(一)：configuration.configure();（默认加载src下的hibernate.cfg.xml文件）
1 private static SessionFactory sessionFactory = null;
2
3 static{
4 Configuration configuration = new Configuration();
5 configuration.configure();
6 sessionFactory = configuration.buildSessionFactory();
7 }
如果使用了这种加载方法那么在hibernate.cfg.xml文件中就需要mapping XX.hbm.xml文件了
<session-factory>
<mapping resource="domain/Students.hbm.xml"/>
<mapping resource="domain/Techer.hbm.xml"/>
</session-factory>
（二）：使用的是configuration.addClass(class);方法
1 private static SessionFactory sessionFactory = null;
2
3 static {
4
5 Configuration configuration = new Configuration();
6 configuration.configure();
7
8 configuration.addClass(Techer.class);
9 configuration.addClass(Students.class);
10
11 sessionFactory = configuration.buildSessionFactory();
12 }
如果使用了这种那么在hibernate.cfg.xml文件中就不需要mapping了。
如果既使用了addClass方法也在cfg.xml文件中添加了mapping就会如下错误：
1 java.lang.ExceptionInInitializerError
2 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
3 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
4 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
5 at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
6 at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:209)
7 at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:258)
8 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
9 at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:255)
10 at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
11 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
12 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
13 at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
14 at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
15 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
16 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
17 at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
18 at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
19 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
20 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
21 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
22 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
23 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
24 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
25 Caused by: org.hibernate.InvalidMappingException: Could not parse mapping document from resource domain/Techer.hbm.xml
26 at org.hibernate.cfg.Configuration.addResource(Configuration.java:641)
27 at org.hibernate.cfg.Configuration.addClass(Configuration.java:688)
28 at dao.App.<clinit>(App.java:17)
29 ... 23 more
30 Caused by: org.hibernate.DuplicateMappingException: Duplicate class/entity mapping domain.Techer
31 at org.hibernate.cfg.Configuration$MappingsImpl.addClass(Configuration.java:2407)
32 at org.hibernate.cfg.HbmBinder.bindRoot(HbmBinder.java:173)
33 at org.hibernate.cfg.Configuration.add(Configuration.java:771)
34 at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:606)
35 at org.hibernate.cfg.Configuration.addResource(Configuration.java:638)
36 ... 25 more