scauth/src/main/java/com/aiprose/scauth/util/JwtUtils.java

package com.aiprose.scauth.util;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class JwtUtils {

    /* 默认head */
    public static final String DEFAULT_HEADER = "{\"alg\": \"HS256\",\"typ\": \"JWT\"}";

    /* HmacSHA256 加密算法 秘钥 */
    public static final String SECRET = "12345";

    /* token有效时间  1天 */
    public static final long EXPIRE_TIME = 1000 * 60 * 60 * 24;

    /* token在header中的名字 */
    public static final String HEADER_TOKEN_NAME = "Authorization";

    /**
     * Base64URL 编码
     */
    public static String encode(String input) {
        return Base64.getUrlEncoder().encodeToString(input.getBytes());
    }

    /**
     * Base64URL 解码
     */
    public static String decode(String input) {
        return new String(Base64.getUrlDecoder().decode(input));
    }

    /**
     * HmacSHA256 加密算法
     *
     * @param data   要加密的数据
     * @param secret 秘钥
     */
    public static String HMACSHA256(String data, String secret) throws Exception {
        Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
        SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes("UTF-8"), "HmacSHA256");
        sha256_HMAC.init(secret_key);
        byte[] array = sha256_HMAC.doFinal(data.getBytes("UTF-8"));
        StringBuilder sb = new StringBuilder();
        for (byte item : array) {
            sb.append(Integer.toHexString((item & 0xFF) | 0x100), 1, 3);
        }
        return sb.toString().toUpperCase();
    }


    /**
     * 获取签名
     */
    public static String getSignature(String payload) throws Exception {
        return HMACSHA256(encode(DEFAULT_HEADER) + "." + encode(payload), SECRET);
    }


    /**
     * 验证jwt，正确返回载体数据，错误返回null
     *
     * @param jwt
     */
    public static String testJwt(String jwt) throws Exception {
        String[] jwts = jwt.split("\\.");

        /* 验证签名 */
        if (!HMACSHA256(jwts[0] + "." + jwts[1], SECRET).equals(jwts[2])) {
            return null;
        }
        /* 验证头部信息 */
        if (!jwts[0].equals(encode(DEFAULT_HEADER))) {
            return null;
        }
        return decode(jwts[1]);
    }
}