比较文件MD5

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package com.xl.frame.util;import android.text.TextUtils;import android.util.Log;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.math.BigInteger;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;public class MD5 {    private static final String TAG = "MD5";    public static boolean checkMD5(String md5, File updateFile) {        if (TextUtils.isEmpty(md5) || updateFile == null) {            Log.e(TAG, "MD5 string empty or updateFile null");            return false;        }        String calculatedDigest = null;  try {   calculatedDigest = calculateMD5(updateFile);  } catch (Exception e) {   e.printStackTrace();  }          if (calculatedDigest == null) {            Log.e(TAG, "calculatedDigest null");            return false;        }        Log.v(TAG, "Calculated digest: " + calculatedDigest);        Log.v(TAG, "Provided digest: " + md5);        return calculatedDigest.equalsIgnoreCase(md5);    }    public static String calculateMD5(File updateFile) {        MessageDigest digest;        try {            digest = MessageDigest.getInstance("MD5");        } catch (NoSuchAlgorithmException e) {            Log.e(TAG, "Exception while getting digest", e);            return null;        }        InputStream is;        try {            is = new FileInputStream(updateFile);        } catch (FileNotFoundException e) {            Log.e(TAG, "Exception while getting FileInputStream", e);            return null;        }        byte[] buffer = new byte[8192];        int read;        try {            while ((read = is.read(buffer)) > 0) {                digest.update(buffer, 0, read);            }            byte[] md5sum = digest.digest();            BigInteger bigInt = new BigInteger(1, md5sum);            String output = bigInt.toString(16);            // Fill to 32 chars            output = String.format("%32s", output).replace(' ', '0');            return output;        } catch (IOException e) {            throw new RuntimeException("Unable to process file for MD5", e);        } finally {            try {                is.close();            } catch (IOException e) {                Log.e(TAG, "Exception on closing MD5 input stream", e);            }        }    }}
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