使用rpc将gwt实体与jdo保存到Google应用程序引擎数据存储中

问题描述

你好，iam是GWT框架的新成员。我想使用rpc将我的域对象/实体保存到Google应用程序引擎数据存储中。一个简单的实现来测试我是否可以进行多个rpc调用（ greetServer（），saveStudent（））

Student

  import javax.jdo.annotations.Extension; 
 import javax.jdo.annotations.IdGeneratorStrategy; 
 import javax.jdo.annotations.PersistenceCapable; 
 import javax.jdo.annotations.Persistent; 
 import javax.jdo.annotations.PrimaryKey; 
 
 import com.google.gwt.user.client.rpc.IsSerializable; 
 
 @PersistenceCapable 
 public class Student实现IsSerializable {
 
 private static final long serialVersionUID = 1L; 
 
 @PrimaryKey 
 @Persistent（valueStrategy = IdGeneratorStrategy.IDENTITY）
 @Extension（vendorName =datanucleus，key =gae.encoded-pk，value =true ）
 private int studentId; 
 
 @Persistent private String firstName; 
 @Persistent private String lastName; 
 
 public Student（）{} 
 
 Student Student（String firstName，String lastName）{
 this.firstName = firstName; 
 this.lastName = lastName; 
} 
 
 public void setStudentId（int studentId）{
 this.studentId = studentId; 
} 
 
 public int getStudentId（）{
 return studentId; 
} 
 
 public void setFirstName（String firstName）{
 this.firstName = firstName; 
} 
 
 public String getFirstName（）{
 return firstName; 
} 
 
 public void setLastName（String lastName）{
 this.lastName = lastName; 
} 
 
 public String getLastName（）{
 return lastName; 
} 
} 
  

GreetingService （由Eclipse IDE生成的默认代码）

  import com.google.gwt.user.client.rpc.RemoteService ; 
 import com.google.gwt.user.client.rpc.RemoteServiceRelativePath; 
 
 @RemoteServiceRelativePath（greet）
 public interface GreetingService extends RemoteService {
 String greetServer（String name）throws IllegalArgumentException; 
 ** String saveStudent（Student's）throws IllegalArgumentException; ** 
} 
  

GreetingServiceAsync

  import com.google.gwt.user.client .rpc.AsyncCallback; 
 
 $ b public interface GreetingServiceAsync {
 void greetServer（String input，AsyncCallback< String> callback）
 throws IllegalArgumentException; 
 ** void saveStudent（Student's，AsyncCallback< String> callback）
 throws IllegalArgumentException; ** 
} 
  

$ b GreetingServiceImpl

  import javax.jdo.PersistenceManager; 
 
 import com.d.client.GreetingService; 
 import com.d.client.Student; 
 import com.d.shared.FieldVerifier; 
 import com.google.gwt.user.server.rpc.RemoteServiceServlet; 
 
 @SuppressWarnings（serial）
 public class GreetingServiceImpl extends RemoteServiceServlet implements 
 GreetingService {
 
 public String greetServer（String input）throws IllegalArgumentException 
 
 ... 
 
字符串serverInfo = getServletContext（）。getServerInfo（）; 
 String userAgent = getThreadLocalRequest（）。getHeader（User-Agent）; 
 
 ... 
 
} 
 
 
 @Override 
 public String saveStudent（Student's）throws IllegalArgumentException {
 PersistenceManager pm = PMF.get（）。getPersistenceManager（）; 
 pm.makePersistent（s）; 
返回学生保存 - 确定; 
} 
 
} 
  

PMF

  import javax.jdo.JDOHelper; 
 import javax.jdo.PersistenceManagerFactory; 
 
 public final class PMF {
 private static final PersistenceManagerFactory pmfInstance = JDOHelper 
 .getPersistenceManagerFactory（transactions-optional）; 
 
 private PMF（）{$​​ b $ b} 
 
 public static PersistenceManagerFactory get（）{
 return pmfInstance; 
 
 
  

  ... 
 
 private final GreetingServiceAsync greetingService = GWT 
。创建（GreetingService.class）; 
 
 greetingService.greetServer（greet，
 new AsyncCallback< String>（）{
 public void onFailure（Throwable caught）{
 //显示RPC错误给用户的消息
} 
 
 public void onSuccess（String result）{
 //显示成功消息
} 
}）; 
 
 greetingService.saveStudent（新学生（kostas，trichas），
新增AsyncCallback< String>（）{
 public void onFailure（Throwable caught）{
 //向用户显示RPC错误消息
 
 $ b public void onSuccess（String result）{
 //显示成功消息
} 
}）; 
 
 ... 
  

