Eclipse上使用Hibernate5.0及以上版本编写第一个HelloWorld程序

Question

       
        这个贴子是为了帮助初学者解决使用Eclipse并使用Hibernate5.0及以上版本（我用的是 hibernate-release-5.1.0-Final）创建第一个Hibernate HelloWorld程序时，junit4测试时出现各种问题。
未知实体类（- org.hibernate.MappingException: Unknown entity），
找不到cfg.xml包（org.hibernate.internal.util.config.ConfigurationException: Could not locate cfg.xml resource）
的解决办法。
 我的环境:
Eclipse Java EE IDE for Web Developers.Version: Mars.2 Release (4.5.2) 
jdk1.8.0_92
hibernate-release-5.1.0-Final
JBoss Tools 4.3.1 Final1、当爆出：未知实体类（- org.hibernate.MappingException: Unknown entity）错误时，原因是：
Hibernate5.0及以上版本，与4.x以往版本不同的，最关键的代码——获得SessionFactory的方式不同private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;// 5.0及以上版本——不用通过ServiceRegistry
Configuration configuration = new Configuration().configure();
sessionFactory = new Configuration().configure().buildSessionFactory();
session = sessionFactory.getCurrentSession();
transaction = session.beginTransaction();// 4.x版本——需要通过ServiceRegistry
Configuration configuration = new Configuration().configure();
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
sessionFactory = config.buildSessionFactory(serviceRegistry);
session = sessionFactory.getCurrentSession();
transaction = session.beginTransaction();
还有一个找不到类的原因： 在cfg.xml配置文件中<mapping class="" />映射没有配置正确
（1）、可以通过持久化类来配置
（2）、 可以通过.hbm.xml来配置（3）、当然你也可以两个都加上去
------------------------------------------------------------------------------------------————----------------------------2、当爆出：找不到cfg.xml包（org.hibernate.internal.util.config.ConfigurationException: Could not locate cfg.xml resource）错误时，原因是: cfg.xml文件放置的位置不对
你需要把.cfg.xml文件放在src中的一个Source Floder下如下图原因在于，sessionFactory = new Configuration().configure().buildSessionFactory(); 这一段代码中获取cfg.xml文件的默认位置就是在src目录下。.
（configure()中是可以填写一个URL参数的，但是我不会写，还有，我把cfg.xml文件直接放在src目录下，有的时候可以正常运行，有的时候又说找不到cfg.xml文件。希望高手来解决这个问题，感谢！。）
贴出我的HelloWorld程序所有代码Students
package config;
import java.io.Serializable;
import java.util.Date;import javax.persistence.Entity;
import javax.persistence.Id;
@Entity(name="Students")
public class Students implements Serializable{
private static final long serialVersionUID = 1L;
@Id
private int sid; // 学号
private String sname; // 姓名
private String gender; // 性别
private Date brithday; // 出生日期
private String address; // 住址

public Students(){} public Students(int sid, String sname, String gender, Date brithday, String address) {
super();
this.sid = sid;
this.sname = sname;
this.gender = gender;
this.brithday = brithday;
this.address = address;
} public int getSid() {
return sid;
} public void setSid(int sid) {
this.sid = sid;
} public String getSname() {
return sname;
} public void setSname(String sname) {
this.sname = sname;
} public String getGender() {
return gender;
} public void setGender(String gender) {
this.gender = gender;
} public Date getBrithday() {
return brithday;
} public void setBrithday(Date brithday) {
this.brithday = brithday;
} public String getAddress() {
return address;
} public void setAddress(String address) {
this.address = address;
} @Override
public String toString() {
return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", brithday=" + brithday
+ ", address=" + address + "]";
};


}
TestStudents
public class TestStudents { private SessionFactory sessionFactory;
private Session session;
private Transaction transaction; @Before
public void init() {

// 获得 session工厂
sessionFactory = new Configuration().configure().buildSessionFactory();
// 获得 session
session = sessionFactory.getCurrentSession();
// 开启事务
transaction = session.beginTransaction(); } @After
public void destory() {
transaction.commit(); // 提交事务 } @Test
public void testSaveStudents() {
// 生成学生对象
Students students = new Students(2, "黄蓉", "女", new Date(), "桃花岛");
System.out.println(students.getSname() + students.getGender() + students.getAddress());
session.save(students); // 保存对象进入数据库
}
}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.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password">xxxxxx</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.format_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">create</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.current_session_context_class">thread</property>
        
        <mapping class="config.Students"/>
        <mapping resource="config/Students.hbm.xml"/>
    </session-factory>
</hibernate-configuration>
Students.hbm.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">
<!-- Generated May 22, 2016 11:40:35 PM by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
    <class name="config.Students" table="STUDENTS">
        <id name="sid" type="int">
            <column name="SID" />
            <generator class="assigned" />
        </id>
        <property name="sname" type="java.lang.String">
            <column name="SNAME" />
        </property>
        <property name="gender" type="java.lang.String">
            <column name="GENDER" />
        </property>
        <property name="brithday" type="java.util.Date">
            <column name="BRITHDAY" />
        </property>
        <property name="address" type="java.lang.String">
            <column name="ADDRESS" />
        </property>
    </class>
</hibernate-mapping>
------------------------------------------------------------------------------------------------------------------------------------------------------------------------最后的最后，要特别感谢这几个网址中的朋友。正是看到了这些提问与回答，才解决了我这弄了整整两天的问题。
http://tieba.baidu.com/p/4350852805
http://stackoverflow.com/questions/32405031/hibernate-5-org-hibernate-mappingexception-unknown-entity
http://www.coderanch.com/t/215954/ORM/databases/hibernate-cfg-xml

Answer 1

为什么 我按楼主所写的 出现错误javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute statement
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:147)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:155)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:162)
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1441)
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:491)
at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3201)
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2411)
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:467)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:146)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:220)
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:68)
at TestStudents.destory(TestStudents.java:33)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:36)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.hibernate.exception.SQLGrammarException: could not execute statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:63)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:45)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3003)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3503)
at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:89)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:589)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:463)
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337)
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1435)
... 32 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'hibernate.students' doesn't exist
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.Util.getInstance(Util.java:381)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1030)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3515)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3447)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1951)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2101)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2554)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1761)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2046)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1964)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1949)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:205)
... 41 more