我一直在尝试使用mvp4g framework构建一个GWT / Google App Engine网络应用。
我一直收到错误无法通过延期绑定创建我的服务实例。
我的Acebankroll.gwt.xml文件如下：
<?xml version="1.0" encoding="UTF-8"?>
<module rename-to='acebankroll'>
<inherits name='com.google.gwt.user.User'/>
<inherits name="com.google.gwt.i18n.I18N"/>
<inherits name='com.google.gwt.user.theme.standard.Standard'/>
<inherits name='com.mvp4g.Mvp4gModule'/>
<entry-point class='com.softamo.acebankroll.client.AceBankroll'/>
<source path='client'/>
</module>
我的输入模块如下：
public class AceBankroll implements EntryPoint {
public void onModuleLoad() {
Mvp4gModule module = (Mvp4gModule)GWT.create( Mvp4gModule.class );
module.createAndStartModule();
RootPanel.get().add((Widget)module.getStartView());
}
}
我发布了完整的错误跟踪作为答案。
我已经读过，下一个常见错误列表可能会导致此错误：
ServiceAsync接口具有返回值的方法。这是错误的，所有方法都需要返回void。
Service接口不扩展RemoteService接口。
ServiceAsync接口中的方法错过了AsyncCallback的最终参数。
两个interfaced，ExampleService和ExampleServiceAsync上的方法不完全匹配（除了返回值和AsyncCallback参数）
我检查了上述所有条件，但没有发现问题。
这是一个片段，说明我如何在我的演示者类中注入服务。
protected MainServiceAsync service = null;
@InjectService
public void setService( MainServiceAsync service ) {
this.service = service;
}
是的，我的lib目录中有commons-configuration-1.6.jar，commons-lang-2.4.jar和mvp4g-1.1.0.jar。
是的，确实可以编译。我使用Eclipse和GWT / Google App Engine插件。接下来我发布我的.classpath
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="src" path="src"/>
<classpathentry kind="src" output="test-classes" path="test"/>
<classpathentry kind="con" path="com.google.appengine.eclipse.core.GAE_CONTAINER"/>
<classpathentry kind="con" path="com.google.gwt.eclipse.core.GWT_CONTAINER"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
<classpathentry kind="lib" path="lib/commons-configuration-1.6.jar"/>
<classpathentry kind="lib" path="lib/commons-lang-2.4.jar"/>
<classpathentry kind="lib" path="lib/mvp4g-1.1.0.jar"/>
<classpathentry kind="lib" path="test/lib/emma.jar"/>
<classpathentry kind="lib" path="test/lib/junit-4.5.jar"/>
<classpathentry kind="lib" path="C:/Users/sdelamo/Programms/eclipse/plugins/com.google.appengine.eclipse.sdkbundle.1.3.1_1.3.1.v201002101412/appengine-java-sdk-1.3.1/lib/testing/appengine-testing.jar"/>
<classpathentry kind="lib" path="C:/Users/sdelamo/Programms/eclipse/plugins/com.google.appengine.eclipse.sdkbundle.1.3.1_1.3.1.v201002101412/appengine-java-sdk-1.3.1/lib/impl/appengine-api.jar"/>
<classpathentry kind="lib" path="C:/Users/sdelamo/Programms/eclipse/plugins/com.google.appengine.eclipse.sdkbundle.1.3.1_1.3.1.v201002101412/appengine-java-sdk-1.3.1/lib/impl/appengine-api-labs.jar"/>
<classpathentry kind="lib" path="C:/Users/sdelamo/Programms/eclipse/plugins/com.google.appengine.eclipse.sdkbundle.1.3.1_1.3.1.v201002101412/appengine-java-sdk-1.3.1/lib/impl/appengine-api-stubs.jar"/>
<classpathentry kind="lib" path="C:/Users/sdelamo/Programms/eclipse/plugins/com.google.appengine.eclipse.sdkbundle.1.3.1_1.3.1.v201002101412/appengine-java-sdk-1.3.1/lib/impl/appengine-local-runtime.jar"/>
<classpathentry kind="output" path="war/WEB-INF/classes"/>
</classpath>
是的，它们是可序列化的。他们实现了下一个界面：
public interface BasicBean extends Serializable {
public String getId();
public void copy(BasicBean ob);
}
它们都有一个空参数构造函数。其中一些有两个构造函数。一个没有参数，一个没有参数。
其中一些实现此接口
public interface NameObject extends BasicBean, BaseOwnedObject, Comparable<NameObject> {
public String getName();
public void setName(String name);
public abstract int compareTo(NameObject ob);
}
Comparable会导致问题吗？
我发布了我的服务代码：
@RemoteServiceRelativePath( "main" )
public interface MainService extends RemoteService {
public List<UserBean> getUsers();
public void deleteUser(UserBean user);
public void createUser(UserBean user);
public void updateUser( UserBean user );
public String authenticate(String username, String password);
public boolean isSessionIdStillLegal(String sessionId);
public void signOut();
public boolean userAlreadyExists(String email);
public UserBean getByEmail(String email);
public void confirmUser(String email);
public UserBean getUserById(String id);
}
public interface MainServiceAsync {
public void getUsers(AsyncCallback<List<UserBean>> callback);
public void deleteUser(UserBean user, AsyncCallback<Void> callback);
