Android 檔案SHA-MD5校驗工具類

import android.util.Log;

import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 加密工具類
 * author：wiki on 2018/12/12
 * email：[email protected]
 */
public class SHAUtil {

public static final String TAG = SHAUtil.class.getSimpleName();

/**
* 傳入文字內容，返回 SHA-256 串
*
* @param strText
* @return
*/
public static String getTextSHA256(final String strText) {
return SHA(strText, "SHA-256");
}

/**
* 傳入文字內容，返回 SHA-512 串
*
* @param strText
* @return
*/
public static String getTextSHA512(final String strText) {
return SHA(strText, "SHA-512");
}

/**
* 字串 SHA 加密
*
* @param strText
* @return
*/
private static String SHA(final String strText, final String strType) {
// 返回值
String strResult = null;

// 是否是有效字串
if (strText != null && strText.length() > 0) {
try {
// SHA 加密開始
// 建立加密物件 並傳入加密型別
MessageDigest messageDigest = MessageDigest.getInstance(strType);
// 傳入要加密的字串
messageDigest.update(strText.getBytes());
// 得到 byte 型別結果
byte byteBuffer[] = messageDigest.digest();

// 將 byte 轉換為 string
StringBuffer strHexString = new StringBuffer();
// 遍歷 byte buffer
for (int i = 0; i < byteBuffer.length; i++) {
String hex = Integer.toHexString(0xff & byteBuffer[i]);
if (hex.length() == 1) {
strHexString.append('0');
}
strHexString.append(hex);
}
// 得到返回結果
strResult = strHexString.toString();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}

return strResult;
}


/**
* 校驗
* @param filename 檔名
* @param strType校驗型別--SHA-1,SHA-256,SHA-384,SHA-512,MD5,MD2
* @returnbyte[]
* @throws Exception
*/
private static byte[] createChecksum(String filename, String strType) throws Exception {
InputStream fis = new FileInputStream(filename);//將流型別字串轉換為String型別字串

byte[] buffer = new byte[1024];
MessageDigest complete = MessageDigest.getInstance(strType);
int numRead;

do {
numRead = fis.read(buffer);//從檔案讀到buffer，最多裝滿buffer
if (numRead > 0) {
complete.update(buffer, 0, numRead);//用讀到的位元組進行strType的計算，第二個引數是偏移量
}
} while (numRead != -1);

fis.close();
return complete.digest();
}


public static String getMD5Checksum(String filename) throws Exception {
byte[] b = createChecksum(filename, "MD5");
return byte2String(b);
}

public static String getSHA256Checksum(String filename) throws Exception {
byte[] b = createChecksum(filename, "SHA-256");
return byte2String(b);
}

public static String getSHA512Checksum(String filename) throws Exception {
byte[] b = createChecksum(filename, "SHA-512");
return byte2String(b);
}

private static String byte2String(byte[] bytes) {
StringBuilder result = new StringBuilder();

for (byte b : bytes) {
//加0x100是因為有的b[i]的十六進位制只有1位
result.append(Integer.toString((b & 0xff) + 0x100, 16).substring(1));
}
Log.i(TAG, "checkSum: " + result.toString());
return result.toString();
}

}