微信公众平台获取access_token的方法步骤

{"access_token":"ACCESS_TOKEN","expires_in":7200}

{"errcode":40013,"errmsg":"invalid appid"}

/**
 * 类名: Token.java</br> 
 * 描述: 凭证</br> 
 */
public class Token {
  // 接口访问凭证
  private String accessToken;
  // 凭证有效期，单位：秒
  private int expiresIn;

  public String getAccessToken() {
    return accessToken;
  }

  public void setAccessToken(String accessToken) {
    this.accessToken = accessToken;
  }

  public int getExpiresIn() {
    return expiresIn;
  }

  public void setExpiresIn(int expiresIn) {
    this.expiresIn = expiresIn;
  }
}

  /**
   * 获取接口访问凭证
   * @param appid 凭证
   * @param appsecret 密钥
   * @return
   */
  public static Token getToken(String appid, String appsecret) {
    Token token = null;
    String requestUrl = WeixinConstants.TOKEN_URL.replace("APPID", appid).replace("APPSECRET", appsecret);
    // 发起GET请求获取凭证
    JSONObject jsonObject = httpsRequest(requestUrl, "GET", null);

    if (null != jsonObject) {
      try {
        token = new Token();
        token.setAccessToken(jsonObject.getString("access_token"));
        token.setExpiresIn(jsonObject.getInt("expires_in"));
      } catch (JSONException e) {
        token = null;
        // 获取token失败
        log.error("获取token失败 errcode:{} errmsg:{}", jsonObject.getInt("errcode"), jsonObject.getString("errmsg"));
      }
    }
    return token;
  }

  /**
   * 发送https请求
   * @param requestUrl 请求地址
   * @param requestMethod 请求方式（GET、POST）
   * @param outputStr 提交的数据
   * @return JSONObject(通过JSONObject.get(key)的方式获取json对象的属性值)
   */
  public static JSONObject httpsRequest(String requestUrl, String requestMethod, String outputStr) {
    JSONObject jsonObject = null;
    try {
      // 创建SSLContext对象，并使用我们指定的信任管理器初始化
      TrustManager[] tm = { new MyX509TrustManager() };
      SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");
      sslContext.init(null, tm, new java.security.SecureRandom());
      // 从上述SSLContext对象中得到SSLSocketFactory对象
      SSLSocketFactory ssf = sslContext.getSocketFactory();

      URL url = new URL(requestUrl);
      HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
      conn.setSSLSocketFactory(ssf);

      conn.setDoOutput(true);
      conn.setDoInput(true);
      conn.setUseCaches(false);
      // 设置请求方式（GET/POST）
      conn.setRequestMethod(requestMethod);

      // 当outputStr不为null时向输出流写数据
      if (null != outputStr) {
        OutputStream outputStream = conn.getOutputStream();
        // 注意编码格式
        outputStream.write(outputStr.getBytes("UTF-8"));
        outputStream.close();
      }

      // 从输入流读取返回内容
      InputStream inputStream = conn.getInputStream();
      InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
      BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
      String str = null;
      StringBuffer buffer = new StringBuffer();
      while ((str = bufferedReader.readLine()) != null) {
        buffer.append(str);
      }

      // 释放资源
      bufferedReader.close();
      inputStreamReader.close();
      inputStream.close();
      inputStream = null;
      conn.disconnect();
      jsonObject = JSONObject.fromObject(buffer.toString());
    } catch (ConnectException ce) {
      log.error("连接超时：{}", ce);
    } catch (Exception e) {
      log.error("https请求异常：{}", e);
    }
    return jsonObject;
  }

/**
 * 类名: MyX509TrustManager.java</br> 
 * 描述: 信任管理器</br> 
 */
public class MyX509TrustManager implements X509TrustManager {

  // 检查客户端证书
  public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
  }

  // 检查服务器端证书
  public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
  }

  // 返回受信任的X509证书数组
  public X509Certificate[] getAcceptedIssuers() {
    return null;
  }
}