public void createUser(UserBean user, AsyncCallback<Void> callback);
public void updateUser( UserBean user, AsyncCallback<Void> callback);
public void authenticate(String username, String password, AsyncCallback<String> callback);
public void isSessionIdStillLegal(String sessionId, AsyncCallback<Boolean> callback);
public void signOut(AsyncCallback<Void> callback);
public void userAlreadyExists(String email, AsyncCallback<Boolean> callback);
public void getByEmail(String email, AsyncCallback<UserBean> callback );
public void confirmUser(String email, AsyncCallback<Void> callback );
public void getUserById(String id, AsyncCallback<UserBean> callback);
}
import java.io.Serializable;
public interface BasicBean extends Serializable {
public String getId();
public void copy(BasicBean ob);
}
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class UserBean implements BasicBean {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
protected Long ident;
@Persistent
private String name = null;
@Persistent
private String email = null;
@Persistent
private boolean confirmed = false;
@Persistent
private String password = null;
public UserBean() { }
public String getId() {
if( ident == null ) return null;
return ident.toString();
}
public void setId(String id) {
this.ident = Long.parseLong(id);
}
public String getEmail( ) { return email; }
public void setEmail(String email) { this. email = email; }
public String getName() { return name; }
public void setName(String name) { this. name = name; }
public String getPassword() { return password; }
public void setPassword(String password) { this.password = password;}
public boolean isConfirmed() { return confirmed;}
public void setConfirmed(boolean confirmed) {this.confirmed = confirmed;}
public void copy(BasicBean ob) {
UserBean user = (UserBean) ob;
this.name = user.name;
this.email = user.email;
this.password = user.password;
}
}
接下来我发布web.xml的摘录 注意。我有7个其他服务。我正在使用MVP4G的模块功能。我在web.xml中为每个模块定义了其他servlet
<servlet>
<servlet-name>mainServlet</servlet-name>
<servlet-class>com.softamo.acebankroll.server.MainServiceImpl</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>mainServlet</servlet-name>
<url-pattern>/acebankroll/main</url-pattern>
</servlet-mapping>
public abstract class BaseServiceImpl extends RemoteServiceServlet {
protected Map users = new HashMap();
protected static final MemcacheService memcache = MemcacheServiceFactory.getMemcacheService();
protected static final Logger log = Logger.getLogger(BaseServiceImpl.class.getName());
protected String getSessionId() {
return getThreadLocalRequest().getSession().getId();
}
protected String getCurrentUserId() {
String id = getSessionId();
UserBean user = (UserBean) users.get(id);
if(user!=null)
return user.getId();
return null;
}
protected void saveBaseObject(BasicBean ob) {
PersistenceManager pm = JdoUtil.getPm();
String sessionId = getSessionId();
UserBean user = (UserBean) users.get(sessionId);
if(user!=null) {
String user_id = user.getId();
((BaseOwnedObject)ob).setUserId(user_id);
pm.makePersistent(ob);
}
}
protected void deleteBaseObject(Class classname, String id) {
PersistenceManager pm = JdoUtil.getPm();
pm.deletePersistent( pm.getObjectById(classname, Long.parseLong(id) ));
}
protected List getAll(Class class_name) {
PersistenceManager pm = JdoUtil.getPm();
pm.setDetachAllOnCommit(true);
Query q = pm.newQuery(class_name);
if(q==null)
return new ArrayList<BasicBean>();
q.setFilter("userId == userIdParam");
q.declareParameters("String userIdParam");
String userId = getCurrentUserId();
return (List) q.execute(userId);
}
public boolean isSessionIdStillLegal(String sessionId) {
return (users.containsKey(sessionId))? true : false;
}
public void signOut() {
String id = getSessionId();
synchronized(this) {
users.remove(id);
}
}
public BasicBean getObjectById(Class classname, String id) {
BasicBean result = null;
PersistenceManager pm = JdoUtil.getPm();
pm.setDetachAllOnCommit(true);
result = pm.getObjectById(classname, Long.parseLong(id) );
return result;
}
}
public class MainServiceImpl extends BaseServiceImpl implements MainService {
