# 29.3.1. 实体类

通常，JPA实体类被定义到一个`persistence.xml`文件，在Spring Boot中，这个文件被'实体扫描'取代。默认情况，Spring Boot会查找主配置类（被`@EnableAutoConfiguration`或`@SpringBootApplication`注解的类）下的所有包。

任何被`@Entity`，`@Embeddable`或`@MappedSuperclass`注解的类都将被考虑，一个普通的实体类看起来像这样：

```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`注解自定义实体扫描路径，具体参考[Section 74.4, “Separate @Entity definitions from Spring configuration”](https://github.com/cwiki-us-spring-guides/Spring-Boot-Reference-Guide/tree/0047aa8098a650dde0c93f4d2e91754c83468c4b/IX.%20%E2%80%98How-to%E2%80%99%20guides/74.4.%20Separate%20@Entity%20definitions%20from%20Spring%20configuration.md)。
