version;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}