带着这个疑问我看了hibernate reference，看到hibernate提供session.createSQLQuery接口，似乎可以满足我的要求，好！让我来试试看，于是有了下面的代码：
public ListgetPublicIndex(String startDate, String endDate) throws SQLException { StringBuffer sql = new StringBuffer(); sql.append("select a.id as id, a.money as deposit, b.money as loan, c.money as loanleave, a.tdate as tdate") .append(" FROM publicindex a inner join publicindex b") .append(" on a.tdate = b.tdate and a.flag = '1' and b.flag = '2'") .append(" inner join publicindex c") .append(" on a.tdate = c.tdate and c.flag = '3'") .append(" where (a.tflag = 2 or a.tflag = 3 or a.tflag = 7) and") .append(" (b.tflag = 2 or b.tflag = 3 or b.tflag = 7) and") .append(" (c.tflag = 2 or c.tflag = 3 or c.tflag = 7) and") .append(" a.tdate >= to_date(?, 'yyyy-mm-dd') and") .append(" a.tdate <= to_date(?, 'yyyy-mm-dd')") .append(" order by a.tdate"); Session session = dao.openSession(); return session.createSQLQuery(sql.toString()).addEntity(Private.class).setParameter(0, startDate).setParameter(1, endDate).list(); }
说明下：dao是公司前辈封装的一个简单框架，同时支持jdbc和hibernate，对于Private.class，仅仅是个bean，并没有写hibernate mapping，测试发现抛了下面的异常：
org.hibernate.MappingException: Unknown entity: com.cuishen.edwview.pojo.Private
于是我就mapping了一个简单的Entity，做了个简单的单表sql查询，如下：
public ListgetTechnicApp(String date) throws SQLException { String sql = "select * from technicappindex t where t.tdate = to_date(?, 'yyyy-mm-dd')"; Session session = dao.openSession(); return session.createSQLQuery(sql).addEntity(TechnicApp.class).setParameter(0, date).list(); }
说明下：将technicappindex表mapping为TechnicApp，测试通过了！看来hibernate的sql query还是不能完全脱离mapping
于是我修改了dao的代码，在jdbc返回结果集做封装的模块中加入了如下代码：
/**
* 反射POJO的setter方法，将记录中匹配的列值注入POJO，最后以List返回，
* 在不区分大小写的情况下记录中的列名（加上'set'前缀）必须和POJO中的公有setter方法名一致，
* 否则将不会被注入
* @param list 要返回的list
* @param pojoClassName String 要注入的POJO的包路径, e.g 'com.cuishen.pojo.Cat'
* @param rs ResultSet 待封装的原始结果集
*/
private static void setPOJO(List list, String pojoClassName, ResultSet rs) {
try {
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount(); // 查询的列数
Method [] methodsToInvoke = new Method[columnCount];
Class pojo = Class.forName(pojoClassName);
Method [] methods = pojo.getMethods();
for(int i = 0; i < columnCount; i++) {
for(int j = 0; j < methods.length; j++) {
String methodName = methods[j].getName();
if(methodName.equalsIgnoreCase("set" + metaData.getColumnName(i + 1))) {
methodsToInvoke[i] = methods[j];
log4j.debug(">>>>>> method name : " + methodsToInvoke[i].getName() + " para name : " + methodsToInvoke[i].getParameterTypes()[0].getName());
log4j.debug("======= >>>>>>> column name : " + metaData.getColumnName(i + 1) + " column type : " + metaData.getColumnClassName(i + 1));
break;
}
}
}
while(rs.next()) {
Object obj = pojo.newInstance();
for(int i = 0; i < columnCount; i++) {
methodsToInvoke[i].invoke(obj, new Object[]{castValue(rs.getObject(i + 1), methodsToInvoke[i].getParameterTypes()[0])});
}
list.add(obj);
}
} catch (InstantiationException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
} catch (IllegalAccessException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
} catch (SQLException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
} catch (IllegalArgumentException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
} catch (InvocationTargetException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
} catch (ClassNotFoundException e) {
e.printStackTrace();
log4j.error(e.getMessage(), e);
}
}
/**
* 类型强制转换
* @param source
* @param target
* @return
*/
private static Object castValue(Object source, Class target) {
if(source instanceof BigDecimal) {
if(target == Long.class) return new Long(((BigDecimal)source).longValue());
else if(target == Integer.class) return new Integer(((BigDecimal)source).intValue());
else if(target == Short.class) return new Short(((BigDecimal)source).shortValue());
else if(target == Double.class) return new Double(((BigDecimal)source).doubleValue());
else if(target == Float.class) return new Float(((BigDecimal)source).floatValue());
}
return source;
}
然后在dao里实现了新的接口：
/**
* jdbc sql查询，将记录注入POJO，结果集最终以list返回
* @param sql String sql语句
* @param params sql中的参数
* @param pojo String POJO的包路径
*/
List sqlQueryAsPOJO(String sql, Object[] params, String pojo) throws SQLException;
哈哈，现在做多表连接查询简单多啦！
public ListgetPublicIndex(String startDate, String endDate) throws SQLException { StringBuffer sql = new StringBuffer(); sql.append("select a.id as id, a.money as deposit, b.money as loan, c.money as loanleave, a.tdate as tdate") .append(" FROM publicindex a inner join publicindex b") .append(" on a.tdate = b.tdate and a.flag = '1' and b.flag = '2'") .append(" inner join publicindex c") .append(" on a.tdate = c.tdate and c.flag = '3'") .append(" where (a.tflag = 2 or a.tflag = 3 or a.tflag = 7) and") .append(" (b.tflag = 2 or b.tflag = 3 or b.tflag = 7) and") .append(" (c.tflag = 2 or c.tflag = 3 or c.tflag = 7) and") .append(" a.tdate >= to_date(?, 'yyyy-mm-dd') and") .append(" a.tdate <= to_date(?, 'yyyy-mm-dd')") .append(" order by a.tdate"); return dao.sqlQueryAsPOJO(sql.toString(), new String[]{startDate, endDate}, "com.cuishen.edwview.pojo.Private"); }
新加的代码是对jdbc的简单封装，并没有用到hibernate，代码还不够通用，以后还要改进。