checksum md5加密解密 - 如何在Android中為文件生成MD5校驗和?




java sha256 (8)

在我的應用程序中,我需要為文件生成MD5校驗和。 你能告訴我是否有辦法實現這一目標?

謝謝。


Answers

public static String getMd5OfFile(String filePath)
{
    String returnVal = "";
    try 
    {
        InputStream   input   = new FileInputStream(filePath); 
        byte[]        buffer  = new byte[1024];
        MessageDigest md5Hash = MessageDigest.getInstance("MD5");
        int           numRead = 0;
        while (numRead != -1)
        {
            numRead = input.read(buffer);
            if (numRead > 0)
            {
                md5Hash.update(buffer, 0, numRead);
            }
        }
        input.close();

        byte [] md5Bytes = md5Hash.digest();
        for (int i=0; i < md5Bytes.length; i++)
        {
            returnVal += Integer.toString( ( md5Bytes[i] & 0xff ) + 0x100, 16).substring( 1 );
        }
    } 
    catch(Throwable t) {t.printStackTrace();}
    return returnVal.toUpperCase();
}

這個方法適用於我,131MB的zip文件。 MD5計算匹配由AccuHash( http://www.accuhash.com )在同一文件上計算的匹配

public static String calculateMD5(File updateFile) {
        MessageDigest digest;
        try {
            digest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            Log.e("calculateMD5", "Exception while getting Digest", e);
            return null;
        }

        InputStream is;
        try {
            is = new FileInputStream(updateFile);
        } catch (FileNotFoundException e) {
            Log.e("calculateMD5", "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("calculateMD5", "Exception on closing MD5 input stream", e);
            }
        }
    }   

此代碼來自CMupdater,來自CyanogenMod 10.2 android ROM。 它將下載的ROM測試到更新程序App中。

代碼: https://github.com/CyanogenMod/android_packages_apps_CMUpdater/blob/cm-10.2/src/com/cyanogenmod/updater/utils/MD5.javahttps://github.com/CyanogenMod/android_packages_apps_CMUpdater/blob/cm-10.2/src/com/cyanogenmod/updater/utils/MD5.java

它就像一個魅力:

/*
 * Copyright (C) 2012 The CyanogenMod Project
 *
 * * Licensed under the GNU GPLv2 license
 *
 * The text of the license can be found in the LICENSE file
 * or at https://www.gnu.org/licenses/gpl-2.0.txt
 */

package com.cyanogenmod.updater.utils;

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 = calculateMD5(updateFile);
        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);
            }
        }
    }
}

將文件內容轉換為字符串並使用以下方法:

public static String getMD5EncryptedString(String encTarget){
        MessageDigest mdEnc = null;
        try {
            mdEnc = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            System.out.println("Exception while encrypting to md5");
            e.printStackTrace();
        } // Encryption algorithm
        mdEnc.update(encTarget.getBytes(), 0, encTarget.length());
        String md5 = new BigInteger(1, mdEnc.digest()).toString(16);
        while ( md5.length() < 32 ) {
            md5 = "0"+md5;
        }
        return md5;
    }

請注意,這種簡單的方法適用於較小的字符串,但對大文件效率不高。 對於後者,請參閱dentex的答案 。


如果您需要計算大文件的MD5 ,您可能想要使用它:

進口:

import java.security.MessageDigest;

方法:

 private byte[] calculateMD5ofFile(String location) throws IOException, NoSuchAlgorithmException {
        FileInputStream fs= new FileInputStream(location);
        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] buffer=new byte[bufferSize];
        int bytes=0;
        do{
            bytes=fs.read(buffer,0,bufferSize);
            if(bytes>0)
                md.update(buffer,0,bytes);

        }while(bytes>0);
        byte[] Md5Sum = md.digest();
        return Md5Sum;
    }

參考: https://docs.oracle.com/javase/7/docs/api/java/security/MessageDigest.htmlhttps://docs.oracle.com/javase/7/docs/api/java/security/MessageDigest.html

將字節數組轉換為十六進制。 用這個

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

參考在Java中,如何將字節數組轉換為十六進制數字字符串,同時保持前導零?


我有相同的任務,這個代碼非常好:

public static String fileToMD5(String filePath) {
    InputStream inputStream = null;
    try {
        inputStream = new FileInputStream(filePath);
        byte[] buffer = new byte[1024];
        MessageDigest digest = MessageDigest.getInstance("MD5");
        int numRead = 0;
        while (numRead != -1) {
            numRead = inputStream.read(buffer);
            if (numRead > 0)
                digest.update(buffer, 0, numRead);
        }
        byte [] md5Bytes = digest.digest();
        return convertHashToString(md5Bytes);
    } catch (Exception e) {
        return null;
    } finally {
        if (inputStream != null) {
            try {
                inputStream.close();
            } catch (Exception e) { }
        }
    }
}

private static String convertHashToString(byte[] md5Bytes) {
    String returnVal = "";
    for (int i = 0; i < md5Bytes.length; i++) {
        returnVal += Integer.toString(( md5Bytes[i] & 0xff ) + 0x100, 16).substring(1);
    }
    return returnVal.toUpperCase();
}

我發現以下內容非常好用:

Process process = Runtime.getRuntime().exec("md5 "+fileLocation);
BufferedReader inputStream = new BufferedReader(new InputStreamReader(process.getInputStream()));
String result = inputStream.readLine().split(" ")[0];

這會調用內置的md5命令。 變量fileLocation將設置為文件的位置。 當然我建議在這附近構建一些檢查來檢查文件是否存在。


這是我如何做到的:

using System.IO;
using System.Security.Cryptography;

public string checkMD5(string filename)
{
    using (var md5 = MD5.Create())
    {
        using (var stream = File.OpenRead(filename))
        {
            return Encoding.Default.GetString(md5.ComputeHash(stream));
        }
    }
}






android md5 checksum