上述实施是否正确？我将这个示例应用程序部署到gae，并且它没有保留对象 student （您可以在gae datastore查看器中浏览实体）

http：//gwtgaedatastore.appspot。

解决方案

更改您的int studentID为Long id以使其正常工作

Hello iam new to GWT framework. I want to persist my domain objects/entities to google application engine datastore using rpc. A simple implementation to test if i can make multiple rpc calls ( greetServer() , saveStudent() )

Student

import javax.jdo.annotations.Extension;
import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

import com.google.gwt.user.client.rpc.IsSerializable;

@PersistenceCapable
public class Student implements IsSerializable  {

private static final long serialVersionUID = 1L;

 @PrimaryKey
 @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
 @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true")
 private int studentId;

 @Persistent private String firstName;
 @Persistent private String lastName;

public Student(){}

 public Student(String firstName, String lastName){
  this.firstName = firstName;
  this.lastName  = lastName;
 }

 public void setStudentId(int studentId) {
  this.studentId = studentId;
 }

 public int getStudentId() {
  return studentId;
 }

 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 public String getFirstName() {
  return firstName;
 }

 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

 public String getLastName() {
  return lastName;
 }
}

GreetingService (default code generated by Eclipse IDE)

import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;

@RemoteServiceRelativePath("greet")
public interface GreetingService extends RemoteService {
 String greetServer(String name) throws IllegalArgumentException;
 **String saveStudent(Student s) throws IllegalArgumentException;**
}

GreetingServiceAsync

import com.google.gwt.user.client.rpc.AsyncCallback;


public interface GreetingServiceAsync {
 void greetServer(String input, AsyncCallback<String> callback)
   throws IllegalArgumentException;
 **void saveStudent(Student s, AsyncCallback<String> callback)
   throws IllegalArgumentException;**
}

GreetingServiceImpl

import javax.jdo.PersistenceManager;

import com.d.client.GreetingService;
import com.d.client.Student;
import com.d.shared.FieldVerifier;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;

@SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet implements
  GreetingService {

 public String greetServer(String input) throws IllegalArgumentException

  ...

  String serverInfo = getServletContext().getServerInfo();
  String userAgent = getThreadLocalRequest().getHeader("User-Agent");

  ...

 }


 @Override
 public String saveStudent(Student s) throws IllegalArgumentException {
  PersistenceManager pm = PMF.get().getPersistenceManager();
  pm.makePersistent(s);
  return "student save - ok";
  }

 }

PMF

import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManagerFactory;

public final class PMF {
    private static final PersistenceManagerFactory pmfInstance = JDOHelper
            .getPersistenceManagerFactory("transactions-optional");

    private PMF() {
    }

    public static PersistenceManagerFactory get() {
        return pmfInstance;
    }
}

EntryPoint

...

private final GreetingServiceAsync greetingService = GWT
    .create(GreetingService.class);

    greetingService.greetServer("greet",
      new AsyncCallback<String>() {
       public void onFailure(Throwable caught) {
        // Show the RPC error message to the user
       }

       public void onSuccess(String result) {
        //Show success message
       }
      });

    greetingService.saveStudent(new Student("kostas","trichas"),
      new AsyncCallback<String>() {
       public void onFailure(Throwable caught) {
        // Show the RPC error message to the user
       }

       public void onSuccess(String result) {
        //Show success message
       }
      });

   ...

Is the above implementation correct? I deployed this sample application to gae and it did not persisted the object student (you can browse the entities at gae datastore viewer)

check it please:

http://gwtgaedatastore.appspot.com

解决方案

Change your int studentID to Long id to get it working

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