通用的DAO查询，常见方法集合

import java.io.*;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.type.Type;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

public class GenericDao extends HibernateDaoSupport{
private ThreadLocal<Session> sessions = new ThreadLocal<Session>();
private ThreadLocal<Transaction> transactions = new ThreadLocal<Transaction>();
public synchronized Session getMySession(){
Session session = sessions.get();
if(session==null){
session = getSession();
transactions.set(session.beginTransaction());
sessions.set(session);
}else
if(!session.isOpen()){
session = getSession();
transactions.set(session.beginTransaction());
sessions.set(session);
}
return session;
}
public synchronized void commitMySession(){
Session session = sessions.get();
if(session!=null&&session.isOpen()){
transactions.get().commit();
session.close();
}
transactions.remove();
sessions.remove();
}
public synchronized void rollbackMySession(){
Session session = sessions.get();
if(session!=null&&session.isOpen()){
transactions.get().rollback();
session.close();
}
transactions.remove();
sessions.remove();
}
public <T> T get(Class<T> clazz, Serializable id){
return (T)getHibernateTemplate().get(clazz, id);
}
public <T> T load(Class<T> clazz, Serializable id){
return (T)getHibernateTemplate().load(clazz, id);
}
public <T> void save(T entity){
//        System.out.println("---->gdao.save("+entity.getClass().getName()+")----");
getHibernateTemplate().save(entity);
}
public <T> void update(T entity){
getHibernateTemplate().update(entity);
}
public <T> void delete(T entity){
getHibernateTemplate().delete(entity);
}

public int execUpdateSQL(String sql, Serializable...values){
Session sess = getMySession();
SQLQuery query = sess.createSQLQuery(sql);
if(values!=null&&values.length>0){
for(int i=0; i<values.length; i++){
query.setParameter(i, values[i]);
}
}
return query.executeUpdate();
}
public Long getFirstLong(String sql, final Serializable... values) throws Exception{
List<String> params = new ArrayList<String>(1);
List<Type> types = new ArrayList<Type>(1);
params.add("c"); types.add(Hibernate.INTEGER);
Object obj = findUnique(sql, params, types, values);
if(obj==null){
return -1L;
}
if(obj instanceof Object[]){
obj = ((Object[])obj)[0];
}
if(obj instanceof Number){
return ((Number)obj).longValue();
}
return -1L;
}
//    public Long getFirstLong(String sql,  List<String>params, List<Type>types) throws Exception{
//        Object[] obj = findUnique(sql, params, types);
//        if(obj==null||obj.length==0){
//            return -1L;
//        }
//        Object object = obj[0];
//        if(object instanceof Number){
//            return ((Number)object).longValue();
//        }
//        return -1L;
//    }
public List<?> find(String hql){
return getHibernateTemplate().find(hql);
}
//    public List<?> find(String hql, final Object...values){
//        logger.info(hql);
//        return getHibernateTemplate().find(hql, values);
//    }

public <T> List<T> findByPage(Class<T> clazz, final int start, final int limit, final String where, final Serializable... values){
String hql = "from " + clazz.getName() + " as e";
if(where!=null&&where.length()>0){
hql += " where " + where;
}
final String fHql = hql;
return getHibernateTemplate().executeFind(new HibernateCallback(){

public Object doInHibernate(Session session)
throws HibernateException, SQLException {
Query q = session.createQuery(fHql);
if(values!=null&&values.length>0){
for(int i=0; i<values.length; i++){
q.setParameter(i, values[i]);
}
}
q.setFirstResult(start).setMaxResults(limit);
return q.list();
}

});
}
public <T> List<T> find(Class<T> clazz, final String where, final Serializable... values){
String hql = "from " + clazz.getSimpleName()+" as e";
if(where!=null&&where.length()>0){
hql += " where " + where;
}
return getHibernateTemplate().find(hql, values);
}
public long getTotalCountByHql(Class<?> clazz, final String where, final Serializable... values) throws Exception {
String hql = "select count(*) from " + clazz.getSimpleName()+" as e";
if(where!=null&&where.length()>0){
hql += " where " + where;
}
List<Number> cs = getHibernateTemplate().find(hql, values);
if(cs!=null&&cs.size()>0){
Number n = cs.get(0);
return n.longValue();
}
return 0;
}
public long getTotalCount(Class<?> clazz, final String where, final Serializable... values) throws Exception {
String sql = "select count(1) as c from " + clazz.getSimpleName() + " e";
if(where!=null&&where.length()>0){
sql += " where " + where;
}
return getFirstLong(sql, values);
}

public long getTotalCount(String sql, final Serializable... values) throws Exception {
return getFirstLong(sql, values).longValue();
}
public Object[] findUnique(final String sql,  List<String>params, List<Type>types, final Serializable...values) {
Session sess = getMySession();
logger.debug("------findUnique.getSession()! sess="+sess.hashCode());
SQLQuery query = sess.createSQLQuery(sql);
for(int j=0; j<params.size(); j++){
query.addScalar(params.get(j), types.get(j));
}
if(values!=null&&values.length>0){
for(int i=0; i<values.length; i++){
query.setParameter(i, values[i]);
}
}
query.setMaxResults(1);
List<?> list = query.list();
if(list==null||list.size()==0){
return null;
}
Object obj = list.get(0);
if(obj==null){
return null;
}
logger.debug("obj.type="+obj.getClass().getName());
if(!obj.getClass().isArray()){//如果返回值不是数组，则要进行相关的处理
if(obj instanceof Number){
if(obj instanceof Long){
return new Long[]{(Long)(obj)};
}
if(obj instanceof Integer){
return new Long[]{new Long((Integer)obj)};
}
return new Number[]{(Number)obj};
}
return new Object[]{obj};
}
return (Object[])obj;
}
public List<Object[]> find(final String sql, List<String>params, List<Type>types, final Serializable... values) {
Session sess = getMySession();
logger.debug("------find.getSession()! sess="+sess.hashCode());
SQLQuery query = sess.createSQLQuery(sql);

for(int j=0; j<params.size(); j++){
query.addScalar(params.get(j), types.get(j));
}
if(values!=null&&values.length>0){
for(int i=0; i<values.length; i++){
query.setParameter(i, values[i]);
}
}
return query.list();
}
public long getNextId(String sequence) throws Exception{
String sql = "select "+sequence+".nextval as nextid from dual";

Session sess = getMySession();
logger.debug("------generateId.getSession()! sess="+sess.hashCode());
SQLQuery query = sess.createSQLQuery(sql);
query.addScalar("nextid", Hibernate.LONG);
List<?> list = query.list();
if(list==null||list.size()==0){
return -1L;
}
Object obj = list.get(0);
logger.debug("obj.type="+obj.getClass().getName());
if(obj instanceof Number){
return ((Number)obj).longValue();
}
return -1L;
}
public boolean exists(String sql, final Object...values) throws Exception{
Session sess = getMySession();
logger.debug("------exists.getSession()! sess="+sess.hashCode());
SQLQuery query = sess.createSQLQuery(sql);
for(int i=0; i<values.length; i++){
query.setParameter(i, values[i]);
}
List<?> list = query.list();
if(list==null||list.size()==0){
return false;
}
return true;
}

}