云sql

Question

有时，我在使用云SQL连接时出现通信失败错误。这是错误详细信息：

{ "error": {"errors": [   {
"domain": "global",    "reason": "backendError",
"message": "com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure\n\nThe last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server."   }  ],  "code": 503,  "message": "com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure\n\nThe last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server." }}

请帮助我。

我的java代码是：

 Class.forName ("com.mysql.jdbc.GoogleDriver");
con  = DriverManager.getConnection("<< connections , username,password>>");
java.sql.Statement stmt = con.createStatement();
String sqlpost = "<<  here is mysql query>>";
ResultSet rst = stmt.executeQuery(sqlpost);
int count = 0;
while (rst.next()) {
Users users = new Users(rst.getInt("id"), rst.getString("altername"));
friendlist.add(users);
}
con.close ();