SHA安全加密标准，是至今世界上使用最广泛且安全的压缩算法之一，随着密码学研究的不断深入和计算机技术的快速发展，SHA-256算法得到全面推广应用。
java代码实现：
package com.caojiulu;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class Main {
public static void main(String[] args) {
}
public static String getSHA256StrJava(String str) {
MessageDigest messageDigest;
String encodeStr = "";
try {
messageDigest = MessageDigest.getInstance("SHA-256");
messageDigest.update(str.getBytes("UTF-8"));
encodeStr = byte2Hex(messageDigest.digest());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return encodeStr;
}
private static String byte2Hex(byte[] bytes) {
StringBuffer stringBuffer = new StringBuffer();
String temp = null;
for (int i = 0; i < bytes.length; i++) {
temp = Integer.toHexString(bytes[i] & 0xFF);
if (temp.length() == 1) {
// 1得到一位的进行补0操作
stringBuffer.append("0");
}
stringBuffer.append(temp);
}
return stringBuffer.toString();
}
public static String encodeBySHA256(String str) {
if (str == null) {
return null;
}
try {
MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
messageDigest.reset();
messageDigest.update(str.getBytes());
return getFormattedText(messageDigest.digest());
} catch (Exception e) {
return "";
}
}
private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
'e', 'f' };
private static String getFormattedText(byte[] bytes) {
int len = bytes.length;
StringBuilder buf = new StringBuilder(len * 2);
// 把密文转换成十六进制的字符串形式
for (int j = 0; j < len; j++) {
buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
}
return buf.toString();
}
}
