29.3.1 实体类

习惯上，JPA的“实体”类在persistence.xml文件中指定。Spring Boot使用“实体扫描”，此文件不是必需的。默认情况下，位于主配置类（一个被@EnableAutoConfiguration或@SpringBootApplication注解的类）下的所有包都会被搜索。

任何用@Entity、@Embeddable或@MappedSuperclass注解的类都会被考虑。典型的实体类会像这样：

package com.example.myapp.domain;

import java.io.Serializable;
import javax.persistence.*;

@Entity
public class City implements Serializable {

    @Id
    @GeneratedValue
    private Long id;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private String state;

    // ... additional members, often include @OneToMany mappings

    protected City() {
        // no-args constructor required by JPA spec
        // this one is protected since it shouldn't be used directly
    }

    public City(String name, String state) {
        this.name = name;
        this.country = country;
    }

    public String getName() {
        return this.name;
    }

    public String getState() {
        return this.state;
    }

    // ... etc

}

您可以使用@EntityScan注解自定义实体扫描位置。请参见第77.4节“从Spring配置中分离@Entity定义”的方法。