spring boot启动后为什么没有在数据库中自动创建User表

application.properties:
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=rootspring.jpa.show-sql= true
spring.jpa.hibernate.ddl-auto=update
spring.jpa.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
spring.jackson.serialization.indent_output=false Application类：
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(HelloController.class, args);
    }
}User类：
package entity;import org.springframework.data.annotation.Id;import javax.persistence.*;
import javax.validation.constraints.NotNull;@Entity
@Table(name="usertable")
public class User {
   
    @Id
    @NotNull
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;    @NotNull
    @Column(name="user_name")
    private  String userName;    @NotNull
    @Column(name="user_password")
    private  String userPassword;    public User(){}    public User(String a, String b){
        this.userName = a;
        this.userPassword = b;
    }    public long getId() {
        return id;
    }    public void setId(long id) {
        this.id = id;
    }    public String getUserName() {
        return userName;
    }    public void setUserName(String userName) {
        this.userName = userName;
    }    public String getUserPassword() {
        return userPassword;
    }    public void setUserPassword(String userPassword) {
        this.userPassword = userPassword;
    }
}