我正在开发一个简单的网络应用程序来存储＆amp;在eclipse环境中使用带有Hibernate的GWT RPC从数据库中检索数据。我面临的问题是当我在映射文件中使用时，它工作正常。但是当我使用时，它开始引发数据库连接错误。除连接错误外，它还会引发一些例外情况。
这是堆栈跟踪：
137 [btpool0-0] INFO org.hibernate.cfg.Environment - Hibernate 3.3.1.GA
241 [btpool0-0] INFO org.hibernate.cfg.Environment - hibernate.properties not found
363 [btpool0-0] INFO org.hibernate.cfg.Environment - Bytecode provider name : javassist
434 [btpool0-0] INFO org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling
702 [btpool0-0] INFO org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml
702 [btpool0-0] INFO org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml
3508 [btpool0-0] INFO org.hibernate.cfg.Configuration - Reading mappings from resource : user.hbm.xml
4658 [btpool0-0] INFO org.hibernate.cfg.HbmBinder - Mapping class: rpctest.shared.User -> users
4820 [btpool0-0] INFO org.hibernate.cfg.Configuration - Configured SessionFactory: null
5133 [btpool0-0] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!)
5133 [btpool0-0] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 1
5133 [btpool0-0] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false
5331 [btpool0-0] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/userdata
5331 [btpool0-0] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=root, password=****}
7405 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - RDBMS: MySQL, version: 5.5.16
7405 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.18 ( Revision: tonci.grgin@oracle.com-20110930151701-jfj14ddfq48ifkfq )
7467 [btpool0-0] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.MySQLDialect
7546 [btpool0-0] INFO org.hibernate.transaction.TransactionFactoryFactory - Using default transaction strategy (direct JDBC transactions)
7586 [btpool0-0] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
7586 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled
7587 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled
7587 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15
7587 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled
7590 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled
7590 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled
7590 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Maximum outer join fetch depth: 2
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled
7592 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
7637 [btpool0-0] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory
7638 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {}
7638 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled
7638 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled
7638 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled
7687 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge
7687 [btpool0-0] INFO org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge - Cache provider: org.hibernate.cache.NoCacheProvider
7687 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled
7687 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled
7758 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout
7773 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled
7773 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled
7773 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo
7773 [btpool0-0] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled
9024 [btpool0-0] INFO org.hibernate.impl.SessionFactoryImpl - building session factory
Initial SessionFactory creation failed.org.hibernate.MappingException: could not instantiate id generator [entity-name=rpctest.shared.User]
Starting Jetty on port 8888
[WARN] Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract rpctest.shared.User[] rpctest.client.RpctestService.getUser()' threw an unexpected exception: java.lang.ExceptionInInitializerError
at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:385)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:588)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: java.lang.ExceptionInInitializerError
at rpctest.server.HibernateUtil.buildSessionFactory(HibernateUtil.java:16)
at rpctest.server.HibernateUtil.<clinit>(HibernateUtil.java:7)
at rpctest.server.RpctestServiceImpl.getUser(RpctestServiceImpl.java:54)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
... 22 more
Caused by: org.hibernate.MappingException: could not instantiate id generator [entity-name=rpctest.shared.User]
at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:132)
at org.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:175)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:224)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1327)
at rpctest.server.HibernateUtil.buildSessionFactory(HibernateUtil.java:11)
... 29 more
Caused by: org.hibernate.MappingException: could not interpret id generator strategy: assign
at org.hibernate.id.IdentifierGeneratorFactory.getIdentifierGeneratorClass(IdentifierGeneratorFactory.java:151)
at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:124)
... 33 more
[ERROR] 500 - POST /rpctest/testService (127.0.0.1) 57 bytes
Request headers
Accept: */*
Accept-Language: en-gb
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)
Accept-Encoding: gzip, deflate
Host: 127.0.0.1:8888
Connection: Keep-Alive
Referer: http://127.0.0.1:8888/Rpctest.html?gwt.codesvr=127.0.0.1:9997
X-GWT-Permutation: HostedMode
X-GWT-Module-Base: http://127.0.0.1:8888/rpctest/
Content-Type: text/x-gwt-rpc; charset=utf-8
Content-Length: 118
Cache-Control: no-cache
Response headers
Content-Type: text/plain
这是 Hibernate POJO文件：
package rpctest.shared;
import java.io.Serializable;
public class User implements Serializable {
private Integer id;
private String firstName;
private String lastName;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
映射文件：
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="rpctest.shared.User" table="users" >
<id name="id" type="int" column="id" >
<generator class="assign"/>
</id>
<property name="firstName">
<column name="first_name" />
</property>
<property name="lastName">
<column name="last_name"/>
</property>
</class>
</hibernate-mapping>
cfg文件
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost/userdata</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<!-- Mapping files -->
<mapping resource="user.hbm.xml"/>
</session-factory>
</hibernate-configuration>
GWT服务IMPL文件：
package rpctest.server;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
//import com.hib.HibernateUtil;
import org.hibernate.Session;
import org.hibernate.Transaction;
import rpctest.shared.User;
import rpctest.client.RpctestService;
public class RpctestServiceImpl extends RemoteServiceServlet implements RpctestService {
public String addUser(String id, String name1, String name2)
throws IllegalArgumentException {
int userID = Integer.parseInt(id);
Transaction trns = null;
Session session = HibernateUtil.getSessionFactory().openSession();
try {
trns = session.beginTransaction();
User user = new User();
user.setId(userID);
user.setFirstName(name1);
user.setLastName(name2);
session.save(user);
session.getTransaction().commit();
} catch (RuntimeException e) {
if(trns != null){
trns.rollback();
}
e.printStackTrace();
} finally{
session.flush();
session.close();
}
return name1+name2; // to test flextable entris only
}
@Override
public User[] getUser()
{
List<User> getUser = null;
Transaction trns = null;
Session session = HibernateUtil.getSessionFactory().openSession();
try {
trns = session.beginTransaction();
getUser = session.createQuery("from User").list();
trns.commit();
} catch (RuntimeException e) {
if(trns != null){
trns.rollback();
}
e.printStackTrace();
} finally{
session.flush();
session.close();
}
return getUser.toArray(new User[getUser.size()]);
}
}
答案 0 :(得分：0)
<generator class="assign"/>需要像
<generator class="assigned"/>