分页方法getScrollDate

[code="java"]import java.beans.Introspector;

import java.beans.PropertyDescriptor;

import java.lang.reflect.Method;

import java.util.LinkedHashMap;



import javax.persistence.EmbeddedId;

import javax.persistence.Entity;

import javax.persistence.EntityManager;

import javax.persistence.PersistenceContext;

import javax.persistence.Query;



import org.springframework.transaction.annotation.Propagation;

import org.springframework.transaction.annotation.Transactional;



@Transactional

public abstract class DaoSupport implements DAO{

@PersistenceContext protected EntityManager em;



public void clear(){

em.clear();

}



public  void delete(Class entityClass,Object entityid) {

delete(entityClass, new Object[]{entityid});

}



public  void delete(Class entityClass,Object[] entityids) {

for(Object id : entityids){

em.remove(em.getReference(entityClass, id));

}

}

@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  T find(Class entityClass, Object entityId) {

return em.find(entityClass, entityId);

}



public void save(Object entity) {

em.persist(entity);

}



@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  long getCount(Class entityClass) {

return (Long)em.createQuery("select count("+ getCountField(entityClass) +") from "+ getEntityName(entityClass)+ " o").getSingleResult();

}



public void update(Object entity) {

em.merge(entity);

}



@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  QueryResult getScrollData(Class entityClass,

int firstindex, int maxresult, LinkedHashMap orderby) {

return getScrollData(entityClass,firstindex,maxresult,null,null,orderby);

}



@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  QueryResult getScrollData(Class entityClass,

int firstindex, int maxresult, String wherejpql, Object[] queryParams) {

return getScrollData(entityClass,firstindex,maxresult,wherejpql,queryParams,null);

}



@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  QueryResult getScrollData(Class entityClass, int firstindex, int maxresult) {

return getScrollData(entityClass,firstindex,maxresult,null,null,null);

}



@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  QueryResult getScrollData(Class entityClass) {

return getScrollData(entityClass, -1, -1);

}



@SuppressWarnings("unchecked")

@Transactional(readOnly=true,propagation=Propagation.NOT_SUPPORTED)

public  QueryResult getScrollData(Class entityClass, int firstindex, int maxresult

, String wherejpql, Object[] queryParams,LinkedHashMap orderby) {

QueryResult qr = new QueryResult();

String entityname = getEntityName(entityClass);

Query query = em.createQuery("select o from "+ entityname+ " o "+(wherejpql==null? "": "where "+ wherejpql)+ buildOrderby(orderby));

setQueryParams(query, queryParams);

if(firstindex!=-1 && maxresult!=-1) query.setFirstResult(firstindex).setMaxResults(maxresult);

qr.setResultlist(query.getResultList());

query = em.createQuery("select count("+ getCountField(entityClass)+ ") from "+ entityname+ " o "+(wherejpql==null? "": "where "+ wherejpql));

setQueryParams(query, queryParams);

qr.setTotalrecord((Long)query.getSingleResult());

return qr;

}



protected void setQueryParams(Query query, Object[] queryParams){

if(queryParams!=null && queryParams.length>0){

for(int i=0; i orderby){

StringBuffer orderbyql = new StringBuffer("");

if(orderby!=null && orderby.size()>0){

orderbyql.append(" order by ");

for(String key : orderby.keySet()){

orderbyql.append("o.").append(key).append(" ").append(orderby.get(key)).append(",");

}

orderbyql.deleteCharAt(orderbyql.length()-1);

}

return orderbyql.toString();

}

//获得实体名称

protected  String getEntityName(Class entityClass){

String entityname = entityClass.getSimpleName();

Entity entity = entityClass.getAnnotation(Entity.class);

if(entity.name()!=null && !"".equals(entity.name())){

entityname = entity.name();

}

return entityname;

}



protected  String getCountField(Class clazz){

String out = "o";

try {

PropertyDescriptor[] propertyDescriptors = Introspector.getBeanInfo(clazz).getPropertyDescriptors();

for(PropertyDescriptor propertydesc : propertyDescriptors){

Method method = propertydesc.getReadMethod();

if(method!=null && method.isAnnotationPresent(EmbeddedId.class)){

PropertyDescriptor[] ps = Introspector.getBeanInfo(propertydesc.getPropertyType()).getPropertyDescriptors();

out = "o."+ propertydesc.getName()+ "." + (!ps[1].getName().equals("class")? ps[1].getName(): ps[0].getName());

break;

}

}

} catch (Exception e) {

e.printStackTrace();

}

        return out;

}

}



QueryResult


[code="java"]public class QueryResult {
private List resultlist;
private long totalrecord;

public List getResultlist() {
return resultlist;
}
public void setResultlist(List resultlist) {
this.resultlist = resultlist;
}
public long getTotalrecord() {
return totalrecord;
}
public void setTotalrecord(long totalrecord) {
this.totalrecord = totalrecord;
}
}