curl-fsSL https://get.docker.com | bash-s docker --mirror Aliyun
systemctl start docker

docker run -d--name some-polardb-x -p8527:8527 polardbx/polardb-x:2.1.0

yum install mysql -y

mysql -V

mysql -h127.0.0.1 -P8527-upolardbx_root-p123456

yum -y install java-1.8.0-openjdk*
java -version

yum -y install git

git clone https://github.com/spring-guides/gs-accessing-data-mysql.git

cd gs-accessing-data-mysql/initial
git checkout b8408e3a1e05008811d542b706107d45160556ac
ls

mysql -h127.0.0.1 -P8527-upolardbx_root-p123456create database db_example;
create user 'springuser'@'%' identified by 'ThePassword';
grant all on db_example.* to 'springuser'@'%';

vim src/main/resources/application.properties

vim src/main/java/com/example/accessingdatamysql/User.java
package com.example.accessingdatamysql;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity // This tells Hibernate to make a table out of this class
public class User {
  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  private Integer id;
  private String name;
  private String email;
  public Integer getId() {
    return id;
  }
  public void setId(Integer id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public String getEmail() {
    return email;
  }
  public void setEmail(String email) {
    this.email = email;
  }
}

vim src/main/java/com/example/accessingdatamysql/UserRepository.java
package com.example.accessingdatamysql;
import org.springframework.data.repository.CrudRepository;
import com.example.accessingdatamysql.User;
// This will be AUTO IMPLEMENTED by Spring into a Bean called userRepository
// CRUD refers Create, Read, Update, Delete
public interface UserRepository extends CrudRepository<User, Integer> {
}

vim src/main/java/com/example/accessingdatamysql/MainController.java
package com.example.accessingdatamysql;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller // This means that this class is a Controller
@RequestMapping(path="/demo") // This means URL's start with /demo (after Application path)public class MainController {  @Autowired // This means to get the bean called userRepository         // Which is auto-generated by Spring, we will use it to handle the data  private UserRepository userRepository;  @PostMapping(path="/add") // Map ONLY POST Requests  public @ResponseBody String addNewUser (@RequestParam String name      , @RequestParam String email) {    // @ResponseBody means the returned String is the response, not a view name    // @RequestParam means it is a parameter from the GET or POST request    User n = new User();    n.setName(name);    n.setEmail(email);    userRepository.save(n);    return "Saved";  }  @GetMapping(path="/all")  public @ResponseBody Iterable<User> getAllUsers() {    // This returns a JSON or XML with the users    return userRepository.findAll();  }}

./gradlew bootRun

curl localhost:8080/demo/add -dname=First -demail=username@example.com

curl'localhost:8080/demo/all'

mysql -h127.0.0.1 -P8527-upolardbx_root-p123456use db_example;
select * from user;