org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:185) at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:135) at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:401) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1857) at com.fkr.po.HibernateSessionFactory.<clinit>(HibernateSessionFactory.java:34) at com.fkr.dao.UserDAO.add(UserDAO.java:14) at com.fkr.dao.UserDAO.main(UserDAO.java:11) Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer] at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:138) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:188) at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:403) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:520) at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:148) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:163) ... 6 more Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:135) ... 15 more Caused by: java.lang.NoClassDefFoundError: javassist/util/proxy/MethodFilter at org.hibernate.bytecode.internal.javassist.BytecodeProviderImpl.getProxyFactoryFactory(BytecodeProviderImpl.java:58) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactoryInternal(PojoEntityTuplizer.java:244) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:222) at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:212) at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:80) ... 20 more Caused by: java.lang.ClassNotFoundException: javassist.util.proxy.MethodFilter at java.net.URLClassLoader$1.run(URLClassLoader.java:366) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:425) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ... 25 more 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration configure INFO: HHH000043: Configuring from resource: /hibernate.cfg.xml 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration getConfigurationInputStream INFO: HHH000040: Configuration resource: /hibernate.cfg.xml 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration addResource INFO: HHH000221: Reading mappings from resource: com/fkr/po/User.hbm.xml 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration doConfigure INFO: HHH000041: Configured SessionFactory: null 二月 14, 2017 6:23:06 下午 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!) 二月 14, 2017 6:23:06 下午 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://127.0.0.1/h2?useUnicode=true&characterEncoding=UTF-8] 二月 14, 2017 6:23:06 下午 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000046: Connection properties: {user=root, password=****} 二月 14, 2017 6:23:06 下午 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000006: Autocommit mode: false 二月 14, 2017 6:23:06 下午 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000115: Hibernate connection pool size: 20 (min=1) 二月 14, 2017 6:23:06 下午 org.hibernate.dialect.Dialect <init> INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration$MappingsImpl addImport INFO: HHH000071: Duplicate import: com.fkr.po.User -> com.fkr.po.User 二月 14, 2017 6:23:06 下午 org.hibernate.cfg.Configuration$MappingsImpl addImport INFO: HHH000071: Duplicate import: com.fkr.po.User -> User %%%% Error Creating SessionFactory %%%% org.hibernate.InvalidMappingException: Could not parse mapping document from resource com/fkr/po/User.hbm.xml at org.hibernate.cfg.Configuration$MetadataSourceQueue.processHbmXml(Configuration.java:3762) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processHbmXmlQueue(Configuration.java:3751) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processMetadata(Configuration.java:3739) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1410) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1844) at com.fkr.po.HibernateSessionFactory.rebuildSessionFactory(HibernateSessionFactory.java:73) at com.fkr.po.HibernateSessionFactory.getSession(HibernateSessionFactory.java:55) at com.fkr.dao.UserDAO.add(UserDAO.java:14) at com.fkr.dao.UserDAO.main(UserDAO.java:11) Caused by: org.hibernate.DuplicateMappingException: Duplicate class/entity mapping com.fkr.po.User at org.hibernate.cfg.Configuration$MappingsImpl.addClass(Configuration.java:2835) at org.hibernate.cfg.HbmBinder.bindRoot(HbmBinder.java:178) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processHbmXml(Configuration.java:3759) ... 8 more Exception in thread "main" java.lang.NullPointerException at com.fkr.dao.UserDAO.add(UserDAO.java:27) at com.fkr.dao.UserDAO.main(UserDAO.java:11)
以上是错误信息，修改方法如下；
在你的项目的pom.xml中 <dependencies></dependencies>标签后面添加下面的配置信息内容即可解决上面的错误。
<repositories>
<repository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>maven</id>
<name>Maven Repository Switchboard</name>
<url>http://repo1.maven.org/maven2</url>
</repository>
</repositories>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.2</version>
<configuration>
<version>3.0</version>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>