多地多关联的增加，修改和删除
package com.score.test; import java.util.HashSet; import java.util.Properties; import javax.naming.InitialContext; import javax.naming.NamingException; import com.score.dao.CourseDAO; import com.score.dao.ScoreDAO; import com.score.dao.StudentDAO; import com.score.entity.Course; import com.score.entity.Score; import com.score.entity.Student; public class TestScore { /** * @param args * @throws NamingException */ public static void main(String[] args) throws NamingException { Properties props=new Properties(); props.setProperty("java.naming.factory.initial","org.jnp.interfaces.NamingContextFactory"); props.setProperty("java.naming.provider.url","localhost:1099"); props.setProperty("java.naming.factory.url.pkgs","org.jboss.naming"); InitialContext cxt=new InitialContext(props); try{ ScoreDAO sdao=(ScoreDAO)cxt.lookup("ScoreDAOBean/remote"); StudentDAO studao=(StudentDAO)cxt.lookup("StudentDAOBean/remote"); CourseDAO coudao=(CourseDAO)cxt.lookup("CourseDAOBean/remote"); Score s1=new Score(); Score s2=new Score(); Student stu1=studao.findStudentById(new Integer(1)); Course c1=coudao.findCourseById(new Integer(1)); Course c2=coudao.findCourseById(new Integer(2)); HashSet<Course> hs=new HashSet<Course>(); hs.add(c1); hs.add(c2); stu1.setCourses(hs); studao.updateStudent(stu1); s1.setCourse(c1); s1.setStudent(stu1); s1.setScore(99d); s2.setCourse(c2); s2.setStudent(stu1); s2.setScore(98d); sdao.addScore(s1); sdao.addScore(s2); }catch(Exception e){ e.printStackTrace(); } } }
由于没有设置级联增加，所有这里手工增加。
修改关联表：
try{
ScoreDAO scoredao=(ScoreDAO)cxt.lookup("ScoreDAOBean/remote");
List<Score> ls=scoredao.findScoreByStudentId(new Integer(1));
for(Score s:ls){
s.setScore(100);
scoredao.updateScore(s);
}
}catch(Exception e){
e.printStackTrace();
}
删除学生：
try{ ScoreDAO scoredao=(ScoreDAO)cxt.lookup("ScoreDAOBean/remote"); StudentDAO studao=(StudentDAO)cxt.lookup("StudentDAOBean/remote"); List<Score> ls=scoredao.findScoreByStudentId(new Integer(1)); for(Score s:ls){ //s.setScore(100); //scoredao.updateScore(s); Student stu=s.getStudent(); studao.deleteStudent(stu.getId()); s.setStudent(null); scoredao.updateScore(s); }
报错：
java.lang.reflect.UndeclaredThrowableException at $Proxy1.deleteStudent(Unknown Source) at com.score.test.TestDelete.main(TestDelete.java:33) Caused by: java.lang.ClassNotFoundException: javax.persistence.EntityExistsException at org.jboss.remoting.serialization.ClassLoaderUtility.loadClass(ClassLoaderUtility.java:82) at org.jboss.remoting.loading.RemotingClassLoader.loadClass(RemotingClassLoader.java:76) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at org.jboss.remoting.loading.ObjectInputStreamWithClassLoader.resolveClass(ObjectInputStreamWithClassLoader.java:174) at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at org.jboss.remoting.serialization.impl.java.JavaSerializationManager.receiveObjectVersion2_2(JavaSerializationManager.java:239) at org.jboss.remoting.serialization.impl.java.JavaSerializationManager.receiveObject(JavaSerializationManager.java:133) at org.jboss.remoting.marshal.serializable.SerializableUnMarshaller.read(SerializableUnMarshaller.java:120) at org.jboss.remoting.transport.socket.MicroSocketClientInvoker.versionedRead(MicroSocketClientInvoker.java:957) at org.jboss.remoting.transport.socket.MicroSocketClientInvoker.transport(MicroSocketClientInvoker.java:586) at org.jboss.remoting.MicroRemoteClientInvoker.invoke(MicroRemoteClientInvoker.java:122) at org.jboss.remoting.Client.invoke(Client.java:1634) at org.jboss.remoting.Client.invoke(Client.java:548) at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:62) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107) at $Proxy1.deleteStudent(Unknown Source) at com.score.test.TestDelete.main(TestDelete.java:33) at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:74) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:67) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:53) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:107) ... 2 more
删除的顺序不对，看JBOSS报错：
Caused by: java.sql.BatchUpdateException: Cannot delete or update a parent row: a foreign key constraint fails (`ejb3/tb_score`, CONSTRAINT `FKFACAA58158DBE5D8` FOREIGN KEY (`student_id`) REFERENCES `tb_student` (`id`)) at com.mysql.jdbc.PreparedStatement.executeBatchSerially(PreparedStatement.java:1213) at com.mysql.jdbc.PreparedStatement.executeBatch(PreparedStatement.java:912) at org.jboss.resource.adapter.jdbc.WrappedStatement.executeBatch(WrappedStatement.java:519) at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48) at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:246) ... 36 more
先删除关联表的记录后才能删除：
try{ ScoreDAO scoredao=(ScoreDAO)cxt.lookup("ScoreDAOBean/remote"); StudentDAO studao=(StudentDAO)cxt.lookup("StudentDAOBean/remote"); List<Score> ls=scoredao.findScoreByStudentId(new Integer(1)); for(Score s:ls){ //s.setScore(100); //scoredao.updateScore(s); scoredao.deleteScore(s.getId()); }
这里还不能删除student，因为他还跟course表有关联。
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若是级联删除，可以直接删除student的，若级联删除的是score，score这个关联表被删除了。
@OneToMany(mappedBy="student",cascade=CascadeType.REMOVE) public Set<Score> getScores() { return scores; } public void setScores(Set<Score> scores) { this.scores = scores; }
SQL输出：
delete from tb_score where id=? 23:35:22,343 INFO [STDOUT] Hibernate: delete from tb_score where id=? 23:35:22,343 INFO [STDOUT] Hibernate: delete from tb_student where id=?
但是怎么连student和course的关联表也删除了呢？----级联的意思：不仅删除自己，
也删除与自己关联的对象（关联表）---暂且这么理解，有待严格的验证。
这里由于student对course没有设置级联删除，否则连同course表的级联也没有了。。。