Android学习笔记----Java字符串MD5加密

/**
* MD5单向加密，32位，用于加密密码，因为明文密码在信道中传输不安全，明文保存在本地也不安全
*
* @param str
* @return
*/
public static String md5(String str) {
MessageDigest md5 = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
e.printStackTrace();
return "";
}

char[] charArray = str.toCharArray();
byte[] byteArray = new byte[charArray.length];

for (int i = 0; i < charArray.length; i++) {
byteArray[i] = (byte) charArray[i];
}
byte[] md5Bytes = md5.digest(byteArray);

StringBuffer hexValue = new StringBuffer();
for (int i = 0; i < md5Bytes.length; i++) {
int val = ((int) md5Bytes[i]) & 0xff;
if (val < 16) {
hexValue.append("0");
}
hexValue.append(Integer.toHexString(val));
}
return hexValue.toString();
}