微信获取openId

	@Value("${wechat.appId}")
	private String appId;
	@Value("${wechat.appSecret}")
	private String appSecret;


/**
	 * 通过code获取判断openid
	 * 
	 * @param code
	 * @return
	 */
	public String getOpenid(String code) {
		try {
			String token_url = "https://api.weixin.qq.com/sns/oauth2/access_token";
			String params = "appid=" + appId + "&secret=" +appSecret + "&code=" + code + "&grant_type=authorization_code";
			String result = sendGet(token_url, params);
			JSONObject json = new JSONObject(result);
			Map map = new HashMap();
			if (json.has("openid")) {
				String openid = json.get("openid").toString();
				map.put("openid", openid);
				return write(200, "获取成功", "data", map);
			} else {
				return error(Integer.parseInt(json.get("errcode").toString()), "操作失败:" + json.get("errmsg").toString());
			}
		} catch (Exception e) {
			error(e);
			return invalidUserException(e, -1, "操作失败！");
		}
	}

/**
	 * 向指定URL发送GET方法的请求
	 *
	 * @param url
	 *            发送请求的URL
	 * @param param
	 *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
	 * @return URL 所代表远程资源的响应结果
	 */
	public  String sendGet(String url, String param) {
		String result = "";
		BufferedReader in = null;
		try {
			String urlNameString = url + "?" + param;
			URL realUrl = new URL(urlNameString);
			// 打开和URL之间的连接
			URLConnection connection = realUrl.openConnection();
			// 设置通用的请求属性
			connection.setRequestProperty("accept", "*/*");
			connection.setRequestProperty("connection", "Keep-Alive");
			connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
			// 建立实际的连接
			connection.connect();
			// 定义 BufferedReader输入流来读取URL的响应
			in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
			String line;
			while ((line = in.readLine()) != null) {
				result += line;
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (in != null) {
					in.close();
				}
			} catch (Exception e2) {
				e2.printStackTrace();
			}
		}
		return result;
	}