SQLGrammarException:could not initialize a collection:
hibernate异常：org.hibernate.exception.SQLGrammarException: could not initialize a collection: could not initialize a collection: [com.net.sys.entity.Net_User.Net_Roles#1]
问题是这样的，我在做一个登陆模块，开始没有设置多对多关系的时候一切正常，可以正常登录，但是在.hbm.xml设置了many to many 关系之后，就会出现这个异常，奇怪的是控制台的执行语句为：Hibernate: select net_roles0_.user_id as user1_1_, net_roles0_.role_id as role2_1_, net_role1_.id as id2_0_, net_role1_.role_name as role2_2_0_ from Net_RoleToUser net_roles0_, Net_role net_role1_ where net_roles0_.role_id=net_role1_.id(+) and net_roles0_.user_id=? 亮点是（+）
下面贴出文件，按照entity ，action ，service ，dao 的顺序：
Net_User ----用户的实体类---很有可能是问题的出现所在
public class Net_User implements java.io.Serializable {
// Fields
private Integer id;
private String username;
private String password;
private Set Net_Roles = new HashSet(0);
// Constructors
/** default constructor */
public Net_User() {
}
/** full constructor */
public Net_User(String username, String password) {
this.username = username;
this.password = password;
this.Net_Roles=Net_Roles;
}
// Property accessors
public Set<Net_Role> getNet_Roles() {
return Net_Roles;
}
public void setNet_Roles(Set netRoles) {
Net_Roles = netRoles;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return this.username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return this.password;
}
public void setPassword(String password) {
this.password = password;
}
}
public class Net_Role implements java.io.Serializable {
// Fields
private Integer id;
private String roleName;
private Set<Net_User> Net_Users = new HashSet(0);
// Constructors
/** default constructor */
public Net_Role() {
}
/** full constructor */
public Net_Role(String roleName) {
this.roleName = roleName;
this.Net_Users=Net_Users;
}
// Property accessors
public Set<Net_User> getNet_Users() {
return Net_Users;
}
public void setNet_Users(Set<Net_User> netUsers) {
Net_Users = netUsers;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getRoleName() {
return this.roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
if(obj instanceof Net_Role){
Net_Role role2=(Net_Role)obj;
return id.equals(role2.getId());
}else{
return false;
}
}
@Override
public int hashCode() {
// TODO Auto-generated method stub
return id.hashCode();
}
}
<hibernate-mapping>
<class name="com.net.sys.entity.Net_User" table="Net_sysuser" >
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="identity"></generator>
</id>
<property name="username" type="java.lang.String">
<column name="username" length="100" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="100" />
</property>
<!--
<set name="Net_Roles" table="Net_RoleToUser" cascade="all" inverse="true" >
<key>
<column name="user_id" length="50" />
</key>
<many-to-many class="com.net.sys.entity.Net_Role" >
<column name="role_id" length="50" />
</many-to-many>
</set>
-->
<hibernate-mapping>
<class name="com.net.sys.entity.Net_Role" table="Net_role" >
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="identity"></generator>
</id>
<property name="roleName" type="java.lang.String">
<column name="role_name" length="50" />
</property>
<set name="Net_Users" inverse="true" table="Net_RoleToUser" cascade="all" >
<key>
<column name="role_id" length="50" />
</key>
<many-to-many class="com.net.sys.entity.Net_User" >
<column name="user_id" length="50" />
</many-to-many>
</set>
</class>
</hibernate-mapping>
public class LoginAction extends ActionSupport {
private String username;
private String password;
private Net_User_Service netUserService;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Net_User_Service getNetUserService() {
return netUserService;
}
public void setNetUserService(Net_User_Service netUserService) {
this.netUserService = netUserService;
}
public String execute() {
// System.out.println("bomm !");
Net_User netUser = netUserService.autheication(username, password);
// System.out.println(" ~");
if (netUser == null) {
return "fail";
}
