加密算法 -- SHA-256

java的 SHA-256加密，几乎与 MD5加密的写法一样：

import java.security.MessageDigest; import java.util.Arrays;   public class Hello {     public static void main(String[] args) {         String name = 哈喽啊;         try {             MessageDigest instance = MessageDigest.getInstance(SHA-256);             // md5的加盐             instance.update(xxx.getBytes());             // md5加密的字节数组             byte[] nameBytes = instance.digest(name.getBytes());             System.out.println(Arrays.toString(nameBytes));// 打印结果：[-16, 34, -105, -18, -53, -91, 98, 48, -40, 115, 11, 25, 22, 7, -108, 5, 24, 51, -38, 36, 17, 94, -3, -102, -6, -76, -61, -77, -29, 4, 107, 84]              String res = new String(nameBytes);             System.out.println(res);              //创建一个可变字符串 sb             StringBuilder sb = new StringBuilder();             for (int i=0;i<nameBytes.length;i++){                 int val = nameBytes[i] & 255; //将负数转换成整数                 if (val < 16) {                     sb.append(0);                 }                 // 将val转换成16进制，再添加到sb这个可变的字符串中                 sb.append(Integer.toHexString(val));             }             //再将可变的字符串sb ,转换成不可变的字符串             String hexData = sb.toString();             System.out.println(hexData); // 打印结果：f02297eecba56230d8730b19160794051833da24115efd9afab4c3b3e3046b54          }catch (Exception e){             System.out.println(e);         }     } }