GWT与JDO问题

Question

我只是开始玩GWT，我很难让GWT + JAVA + JDO + Google
AppEngine与DataStore一起工作。我试图按照不同的教程学习，但是没有运气。例如，我喜欢这些教程：TUT1 TUT2

我无法弄清楚如何才能完成这项工作。请查看我的简单代码，并告诉我需要做什么，以便可以将其持久保存到数据存储区：

1.地址实体

package com.example.rpccalls.client;

import java.io.Serializable;

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

public class Address implements Serializable{

 @PrimaryKey
 @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
 private int addressID;
 @Persistent private String address1;
 @Persistent private String address2;
 @Persistent private String city;
 @Persistent private String state;
 @Persistent private String zip;

 public Address(){}

 public Address(String a1, String a2, String city, String state, String zip){
  this.address1 = a1;
  this.address2 = a2;
  this.city = city;
  this.state = state;
  this.zip = zip;
 }

 /* Setters and Getters */
}

2.个人实体

package com.example.rpccalls.client;

import java.io.Serializable;
import java.util.ArrayList;

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

import com.google.appengine.api.datastore.Key;

@PersistenceCapable
public class Person implements Serializable{

 @PrimaryKey
 @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
 private Key key;
 @Persistent private String name;
 @Persistent private int age;
 @Persistent private char gender;
 @Persistent ArrayList<Address> addresses;

 public Person(){}

 public Person(String name, int age, char gender){
  this.name = name;
  this.age = age;
  this.gender = gender;
 }

 /* Getters and Setters */
}

3. RPCCalls

package com.example.rpccalls.client;

import java.util.ArrayList;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;


public class RPCCalls implements EntryPoint {

 private static final String SERVER_ERROR = "An error occurred while attempting to contact the server. Please check your network connection and try again.";

 private final RPCCallsServiceAsync rpccallService = GWT.create(RPCCallsService.class);

 TextBox nameTxt = new TextBox();
 Button btnSave = getBtnSave();

 public void onModuleLoad() {

  RootPanel.get("inputName").add(nameTxt); 
  RootPanel.get("btnSave").add(btnSave);
 }



 private Button getBtnSave(){

  Button btnSave = new Button("SAVE");

  btnSave.addClickHandler(
    new ClickHandler(){
     public void onClick(ClickEvent event){
      saveData2DB(nameTxt.getText());
     }
    } 
  );
  return btnSave;
 }

 void saveData2DB(String name){  
  AsyncCallback<String> callback = new AsyncCallback<String>() {
   public void onFailure(Throwable caught) {
          Window.alert("WOOOHOOO, ERROR: " + SERVER_ERROR);
    // TODO: Do something with errors.
        }

        public void onSuccess(String result) {
          Window.alert("Server is saying: ' " + result + "'");
        }

  };

  ArrayList<Address> aa = new ArrayList<Address>();
  aa.add(new Address("123 sasdf","", "Some City", "AZ", "93923-2321"));
  aa.add(new Address("23432 asdf", "Appt 34", "Another City", "AZ", "43434-4432"));

  Person p = new Person();
  p.setName(name);
  p.setAge(23);
  p.setGender('m');
  p.setAddresses(aa);

  // !!!!!!!!!!!!!!!!!!  SERVER CALL !!!!!!!!!!!!!!!!!!
  rpccallService.saveName(p, callback);
  // !!!!!!!!!!!!!!!!!!  SERVER CALL !!!!!!!!!!!!!!!!!!

 }
}

4. RPCCallsService

package com.example.rpccalls.client;

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

@RemoteServiceRelativePath("calls")
public interface RPCCallsService extends RemoteService {

 String saveName(Person p);

}

5. RPCCallsServiceAsync

package com.example.rpccalls.client;

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

public interface RPCCallsServiceAsync {

 void saveName(Person p, AsyncCallback<String> callback);

}

6. RPCCalls.gwt.xml**

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 1.6.4//EN" "http://google-web-toolkit.googlecode.com/svn/tags/1.6.4/distro-source/core/src/gwt-module.dtd">
<module rename-to='rpccalls'>          
  <inherits name='com.google.gwt.user.User'/>
  <inherits name='com.google.gwt.user.theme.standard.Standard'/>
  <entry-point class='com.example.rpccalls.client.RPCCalls'/>
</module>

我试图在这些教程中添加Key类以及其他所有内容，但似乎我缺少了一些东西。

这是我的错误：
替代文字http://vasura.s3.amazonaws.com/Picture2.png

或在我收到此错误之前：

密钥无法解析为类型

使此工作最佳的解决方案是什么？

Answer 1

Sriram Narayan说要对密钥进行字符串编码，以使其通过GWT的RPC机制传递：

@PersistenceCapable(identityType = IdentityType.APPLICATION) public class SomeDomainClass implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true") String id;