/**
 * 微信服务调用接口
 */
@Controller
@RequestMapping("/wechat")
public class WeChatTest {
    private static String wxToken="flzabc123";
    @GetMapping("")
    public void weChatTestV(HttpServletRequest request, HttpServletResponse response) {
        // 1、验证消息的确来自微信服务器
        String signature = request.getParameter("signature");
        String timestamp = request.getParameter("timestamp");
        String nonce = request.getParameter("nonce");
        String echostr = request.getParameter("echostr");
        //将微信echostr返回给微信服务器
        try(OutputStream os = response.getOutputStream()) {
            String sha1 = getSHA1(wxToken, timestamp, nonce, "");
            //和signature进行对比
            if (sha1.equals(signature)){
            // 返回echostr给微信
                os.write(URLEncoder.encode(echostr, "UTF-8").getBytes());
                os.flush();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 用SHA1算法生成安全签名
     *
     * @param token     票据
     * @param timestamp 时间戳
     * @param nonce     随机字符串
     * @param encrypt   密文
     * @return 安全签名
     * @throws Exception
     */
    public static String getSHA1(String token, String timestamp, String nonce, String encrypt) throws Exception {
        try {
            String[] array = new String[]{token, timestamp, nonce, encrypt};
            StringBuffer sb = new StringBuffer();
            // 字符串排序
            Arrays.sort(array);
            for (int i = 0; i < 4; i++) {
                sb.append(array[i]);
            }
            String str = sb.toString();
            // SHA1签名生成
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            md.update(str.getBytes());
            byte[] digest = md.digest();
            StringBuffer hexstr = new StringBuffer();
            String shaHex = "";
            for (int i = 0; i < digest.length; i++) {
                shaHex = Integer.toHexString(digest[i] & 0xFF);
                if (shaHex.length() < 2) {
                    hexstr.append(0);
                }
                hexstr.append(shaHex);
            }
            return hexstr.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }
}