package com.dudu.moa.dao;
import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.Collection;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.orm.jpa.JpaCallback;
import org.springframework.orm.jpa.support.JpaDaoSupport;
import org.springframework.util.Assert;
/**
* 泛化DAO基类.
*
* 由MyEclipse自动逆向生成的DAO泛化而成.
* 用户可扩展此类,定制自己项目中的DAO基类.
*
* @param <T> DAO访问的entity类
* @param <PK> DAO访问的entity的主键类
*
* @see JpaDaoSupport
*
* @author calvin
*/
public class GenericJpaDao<T, Serializable extends PK> extends JpaDaoSupport {
protected final Log log = LogFactory.getLog(getClass());
protected Class<T> entityClass;
protected String className;
@SuppressWarnings("unchecked")
public GenericJpaDao() {
// 通过范型反射，取得在子类中定义的entityClass.
this.entityClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
className = entityClass.getSimpleName();
}
public void create(T entity) {
Assert.notNull(entity);
log.debug("saveing " + className + "instance");
getJpaTemplate().persist(entity);
logger.debug("save successful");
}
public T update(T entity) {
Assert.notNull(entity);
log.debug("updating " + className + " instance");
T result = getJpaTemplate().merge(entity);
logger.debug("update successful");
return result;
}
public void delete(T entity) {
Assert.notNull(entity);
log.debug("deleting " + className + " instance");
getJpaTemplate().remove(entity);
logger.debug("delete successful");
}
public void delete(final PK id) {
Assert.notNull(id);
log.debug("deleting " + className + " instance");
getJpaTemplate().remove(findById(id));
logger.debug("delete successful");
}
/**
* @return id对应的Entity.如果id不存在,返回Null.
*/
public T findById(final PK id) {
Assert.notNull(id);
log.debug("finding " + className + " instance with id: " + id);
return getJpaTemplate().find(entityClass, id);
}
/**
* 根据属性查找对象.
*
* @param propertyName 属性名
* @param value 属性值
* @param rowStartIdxAndCount 可选的分页参数.第一个参数为起始的记录,第二个参数为返回的对象数量.
*
* eg.
* <CODE>
* findByProperty("country","china"); //查找属性值country为china的对象，返回所有对象.
* findByProperty("country","china",0,10); //查找属性值country为china的对象，返回第1-10个符合的对象.
* </CODE>
*/
@SuppressWarnings("unchecked")
public List<T> findByProperty(final String propertyName, final Object value, final int... rowStartIdxAndCount) {
Assert.hasLength(propertyName);
log.info("finding " + className + " instance with property: " + propertyName + " , value: " + value);
final String queryString = "select model from " + className + " model where model." + propertyName + "= ?";
int rowStartIdx = 0;
int rowCount = 0;
if (rowStartIdxAndCount != null && rowStartIdxAndCount.length > 0) {
rowStartIdx = Math.max(0, rowStartIdxAndCount[0]);
if (rowStartIdxAndCount.length > 1)
rowCount = Math.max(0, rowStartIdxAndCount[1]);
}
return findPaged(queryString, rowStartIdx, rowCount, value);
}
/**
* 根据属性查找唯一对象.
*
* @return 唯一对象.如果不存在符合条件的结果,返回Null,如果有多个对象符合条件,抛出异常.
*
* @param propertyName 属性名
* @param value 属性值
*/
public T findUniqueByProperty(final String propertyName, final Object value) {
return uniqueResult(findByProperty(propertyName, value));
}
/**
* 获取全部对象.
*
* @param rowStartIdxAndCount 可选的分页参数.第一个参数为起始的记录,第二个参数为返回的对象数量.
*
* eg.
* <CODE>
* findAll(); //返回所有对象.
* findAll(0,10); //返回第1-10个对象.
* </CODE>
*/
@SuppressWarnings("unchecked")
public List<T> findAll(final int... rowStartIdxAndCount) {
log.info("finding all " + className + " instances");
final String queryString = "select model from " + className + " model";
int rowStartIdx = 0;
int rowCount = 0;
if (rowStartIdxAndCount != null && rowStartIdxAndCount.length > 0) {
rowStartIdx = Math.max(0, rowStartIdxAndCount[0]);
if (rowStartIdxAndCount.length > 1)
rowCount = Math.max(0, rowStartIdxAndCount[1]);
}
return findPaged(queryString, rowStartIdx, rowCount);
}
/**
* 直接使用查询语句查询.
*
* @param values 任意数量的参数.
*/
@SuppressWarnings("unchecked")
public List find(final String queryString, final Object... values) {
Assert.hasLength(queryString);
return getJpaTemplate().find(queryString, values);
}
/**
* 直接使用查询语句查询,带分页参数.
*
* @param rowStartIdx 起始的记录,如不想设定，可设为-1.
* @param rowCount 返回的记录数,如不想设定，可设为-1.
* @param values 任意数量的参数.
*/
@SuppressWarnings("unchecked")
public List findPaged(final String queryString, final int rowStartIdx, final int rowCount, final Object... values) {
return getJpaTemplate().executeFind(new JpaCallback() {
public Object doInJpa(EntityManager em) {
Query query = em.createQuery(queryString);
if (values != null)
for (int i = 0; i < values.length; i++)
query.setParameter(i + 1, values[i]);
if (rowStartIdx > 0)
query.setFirstResult(rowStartIdx);
if (rowCount > 0)
query.setMaxResults(rowCount);
return query.getResultList();
}
});
}
/**
* 直接使用查询语句查询,返回唯一对象
*
* @param values 任意数量的参数.
* @return 唯一对象.如果不存在符合条件的结果,返回NULL,如果有多个对象符合条件，抛出异常.
*/
@SuppressWarnings("unchecked")
public Object findUnique(final String queryString, final Object... values) {
Assert.hasLength(queryString);
return uniqueResult(getJpaTemplate().find(queryString, values));
}
/**
* 取得entity的class.
*/
public Class<T> getEntityClass() {
return entityClass;
}
/**
* 取出列表的第一个对象.
* 如果列表为空返回Null,如果有多于一个对象,抛出异常.
*/
private static <E> E uniqueResult(Collection<E> results) {
if (results == null || results.isEmpty())
return null;
if (results.size() > 1)
throw new IllegalArgumentException("the Collection size is larger than 1");
return results.iterator().next();
}
}
