### 29.3.1. 實體類 通常，JPA實體類被定義到一個`persistence.xml`文件，在Spring Boot中，這個文件被'實體掃描'取代。默認情況，Spring Boot會查找主配置類（被`@EnableAutoConfiguration`或`@SpringBootApplication`注解的類）下的所有包。 任何被`@Entity`，`@Embeddable`或`@MappedSuperclass`注解的類都將被考慮，一個普通的實體類看起來像這樣： ```java 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 } ``` **注** 你可以使用`@EntityScan`注解自定義實體掃描路徑，具體參考[Section 74.4, “Separate @Entity definitions from Spring configuration”](../IX. ‘How-to’ guides/74.4. Separate @Entity definitions from Spring configuration.md)。