Java 为什么我在Android中使用Google App Engile的端点插入数据时出错？

我正在从android项目访问端点。应用程序引擎项目已成功部署

这是我的Android代码：

Usermasterendpoint.Builder endpointBuilder = new 

Usermasterendpoint.Builder(AndroidHttp.newCompatibleTransport(),

           new JacksonFactory(),

           new HttpRequestInitializer() {

           public void initialize(HttpRequest httpRequest) { }

           });


            Usermasterendpoint endpoint = CloudEndpointUtils.updateBuilder(

        endpointBuilder).build();


            System.out.println("End of Asynk Task is...................///////////");

        try {

           UserMaster userManager = new UserMaster();//.setDescription("Note Description");

           String userID = new Date().toString();

           userManager.setUserID(userID);

           userManager.setEmail(Email);

           userManager.setUsername(username);

           userManager.setPassword(password);

           UserMaster UsermanagerResult = endpoint.insertUserMaster(userManager).execute();

09-04 14:42:55.946: W/System.err(1603): 

com.google.api.client.googleapis.json.GoogleJsonResponseException: 503 Service Unavailable

09-04 14:42:55.946: W/System.err(1603): {

09-04 14:42:55.946: W/System.err(1603):   "code" : 503,

09-04 14:42:55.946: W/System.err(1603):   "errors" : [ {

09-04 14:42:55.946: W/System.err(1603):     "domain" : "global",
09-04 14:42:55.956: W/System.err(1603):     "message" : "java.lang.NullPointerException",
09-04 14:42:55.956: W/System.err(1603):     "reason" : "backendError"
09-04 14:42:55.956: W/System.err(1603):   } ],
09-04 14:42:55.956: W/System.err(1603):   "message" : "java.lang.NullPointerException"
09-04 14:42:55.956: W/System.err(1603): }
09-04 14:42:55.956: W/System.err(1603):     at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:111)
09-04 14:42:55.956: W/System.err(1603):     at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:38)
09-04 14:42:55.986: W/System.err(1603):     at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:312)
09-04 14:42:55.986: W/System.err(1603):     at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1042)
09-04 14:42:55.986: W/System.err(1603):     at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:410)
09-04 14:42:55.986: W/System.err(1603):     at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:343)
09-04 14:42:55.986: W/System.err(1603):     at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:460)
09-04 14:42:55.996: W/System.err(1603):     at com.jagdish.mydprapp.model.UserManagerAccessorClass.doInBackground(UserManagerAccessorClass.java:57)
09-04 14:42:55.996: W/System.err(1603):     at com.jagdish.mydprapp.model.UserManagerAccessorClass.doInBackground(UserManagerAccessorClass.java:1)
09-04 14:42:56.007: W/System.err(1603):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
09-04 14:42:56.026: W/System.err(1603):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
09-04 14:42:56.026: W/System.err(1603):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
09-04 14:42:56.037: W/System.err(1603):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
09-04 14:42:56.037: W/System.err(1603):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
09-04 14:42:56.046: W/System.err(1603):     at java.lang.Thread.run(Thread.java:856)

这是我的UserMaster实体类。我正试图从上面的android代码中使用它。

package com.jay.myapp.dao;


//********************************************************************************************************* 
//Author - Jay
//Description - This class is Data Access Object (DAO) for UserMasterDao entity
//        - Class is basically business class and mostly related to GAE/web application
//*********************************************************************************************************

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import java.util.logging.Logger;

import com.google.appengine.api.users.User;
import com.jagdish.mydprapp.model.UserMaster;
import com.jagdish.mydprapp.model.EMF;

public enum UserMasterDao {

    INSTANCE;

    private static final Logger log = Logger.getLogger(UserMasterDao.class.getName());

//*****************************************************************************************************
//getUserByUsermasterID - This method will return List of users or user by getUserByUsermasterID
//*****************************************************************************************************

