java.lang.NullPointerException Hibernate与Ehcache一起使用 [英] java.lang.NullPointerException Hibernate used with Ehcache
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问题描述
我的hibernate.cfg.xml：
<？xml version ='1.0'encoding ='utf-8'？>
<！DOCTYPE hibernate-configuration PUBLIC
- // Hibernate / Hibernate配置DTD 3.0 // EN
http://www.hibernate.org/dtd/hibernate-configuration -3.0.dtd>
< hibernate-configuration>
< session-factory>
< property name =hibernate.connection.driver_class> com.microsoft.sqlserver.jdbc.SQLServerDriver< / property>
< property name =hibernate.connection.url> JDBC：SQLSERVER：//本地主机：1433;的databaseName = Stock_indices< /性>
< property name =hibernate.connection.username> xxx< / property>
< property name =hibernate.connection.password> xxx< / property>
< property name =hibernate.show_sql> true< / property>
< property name =hibernate.dialect> org.hibernate.dialect.SQLServerDialect< / property>
< property name =hibernate.hbm2ddl.auto>更新< / property>
< property name =hibernate.c3p0.min_size> 5< / property>
< property name =hibernate.c3p0.max_size> 20< / property>
< property name =hibernate.c3p0.timeout> 300< / property>
< property name =hibernate.c3p0.max_statements> 50< / property>
< property name =hibernate.c3p0.idle_test_period> 30< / property>
< property name =hibernate.cache.region.factory_class> org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory< / property>
< property name =net.sf.ehcache.configurationResourceName> ehcache-entity.xml< / property>
< mapping resource =mapping.xml/>
< / session-factory>
< / hibernate-configuration>
ehcache-entity.xml：
<？xml version =1.0encoding =UTF-8？>
< ehcache>
< cache name =stockdata.StockDatabaseConnectioneternal =false
maxElementsInMemory =5overflowToDisk =truediskPersistent =false
timeToIdleSeconds =0 timeToLiveSeconds =300
memoryStoreEvictionPolicy =LRU/>
< / ehcache>
mapping.xml
<？xml version =1.0？>
<！DOCTYPE hibernate-mapping PUBLIC
- // Hibernate / Hibernate映射DTD 3.0 // EN
http://hibernate.sourceforge.net/hibernate-mapping-3.0 .dtd>
< hibernate-mapping package =stockdata>
< class name =StockDatabaseConnectiontable =STOCKINDEX>
< cache usage =read-only/>
< composite-id name =CompositeIDConnection>
< key-property name =tickercolumn =TICKER/>
< key-property name =indexdatecolumn =INDEXDATE/>
< / composite-id>
< property name =openprice> < column name =OPENPRICE/> < /性>
< property name =closingprice> < column name =CLOSEPRICE/> < /性>
< property name =highestprice> < column name =HIGHPRICE/> < /性>
< property name =lowestprice> < column name =LOWPRICE/> < /性>
< property name =volume> < column name =VOLUME/> < /性>
< / class>
< / hibernate-mapping>
然而，我得到这个例外：
java.lang.NullPointerException在org.hibernate.cache.ehcache.internal.util.HibernateUtil.loadAndCorrectConfiguration（HibernateUtil.java:64）
在org.hibernate.cache.ehcache .SingletonEhCacheRegionFactory.start（SingletonEhCacheRegionFactory.java:91）
at org.hibernate.internal.SessionFactoryImpl。< init>（SessionFactoryImpl.java:281）
at org.hibernate.cfg.Configuration.buildSessionFactory（ Configuration.java:1741）
............
看来，休眠不能加载配置？我该如何解决这个问题？ （serlvet在没有使用Ehcache的情况下工作正常）。
我的servlet类：
package stockdataservlet;
import java.io.IOException;
import java.math.BigDecimal;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
导入org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import com.google.gson.Gson;
import com.microsoft.sqlserver.jdbc。*;
public class DataServlet扩展HttpServlet {
private static final long serialVersionUID = 1L;
public static SessionFactory sessionfactory = null;
public void init（）{
try {
Class.forName（com.microsoft.sqlserver.jdbc.SQLServerDriver）;
Configuration conf = new Configuration（）;
conf.configure（）;
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder（）。applySettings（conf.getProperties（））。buildServiceRegistry（）;
sessionfactory = conf.buildSessionFactory（serviceRegistry）;
catch（Exception e）{
e.printStackTrace（）;
保护无效doGet（HttpServletRequest请求，HttpServletResponse响应）{
Session session = null;
尝试{
session = sessionfactory.openSession（）;
Transaction transaction = session.beginTransaction（）;
Query query = session.createSQLQuery（SELECT * FROM STOCKINDEX WHERE TICKER =：index）.addScalar（CLOSEPRICE）;
query.setParameter（index，AAA）;
List list = query.list（）;
transaction.commit（）;
String json = new Gson（）。toJson（list）;
/*response.setContentType(\"application/json）;
response.setCharacterEncoding（UTF-8）;
response.getWriter（）。write（json）; * /
}
catch（Exception e）{
e.printStackTrace（）;
}
finally {
session.close（）;
}
}
}
解决方案
这就是好吧。
如果资源名为ehcache.xml并放置在类路径中，则不必为属性net.sf.ehcache.configurationResourceName显式指定值。如果您有多个缓存管理器，则可以选择此选项。
或者，您可以将所有资源文件从lib移动到像WEB-INF / resources这样的目录，以便它在类路径中更容易引用它。
Ehcache在类路径的顶层查找名为ehcache.xml的文件。如果它没有在类路径中查找ehcache-failsafe.xml。 ehcache-failsafe.xml打包在Ehcache jar中，应该始终找到。
I used Hibernate 4.1.2 with Ehcache 2.4.3 (shipped together with hibernate when donwloaded hibernate).
