@RestController
@RequestMapping("/weixin")
public class WeiXinDemoController {
  @Autowired
  private WeiXinService weiXinService;

  @RequestMapping("/getWeiXinUserInfo")
  public String getWeiXinUserInfo(String code,HttpServletRequest request,HttpServletResponse response,HttpSession session) throws IOException{
    //第一步：用戶(hù)同意授權(quán)，獲取code
    if (code == null) {
      String url = URLEncoder.encode(request.getRequestURL().toString());
      String authorizeUrl = weiXinService.buildAuthorizeURL(url);
      response.sendRedirect(authorizeUrl);
      return null;
    }
    //第二步：通過(guò)code換取網(wǎng)頁(yè)授權(quán)access_token和openid
    String htmlInfo = "";
    Map<String, Object> openIdInfo = weiXinService.getOpenIdInfo(code);
    String errcode = (String)openIdInfo.get("errcode");
    if(StringUtils.isEmpty(errcode)){
      //第四步：拉取用戶(hù)信息(需scope為 snsapi_userinfo)根據(jù)access_token和OpenId
      Map<String, Object> weiXinUserInfo = weiXinService.getWeiXinUserInfo(openIdInfo);
      String userInfohtml = createUserInfoHtml(weiXinUserInfo);
      return userInfohtml;
    }
    return htmlInfo;
  }

@Component
@ConfigurationProperties(prefix="wx")
public class WeiXinConfig {
  
  private String appID;
  private String mchID;
  private String appsecret;
  private String key;
  
  //省略getter and setter
}

  /**
   * 拼接用戶(hù)授權(quán)重定向的URL
   * @param url
   * @return
   */
  public String buildAuthorizeURL(String url){
    
    return concatAuthorizeURL(url);
  }
    private String concatAuthorizeURL(String url) {
    StringBuilder authorizeUrl = new StringBuilder(AUTHORIZEURL);
    authorizeUrl.append("?appid=").append(weiXinConfig.getAppID());
    authorizeUrl.append("&redirect_uri=").append(url);
    authorizeUrl.append("&response_type=code");
     //snsapi_base （不彈出授權(quán)頁(yè)面，直接跳轉(zhuǎn)，只能獲取用戶(hù)openid），
     //snsapi_userinfo （彈出授權(quán)頁(yè)面，可通過(guò)openid拿到昵稱(chēng)、性別、所在地。并且， 即使在未關(guān)注的情況下，只要用戶(hù)授權(quán)，也能獲取其信息 ）
    authorizeUrl.append("&scope=snsapi_userinfo");
    authorizeUrl.append("&state=").append("STATE");
    authorizeUrl.append("#wechat_redirect");
    return authorizeUrl.toString();
  }

  /**
   * 獲取 access_token 和 openid
   * @param code
   * @return
   */
  public Map<String,Object> getOpenIdInfo(String code){
    
    String getAccessTokenUrl = concatGetOpenIdInfoURL(code);
    String json = postRequestForWechat(getAccessTokenUrl);
    Map<String,Object> map = jsonToMap(json);
    
    return map;
  }
  private String concatGetOpenIdInfoURL(String code) {
    StringBuilder getAccessTokenUrl = new StringBuilder(GE_TACCESSTOKEN_URL);
    getAccessTokenUrl.append("?appid=").append(weiXinConfig.getAppID());
    getAccessTokenUrl.append("&secret=").append(weiXinConfig.getAppsecret());
    getAccessTokenUrl.append("&code=").append(code);
    getAccessTokenUrl.append("&grant_type=authorization_code");
    return getAccessTokenUrl.toString();
  }
  private String postRequestForWechat(String getAccessTokenUrl) {
    ResponseEntity<String> postForEntity = restTemplate.postForEntity(getAccessTokenUrl, null, String.class);
    String json = postForEntity.getBody();
    return json;
  }
    private Map jsonToMap(String json) {
    Gson gons = new Gson();
    Map map = gons.fromJson(json, new TypeToken<Map>(){}.getType());
    return map;
  }

  /**
   * 獲取微信用戶(hù)信息通過(guò) access_token 和 openid
   * @param map
   * @return
   */
  public Map getWeiXinUserInfo(Map<String, Object> map) {
    
    String getUserInfoUrl = concatGetWeiXinUserInfoURL(map);
    String json = getRequestForWechat(getUserInfoUrl);
    Map userInfoMap = jsonToMap(json);
    
    return userInfoMap;
  }
    private String concatGetWeiXinUserInfoURL(Map<String, Object> map) {
    String openId = (String) map.get("openid");
    String access_token = (String) map.get("access_token");
    // 繞過(guò)檢驗(yàn)授權(quán)憑證（access_token）是否有效
    StringBuilder getUserInfoUrl = new StringBuilder(GE_USERINFO_URL);
    getUserInfoUrl.append("?access_token=").append(access_token);
    getUserInfoUrl.append("&openId=").append(openId);
    getUserInfoUrl.append("&lang=zh_CN");
    
    return getUserInfoUrl.toString();
  }
  private String getRequestForWechat(String getUserInfoUrl) {
    ResponseEntity<String> postForEntity = restTemplate.getForEntity(getUserInfoUrl.toString(), String.class);
    String json = postForEntity.getBody();
    return json;
  }