AndroidStudio / gradle找不到javax.persistence包

问题描述

尝试执行以下教程时：

使用Android Studio创建了一个Android Studio项目并添加了CheckIn.java类，其中包含以下内容：

  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; 
私人字符串placeId; 
私人字符串userEmail; 
私人日期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，当我尝试在Android Studion / gradle项目中构建项目时，出现以下错误：

 错误：（6 ，25）错误：程序包javax.persistence不存在
错误：（7，25）错误：程序包javax.persistence不存在
错误：（8,25）错误：程序包javax.persistence不存在
错误：（9，25）错误：程序包javax.persistence不存在
错误：（11，2）错误：找不到符号类实体
错误：（14，6 ）错误：无法找到符号类Id 
错误：（15，6）错误：无法找到符号类GeneratedValue 
错误：（6，25）错误：程序包javax.persistence不存在
错误：（7,25）错误：程序包javax.persistence不存在
错误：（8,25）错误：程序包javax.persistence不存在
错误：（9，25）错误：程序包javax.persistence不存在
错误：（11，2）错误：找不到符号类实体
错误：（14，6）错误：无法找到s ymbol class Id 
错误：（15，6）错误：无法找到符号类GeneratedValue 
  

解决方案

当我添加时，它得到了修复：

 编译组：'javax.persistence'，名称：'persistence-api'，版本：'1.0'
  

指向我的gradle依赖关系。如所述。

While attempting to do the following tutorial :

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

using Android Studio, I created an Android Studio project and added the CheckIn.java class with the following contents :

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;
}

}

But when I try to build the project in my Android Studion / gradle project, I get the following errors :

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

解决方案

This got fixed when I added:

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

to my gradle dependencies. As described here.

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