<分区>
对数据库进行如下查询:
Session session = EmployeesDAO.getSessionFactory().getCurrentSession();
List<Employee> employees = new ArrayList<Employee>();
try {
session.beginTransaction();
String hqlQuery = "from Employee emp "
+ "left join fetch emp.employeesOffices employeesOffice "
+ "left join fetch employeesOffice.office employeesOfficeOffice "
+ "left join fetch employeesOfficeOffice.company "
+ "left join fetch emp.address empAddress "
+ "left join fetch empAddress.city empAddressCity "
+ "left join fetch empAddressCity.country";
Query empQuery = session.createQuery(hqlQuery);
empQuery.setMaxResults(maxResult);
employees = (List<Employee>) empQuery.list();
session.getTransaction().commit();
} catch (HibernateException e) {
session.getTransaction().rollback();
e.printStackTrace();
}
在获取 employee.address.street、employee.address.houseNumber 或 employee.address.city 时失败，但出现异常:
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:164)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:285)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)
at com.employees.model.Address_$$_javassist_6.getCity(Address_$$_javassist_6.java)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:87)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:985)
at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fout_005f3(listEmployees_jsp.java:306)
at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fforEach_005f1(listEmployees_jsp.java:248)
at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fforEach_005f0(listEmployees_jsp.java:155)
at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspService(listEmployees_jsp.java:89)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:690)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:477)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329)
at com.employees.controller.EmployeeController.processRequest(EmployeeController.java:69)
at com.employees.controller.EmployeeController.doGet(EmployeeController.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
员工映射:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.employees.model.Employee" table="employees">
<id column="employee_id" name="employeeId" type="int">
<generator class="sequence">
<param name="sequence">EMP_SEQ</param>
</generator>
</id>
<property column="first_name" name="firstName" type="java.lang.String" />
<property column="last_name" name="lastName" type="java.lang.String" />
<many-to-one name="address" column="address_id"
class="com.employees.model.Address"/>
<set name="employeesOffices" >
<key column="employee_id" />
<one-to-many class="com.employees.model.EmployeeOffice"/>
</set>
</class>
</hibernate-mapping>
地址映射:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.employees.model.Address" table="addresses">
<id column="address_id" name="addressId" type="int">
<generator class="sequence">
<param name="sequence">ADDRESS_SEQ</param>
</generator>
</id>
<property column="street" name="street" type="java.lang.String" />
<property column="house_number" name="houseNumber" type="int" />
<many-to-one name="city" column="city_id"
class="com.employees.model.City"/>
</class>
</hibernate-mapping>
其他类(办公室、公司等)绝对正常。如果注释在 jsp 应用程序中加载地址字段的行没有任何异常。怎么了？顺便说一句，尽管有异常，它仍显示有关 jsp 的所有信息。