public MainServiceImpl() {}
public String authenticate(String username, String password) {
PersistenceManager pm = JdoUtil.getPm();
UserBean user = getByEmail(username);
if(user==null || !user.isConfirmed())
return null;
String hashFromDB = user.getPassword();
boolean valid = BCrypt.checkpw(password, hashFromDB);
if(valid) {
String id = getSessionId();
synchronized( this ) {
users.put(id, user) ;
}
return id;
}
return null;
}
public void deleteUser(UserBean user) {
deleteBaseObject(UserBean.class, user.getId());
}
public List<UserBean> getUsers() {
PersistenceManager pm = JdoUtil.getPm();
pm.setDetachAllOnCommit(true);
Query q = pm.newQuery(UserBean.class);
if(q==null)
return new ArrayList<UserBean>();
return (List) q.execute();
}
public boolean userAlreadyExists(String email) {
return (getByEmail(email)!=null) ? true : false;
}
public void updateUser(UserBean object) {
saveBaseObject(object);
}
public void confirmUser(String email) {
PersistenceManager pm = JdoUtil.getPm();
UserBean user = getByEmail(email);
if(user!=null) {
user.setConfirmed(true);
pm.makePersistent(user);
}
}
public void createUser(UserBean user) {
PersistenceManager pm = JdoUtil.getPm();
String sessionId = getSessionId();
// Only store it if it does not exists
if( (getByEmail(user.getEmail()))==null) {
String hash = BCrypt.hashpw(user.getPassword(), BCrypt.gensalt());
user.setPassword(hash);
pm.makePersistent(user);
synchronized( this ) {
users.put(sessionId, user);
}
}
}
public UserBean getByEmail(String email) {
return new MyAccountServiceImpl().getByEmail(email);
}
public UserBean getUserById(String id) {
return new MyAccountServiceImpl().getUserById(id);
}
}
显然，我的Bean类中的Google App Engine注释导致了这个问题。从客户端代码中删除注释解决了该问题。我知道如果我在服务器端有JDO表示法的类。也就是说bean是普通的数据传输对象，它在服务器端用JDO注释克隆到对象中。
我确实堆积如山。我不知道该尝试什么。任何帮助都非常感谢！
答案 0 :(得分：6)
如果您的服务方法包含POJO，它们可能会导致您遇到问题，它们必须具有零参数构造函数或未定义构造函数。他们还必须实现IsSerializable或Serializable。
您可以使用以下方法手动创建服务：
MainServiceAsync service = GWT.create(MainService.class);
也许发布MainService类。
编辑：
这是来自treelogger的输出，延迟绑定失败，当你进行gwt编译时，它会输出到控制台中。如果在托管模式下运行，您还可以在devmode控制台中看到此输出。始终检查第一个错误，因为其他错误是由第一个错误引起的。
Compiling module se.pathed.defa.DefaultGwtProject
Scanning for additional dependencies: file:/C:/Users/Patrik/workspace/skola-workspace/DefaultGwtProject/src/se/pathed/defa/client/DefaultGwtProject.java
Computing all possible rebind results for 'se.pathed.defa.client.GreetingService'
Rebinding se.pathed.defa.client.GreetingService
Invoking com.google.gwt.dev.javac.StandardGeneratorContext@16c6a55
Generating client proxy for remote service interface 'se.pathed.defa.client.GreetingService'
[ERROR] se.pathed.defa.shared.UserBean is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via se.pathed.defa.shared.UserBean)
[ERROR] se.pathed.defa.shared.UserBean has no available instantiable subtypes. (reached via se.pathed.defa.shared.UserBean)
[ERROR] subtype se.pathed.defa.shared.UserBean is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via se.pathed.defa.shared.UserBean)
[ERROR] Errors in 'file:/C:/Users/Patrik/workspace/skola-workspace/DefaultGwtProject/src/se/pathed/defa/client/DefaultGwtProject.java'
[ERROR] Line 37: Failed to resolve 'se.pathed.defa.client.GreetingService' via deferred binding
Scanning for additional dependencies: jar:file:/C:/eclipse/plugins/com.google.gwt.eclipse.sdkbundle.2.0.3_2.0.3.v201002191036/gwt-2.0.3/gwt-user.jar!/com/google/gwt/core/client/impl/SchedulerImpl.java
[WARN] The following resources will not be created because they were never committed (did you forget to call commit()?)
[WARN] C:\Users\Patrik\AppData\Local\Temp\gwtc301646733929273376.tmp\se.pathed.defa.DefaultGwtProject\compiler\se.pathed.defa.client.GreetingService.rpc.log
[WARN] For the following type(s), generated source was never committed (did you forget to call commit()?)
[WARN] se.pathed.defa.client.GreetingService_Proxy
[ERROR] Cannot proceed due to previous errors
答案 1 :(得分：1)
如果客户端软件包中的任何内容导入未列入白名单，则会发生这种情况。例如，我点击这个是因为我的autoimport将一个apache commons lang类导入到我的客户端代码中。
人们必须查看他们的导入，以确保客户端代码中没有任何奇怪的内容。
GWT项目的结构如下：
com.app.client com.app.server
你不能在客户端拥有任何不兼容GWT的东西。