ServletActionContext.getRequest().getSession().setAttribute("user", netUser);
Set<Net_Role> roleSet = netUser.getNet_Roles();
for (Net_Role netRole : roleSet) {
System.out.println(roleSet);
}
return "success";
}
}
package com.net.sys.service;
import java.util.List;
import com.net.sys.entity.Net_User;
import com.net.sys.dao.Net_User_Dao;;
public class Net_User_Service {
private Net_User_Dao netUserDao;
public void setNetUserDao(Net_User_Dao netUserDao) {
this.netUserDao = netUserDao;
}
public Net_User autheication(String username, String password) {
List<Net_User> userlist =netUserDao.findByUsername(username);
for (Net_User netUser : userlist) {
if (netUser.getPassword().equals(password)) {
return netUser;
}
}
return null;
}
}
/** full constructor */
public Net_User(String username, String password，XXXXX) {
this.username = username;
this.password = password;
this.Net_Roles=Net_Roles;
}
ServletActionContext.getRequest().getSession().setAttribute("user", netUser);
Set<Net_Role> roleSet = netUser.getNet_Roles();
System.out.println("good !");
// for (Net_Role netRole : roleSet) {
// System.out.println(roleSet);
//
//}
public class Net_Role_Dao extends HibernateDaoSupport{
private static final Log log = LogFactory.getLog(Net_Role_Dao.class);
// property constants
public static final String NAME = "name";
protected void initDao() {
// do nothing
}
public void save(Net_Role transientInstance) {
log.debug("saving Net_Role instance");
try {
getHibernateTemplate().save(transientInstance);
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
public void delete(Net_Role persistentInstance) {
log.debug("deleting Net_Role instance");
try {
getHibernateTemplate().delete(persistentInstance);
log.debug("delete successful");
} catch (RuntimeException re) {
log.error("delete failed", re);
throw re;
}
}
public Net_Role findById(java.lang.String id) {
log.debug("getting Net_Role instance with id: " + id);
try {
Net_Role instance = (Net_Role) getHibernateTemplate().get(
"com.net.sys.entity.Net_Role", id);
return instance;
} catch (RuntimeException re) {
log.error("get failed", re);
throw re;
}
}
public List findByExample(Net_Role instance) {
log.debug("finding Net_Role instance by example");
try {
List results = getHibernateTemplate().findByExample(instance);
log.debug("find by example successful, result size: "
+ results.size());
return results;
} catch (RuntimeException re) {
log.error("find by example failed", re);
throw re;
}
}
public List findByProperty(String propertyName, Object value) {
log.debug("finding Net_Role instance with property: " + propertyName
+ ", value: " + value);
try {
String queryString = "from Net_Role as model where model."
+ propertyName + " = ? " + " ";
return getHibernateTemplate().find(queryString, value);
} catch (RuntimeException re) {
log.error("find by property name failed", re);
throw re;
}
}
public List findByName(Object name) {
return findByProperty(NAME, name);
}
public List findAll() {
log.debug("finding all Net_Role instances");
try {
String queryString = "from Net_Role";
return getHibernateTemplate().find(queryString);
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
}
public Net_Role merge(Net_Role detachedInstance) {
log.debug("merging Net_Role instance");
try {
Net_Role result = (Net_Role) getHibernateTemplate().merge(
detachedInstance);
log.debug("merge successful");
return result;
} catch (RuntimeException re) {
log.error("merge failed", re);
throw re;
}
}
public void attachDirty(Net_Role instance) {
log.debug("attaching dirty Net_Role instance");
try {
getHibernateTemplate().saveOrUpdate(instance);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
public void attachClean(Net_Role instance) {
log.debug("attaching clean Net_Role instance");
try {
getHibernateTemplate().lock(instance, LockMode.NONE);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
public static Net_Role_Dao getFromApplicationContext(ApplicationContext ctx) {
return (Net_Role_Dao) ctx.getBean("Net_Role_Dao");
}
}
