When Android connects to mySQL database through jdbc, the database refuses to connect

Cause:

mysql server For security reasons, the default user is only allowed to log in through the command line.

解决方案:

First login to the mysql server via localhost

Change the Host field of the root user in the user table of the mysql database of mysql server to "%".

 The operation is as follows: 
  1. window+r
  2. Enter the cmd command, hit enter
  3. Enter the command: mysql -h (localhost or 127.0.0.1) -u (username) -p (if there is a password, keep up with Your password)
  4. Enter the command: use mysql;
  5. Enter the command: update user set Host='%' where Host='localhost';
  6. Enter the command: flush privileges; (This command Must be executed, otherwise the configuration will not take effect)
  7. Enter the command: quit (exit)
    (Hint: Note that you need to add a semicolon after the command!)