有 JDO 问题的 GWT [英] GWT with JDO problem
问题描述
我刚开始使用 GWT 我真的很难让 GWT + JAVA + JDO + Google AppEngine 与 DataStore 一起工作.我试图遵循不同的教程，但没有运气.例如，我转到这些教程:TUT1 TUT2
I just start playing with GWT I'm having a really hard time to make GWT + JAVA + JDO + Google AppEngine working with DataStore. I was trying to follow different tutorial but had no luck. For example I wend to these tutorials: TUT1 TUT2
我无法弄清楚我需要做什么和做什么才能完成这项工作.请查看我的简单代码并告诉我我需要做什么才能将其持久化到数据存储区:
I was not able to figure out how and what i need to do in order to make this work. Please look at my simple code and tell me what do i need to do so i can persist it to the datastore:
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>
我尝试在这些教程中添加 Key 类和其他所有内容，但看起来我遗漏了一些东西.
I tried to add Key class and everything else in those tutorials but it looks like i'm missing something.
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:
or before i was getting this error:
键不能解析为类型
使这项工作发挥作用的最佳解决方案是什么?
What is the best solution to make this working?
推荐答案
Sriram Narayan 说对密钥进行字符串编码以使其通过 GWT 的 RPC 机制:
Sriram Narayan says to String-encode the Key to get it to pass through GWT's RPC mechanism:
<代码>@PersistenceCapable(identityType = IdentityType.APPLICATION)
公共类 SomeDomainClass 实现了 Serializable {
@主键
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true")
字符串 id;
这篇关于有 JDO 问题的 GWT的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
