hibernate中的通用<K,V>查询法

通过拼接HQL语句的形式实现，使用

StringBuilder

。

SELECT * FROM OBJ WHERE PARAM1 = 'VALUE1' AND PARAM2 = 'VALUE2' AND ....;

@Override
public List<T> queryByStringEqualMap(HashMap<String, Object> map)
throws Exception {
List<T> resultList = null;
try {
StringBuilder sql = new StringBuilder("SELECT o from "
+ getPersistentClass().getName() + " o WHERE ");
StringBuilder conStr = new StringBuilder("");
// 拼接条件
for (String key : map.keySet()) {
Object value = map.get(key);
conStr = conStr.append(String.format(" o.%s = :%s and", key,
key));
}
// 去掉最后一个and
sql.append(conStr.toString().substring(0, conStr.length() - 4));
Query query = em.createQuery(sql.toString());
for (String key : map.keySet()) {
query = query.setParameter(key, map.get(key));
}
resultList = query.getResultList();
} catch (Exception e) {
throw new SystemWifiException("查询数据库出错，请确认sql语句是否正确或者链接是否正确。"
+ e.getMessage());
}
if (resultList == null || (resultList != null && resultList.size() < 1)) {
return resultList;
// throw new BusinessWifiException("查询结果为空");
} else
return resultList;
}

SELECT * FROM OBJ WHERE PARAM1 IN ('VALUE1', 'VALUE2', .....);

@Override
public List<T> queryByStringInMap(HashMap<String, List<Object>> map)
throws Exception {
List<T> resultList = null;
try {
StringBuilder sql = new StringBuilder("SELECT o from "
+ getPersistentClass().getName() + " o WHERE ");
StringBuilder conStr = new StringBuilder("");
// 拼接条件
for (String key : map.keySet()) {
List<Object> value = map.get(key);
conStr = conStr.append(String.format(" o.%s in (:%s) and", key,
key));
}
// 去掉最后一个and
sql.append(conStr.toString().substring(0, conStr.length() - 4));
Query query = em.createQuery(sql.toString());
for (String key : map.keySet()) {
query = query.setParameter(key, map.get(key));
}
resultList = query.getResultList();
} catch (Exception e) {
throw new SystemWifiException(getPersistentClass().getName()+"查询数据库出错，请确认sql语句是否正确或者链接是否正确。");
}
if (resultList == null || (resultList != null && resultList.size() < 1)) {
// throw new BusinessWifiException("查询结果为空");
return resultList;
} else
return resultList;

}

实际使用

HashMap<String, Object> map = new HashMap<String, Object>();
map.put("key1", valueObj);
map.put("key2", valueObj);
List<Entity> results = entityDao.queryByStringEqualMap(map);

HashMap<String, List<Object>> map = new HashMap<String, List<Object>>();
List<Object> values = new ArrayList<Object>();
values.add(valueObj1);
values.add(valueObj2);
map.put("key1", values);
List<Entity> results = entityDao.queryByStringInMap(map);