My hibernate.cfg.xml :
<?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>
<property name="hibernate.connection.driver_class"> com.microsoft.sqlserver.jdbc.SQLServerDriver </property>
<property name="hibernate.connection.url"> jdbc:sqlserver://localhost:1433;databaseName=Stock_indices</property>
<property name="hibernate.connection.username">xxx</property>
<property name="hibernate.connection.password">xxx</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">300</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.idle_test_period">30</property>
<property name="hibernate.cache.use_second_level_cache">true</property>
<property name="hibernate.cache.use_query_cache">true</property>
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory </property>
<property name="net.sf.ehcache.configurationResourceName">ehcache-entity.xml</property>
<mapping resource="mapping.xml"/>
</session-factory>
</hibernate-configuration>
ehcache-entity.xml :
<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
<cache name="stockdata.StockDatabaseConnection" eternal="false"
maxElementsInMemory="5" overflowToDisk="true" diskPersistent="false"
timeToIdleSeconds="0" timeToLiveSeconds="300"
memoryStoreEvictionPolicy="LRU" />
</ehcache>
mapping.xml
<?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 package="stockdata">
<class name="StockDatabaseConnection" table="STOCKINDEX">
<cache usage="read-only" />
<composite-id name="CompositeIDConnection">
<key-property name="ticker" column="TICKER"/>
<key-property name="indexdate" column="INDEXDATE"/>
</composite-id>
<property name="openprice"> <column name="OPENPRICE" /> </property>
<property name="closingprice"> <column name="CLOSEPRICE" /> </property>
<property name="highestprice"> <column name="HIGHPRICE" /> </property>
<property name="lowestprice"> <column name="LOWPRICE" /> </property>
<property name="volume"> <column name="VOLUME" /> </property>
</class>
</hibernate-mapping>
However, I got this exception :
java.lang.NullPointerException at org.hibernate.cache.ehcache.internal.util.HibernateUtil.loadAndCorrectConfiguration(HibernateUtil.java:64)
at org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory.start(SingletonEhCacheRegionFactory.java:91)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:281)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1741)
............
It seems that hibernate can not load configuration? How can I solve the problem? (The serlvet works fine without using Ehcache).
My servlet class :
package stockdataservlet;
import java.io.IOException;
import java.math.BigDecimal;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import com.google.gson.Gson;
import com.microsoft.sqlserver.jdbc.*;
public class DataServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public static SessionFactory sessionfactory = null;
public void init() {
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Configuration conf = new Configuration();
conf.configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(conf.getProperties()).buildServiceRegistry();
sessionfactory = conf.buildSessionFactory(serviceRegistry);
}
catch(Exception e){
e.printStackTrace();
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) {
Session session = null;
try{
session = sessionfactory.openSession();
Transaction transaction = session.beginTransaction();
Query query = session.createSQLQuery("SELECT * FROM STOCKINDEX WHERE TICKER = :index ").addScalar("CLOSEPRICE");
query.setParameter("index", "AAA");
List list = query.list();
transaction.commit();
String json = new Gson().toJson(list);
/*response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.getWriter().write(json);*/
}
catch(Exception e){
e.printStackTrace();
}
finally{
session.close();
}
}
}
解决方案
That's allright. You do not have to explicitly specify value for property "net.sf.ehcache.configurationResourceName" if the resource is named ehcache.xml and placed in a class path. You can chose this option when you have multiple cache managers.
Or you can just move all your resource files from lib to a directory like WEB-INF/resources so that it becomes easier to reference it under classpath.
Ehcache looks for a file called ehcache.xml in the top level of the classpath. Failing that it looks for ehcache-failsafe.xml in the classpath. ehcache-failsafe.xml is packaged in the Ehcache jar and should always be found.
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