AndroidStudio / gradle找不到javax.persistence包

Question

在尝试执行以下教程时：

https://cloud.google.com/developers/articles/how-to-build-mobile-app-with-app-engine-backend-tutorial/

使用Android，我创建了一个Android项目，并添加了包含以下内容的CheckIn.java类：

import java.util.Date;
import com.google.appengine.api.datastore.Key;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class CheckIn {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private java.security.Key key;
private String placeId;
private String userEmail;
private Date checkinDate;

public java.security.Key getKey() {
    return key;
}

public String getPlaceId() {
    return placeId;
}
public void setPlaceId(String placeId) {
    this.placeId = placeId;
}

public String getUserEmail() {
    return userEmail;
}
public void setUserEmail(String userEmail) {
    this.userEmail = userEmail;
}

public Date getCheckinDate() {
    return checkinDate;
}
public void setCheckinDate(Date date) {
    checkinDate = date;
}

}

但是，当我试图在Android / gradle项目中构建该项目时，我会得到以下错误：

Error:(6, 25) error: package javax.persistence does not exist
Error:(7, 25) error: package javax.persistence does not exist
Error:(8, 25) error: package javax.persistence does not exist
Error:(9, 25) error: package javax.persistence does not exist
Error:(11, 2) error: cannot find symbol class Entity
Error:(14, 6) error: cannot find symbol class Id
Error:(15, 6) error: cannot find symbol class GeneratedValue
Error:(6, 25) error: package javax.persistence does not exist
Error:(7, 25) error: package javax.persistence does not exist
Error:(8, 25) error: package javax.persistence does not exist
Error:(9, 25) error: package javax.persistence does not exist
Error:(11, 2) error: cannot find symbol class Entity
Error:(14, 6) error: cannot find symbol class Id
Error:(15, 6) error: cannot find symbol class GeneratedValue

Answer 1

当我说：

compile group: 'javax.persistence', name: 'persistence-api', version: '1.0'

到我的梯度依赖项。正如所描述的here。