我找到了 2 个解决方案(从这里和其他答案中找到):
object MD5Util {
private val messageDigest: MessageDigest?
init {
val testMd =
try {
MessageDigest.getInstance("MD5")
} catch (e: Exception) {
null
}
messageDigest = testMd
}
private fun hex(array: ByteArray): String {
val sb = StringBuilder()
for (b in array)
sb.append(Integer.toHexString((b.toInt() and 0xFF) or 0x100).substring(1, 3))
return sb.toString()
}
@JvmStatic
fun md5Hex(message: String): String {
if (messageDigest != null)
try {
return hex(messageDigest.digest(message.toByteArray(charset("CP1252"))))
} catch (e: Exception) {
throw e
}
throw Exception("messageDigest not found")
}
@JvmStatic
fun md5(s: String): String {
if (messageDigest != null)
try {
val hash: ByteArray = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT)
messageDigest.digest(s.toByteArray(StandardCharsets.UTF_8))
else
messageDigest.digest(s.toByteArray(charset("UTF-8")))
val sb = StringBuilder()
for (aHash in hash) {
val hex = Integer.toHexString(aHash.toInt())
if (hex.length == 1)
sb.append('0').append(hex[hex.length - 1])
else
sb.append(hex.substring(hex.length - 2))
}
return sb.toString()
} catch (e: Exception) {
throw e
}
throw Exception("messageDigest not found")
}
}
根据一些基准,我可以说该md5
函数比该md5Hex
函数快两倍左右。这是测试:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
AsyncTask.execute {
val emailList=ArrayList<String>()
for (i in 0 until 100000)
emailList.add( generateRandomEmail(10))
var startTime = System.currentTimeMillis()
for (email in emailList)
MD5Util.md5(email)
var endTime = System.currentTimeMillis()
Log.d("AppLog", "md5 - time taken: ${endTime - startTime}")
startTime = System.currentTimeMillis()
for (email in emailList)
MD5Util.md5Hex(email)
endTime = System.currentTimeMillis()
Log.d("AppLog", "md5Hex - time taken: ${endTime - startTime}")
}
}
companion object {
private const val ALLOWED_CHARS = "abcdefghijklmnopqrstuvwxyz" + "1234567890" + "_-."
@Suppress("SpellCheckingInspection")
fun generateRandomEmail(@IntRange(from = 1) localEmailLength: Int, host: String = "gmail.com"): String {
val firstLetter = RandomStringUtils.random(1, 'a'.toInt(), 'z'.toInt(), false, false)
val temp = if (localEmailLength == 1) "" else RandomStringUtils.random(localEmailLength - 1, ALLOWED_CHARS)
return "$firstLetter$temp@$host"
}
}
}
gradle 文件有这个:
implementation 'org.apache.commons:commons-lang3:3.7'