@SuppressWarnings("unchecked") //Suppress warning for getResultList()
public List<UserMaster> getUserByUsermasterID(Long usermasterID) {

log.info("Inside getUserByUsermasterID");  
EntityManager em = EMF.get().createEntityManager();
// Read the existing entries
Query q = em.createQuery("select t from UserMaster t where t.usermasterID = :usermasterID");
q.setParameter("usermasterID", usermasterID);
List<UserMaster> userlist = q.getResultList();
log.info("returning userlist");

return userlist;

}

//*****************************************************************************************************
//addUser - This method will add User to 
//*****************************************************************************************************

public void addUser(String userID, String employeeID, String mediamasterID, User user,
          String username, String password, String passwordhintquestion, String passwordhintanswer,
          String firstname, String lastname, String email, Long primaryphone, Long secondaryphone,
          Long primarymobile, Long secondarymobile, String gender, Long birthdate,
          String registrationID, String paypalID, String creditcardname, String creditcardnumber,
          String creditcardexpiration, String creditcardcvccode, String creditcardtype,
          boolean activeflag, String updatedby, String dateadded, String dateupdated, String comments) {

      synchronized (this) {
          log.info("Inside addUser");
          EntityManager em = EMF.get().createEntityManager();

          //get current date time
          Date date = new Date();
          SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy h:mm:ss a");
          String formattedDate = sdf.format(date);


          //using user1 object variable instead of user - conflict issue with constructor 
          UserMaster user1 = new UserMaster(userID,  employeeID,  mediamasterID, user,
                  username,  password,  passwordhintquestion,  passwordhintanswer,
                  firstname,  lastname,  email,  primaryphone,  secondaryphone,
                  primarymobile,  secondarymobile,  gender,  birthdate,
                  registrationID,  paypalID,  creditcardname,  creditcardnumber,
                  creditcardexpiration,  creditcardcvccode,  creditcardtype,
                  activeflag,  updatedby,  formattedDate,  formattedDate,  comments);

          em.persist(user1);
          em.close();
          log.info("User added to UserMaster" + user1);
      }
}


//*****************************************************************************************************
// createDefaultUser
//*****************************************************************************************************

public void createDefaultUser(User user, UserMaster appUser, GenericDao<UserMaster> userDao) {

    //get current date time
    Date date = new Date();
    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy h:mm:ss a");
    String formattedDate = sdf.format(date);

    log.info("current date time " + formattedDate);

    appUser = new UserMaster(user.getUserId(),"na","na",user, "na","na",
            "na", "na", user.getNickname(), "na", user.getEmail(), 0L, 0L,
          0L, 0L, "na", 0L, "na", user.getEmail(), "na", "na",
          "na", "na", "na", true, user.getUserId(), formattedDate, formattedDate, "na");

    userDao.put(appUser);

}




//*****************************************************************************************************
//removeUser - This method will remove User from table
//*****************************************************************************************************

public void removeUser(Long usermasterID) {
EntityManager em = EMF.get().createEntityManager();
try {
    log.info("Inside removeUser");
    UserMaster user = em.find(UserMaster.class, usermasterID);
    em.remove(user);
    log.info("User entry deleted");
} finally {
 em.close();
}
}



} //end of class

请帮我解决这个问题。

---

提前感谢

我得到了答案，你必须检查自动生成的id是否为空。这是我的第一次。我只需要在appengine项目的端点类中添加一个if语句。在endpoint类中，您将得到

containsYourEntityClass(YourEntityClass xyz) .

您必须添加

if(YourEntityClass.getxxxID() == null)
                return false;

整个代码是

private boolean containsYourEntityClass(YourEntityClass xyz) {
        EntityManager mgr = getEntityManager();
        boolean contains = true;
        try {
            if(xyz.getxxxID() == null)
                return false;
            YourEntityClass item = mgr.find(YourEntityClass.class,
                    xyz.getxxxID());
            if (item == null) {
                contains = false;
            }
        } finally {
            mgr.close();
        }
        return contains;
    }