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而 QueryHelper 则是在 dbutils 的基础上进行一级简单的封装，提供一些经常使用的数据库操作方法和对数据缓存的支持。
数据库连接的释放方法请看这里。
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package
my.db;import
java.io.Serializable;import
java.math.BigInteger;import
java.sql.*;import
java.util.*;import
my.cache.CacheManager;import
net.oschina.Configurations;import
org.apache.commons.dbutils.QueryRunner;import
org.apache.commons.dbutils.handlers.*;import
org.apache.commons.lang.ArrayUtils;/** *
数据库查询助手 *
@author Winter Lau<br> */@SuppressWarnings("unchecked")public
class
QueryHelper { private
final
static
QueryRunner _g_runner = new
QueryRunner(); private
final
static
ColumnListHandler _g_columnListHandler = new
ColumnListHandler(){ @Override protected
Object handleRow(ResultSet rs) throws
SQLException { Object
obj = super.handleRow(rs); if(obj
instanceof
BigInteger) return
((BigInteger)obj).longValue(); return
obj; } }; private
final
static
ScalarHandler _g_scaleHandler = new
ScalarHandler(){ @Override public
Object handle(ResultSet rs) throws
SQLException { Object
obj = super.handle(rs); if(obj
instanceof
BigInteger) return
((BigInteger)obj).longValue(); return
obj; }
}; private
final
static
List<Class<?>> PrimitiveClasses = new
ArrayList<Class<?>>(){{ add(Long.class); add(Integer.class); add(String.class); add(java.util.Date.class); add(java.sql.Date.class); add(java.sql.Timestamp.class); }}; private
final
static
boolean
_IsPrimitive(Class<?> cls) { return
cls.isPrimitive() || PrimitiveClasses.contains(cls) ; } /** *
获取数据库连接 *
@return */ public
static
Connection getConnection() { try{ return
Configurations.getConnection(); }catch(SQLException
e){ throw
new
DBException(e); } } /** *
读取某个对象 *
@param sql *
@param params *
@return */ @SuppressWarnings("rawtypes") public
static
<T> T read(Class<T> beanClass, String sql, Object...params) { try{ return
(T)_g_runner.query(getConnection(), sql, _IsPrimitive(beanClass)?_g_scaleHandler:new
BeanHandler(beanClass), params); }catch(SQLException
e){ throw
new
DBException(e); } } public
static
<T> T read_cache(Class<T> beanClass, String cache, Serializable key, String sql, Object...params) { T
obj = (T)CacheManager.get(cache, key); if(obj
== null){ obj
= read(beanClass, sql, params); CacheManager.set(cache,
key, (Serializable)obj); } return
obj; } /** *
对象查询 *
@param <T> *
@param beanClass *
@param sql *
@param params *
@return */ @SuppressWarnings("rawtypes") public
static
<T> List<T> query(Class<T> beanClass, String sql, Object...params) { try{ return
(List<T>)_g_runner.query(getConnection(), sql, _IsPrimitive(beanClass)?_g_columnListHandler:new
BeanListHandler(beanClass), params); }catch(SQLException
e){ throw
new
DBException(e); } } /** *
支持缓存的对象查询 *
@param <T> *
@param beanClass *
@param cache_region *
@param key *
@param sql *
@param params *
@return */ public
static
<T> List<T> query_cache(Class<T> beanClass, String cache_region, Serializable key, String sql, Object...params) {
List<T>
objs = (List<T>)CacheManager.get(cache_region, key); if(objs
== null){ objs
= query(beanClass, sql, params); CacheManager.set(cache_region,
key, (Serializable)objs); } return
objs; } /** *
分页查询 *
@param <T> *
@param beanClass *
@param sql *
@param page *
@param count *
@param params *
@return */ public
static
<T> List<T> query_slice(Class<T> beanClass, String sql, int
page, int
count, Object...params) { if(page
< 0
|| count < 0)
throw
new
IllegalArgumentException("Illegal
parameter of ‘page‘ or ‘count‘, Must be positive."); int
from = (page - 1)
* count; count
= (count > 0)
? return
query(beanClass, sql + "
LIMIT ?,?",
ArrayUtils.addAll(params, new
Integer[]{from,count})); } /** *
支持缓存的分页查询 *
@param <T> *
@param beanClass *
@param cache *
@param cache_key *
@param cache_obj_count *
@param sql *
@param page *
@param count *
@param params *
@return */ public
static
<T> List<T> query_slice_cache(Class<T> beanClass, String cache, Serializable cache_key,
int
cache_obj_count, String sql, int
page, int
count, Object...params) { List<T>
objs = (List<T>)CacheManager.get(cache, cache_key); if(objs
== null)
{ objs
= query_slice(beanClass, sql, 1,
cache_obj_count, params); CacheManager.set(cache,
cache_key, (Serializable)objs); } if(objs
== null
|| objs.size()==0) return
objs; int
from = (page - 1)
* count; if(from
< 0) return
null; if((from+count)
> cache_obj_count)//超出缓存的范围 return
query_slice(beanClass, sql, page, count, params); int
end = Math.min(from + count, objs.size()); if(from
>= end) return
null; return
objs.subList(from, end); } /** *
运行统计查询语句。语句的运行结果必须仅仅返回一个数值 *
@param sql *
@param params *
@return */ public
static
long
stat(String sql, Object...params) { try{ Number
num = (Number)_g_runner.query(getConnection(), sql, _g_scaleHandler, params); return
(num!=null)?num.longValue():-1; }catch(SQLException
e){ throw
new
DBException(e); } } /** *
运行统计查询语句。语句的运行结果必须仅仅返回一个数值 *
@param cache_region *
@param key *
@param sql *
@param params *
@return */ public
static
long
stat_cache(String cache_region, Serializable key, String sql, Object...params) { Number
value = (Number)CacheManager.get(cache_region, key); if(value
== null){ value
= stat(sql, params); CacheManager.set(cache_region,
key, value); } return
value.longValue(); } /** *
运行INSERT/UPDATE/DELETE语句 *
@param sql *
@param params *
@return */ public
static
int
update(String sql, Object...params) { try{ return
_g_runner.update(getConnection(), sql, params); }catch(SQLException
e){ throw
new
DBException(e); } } /** *
批量运行指定的SQL语句 *
@param sql *
@param params *
@return */ public
static
int[]
batch(String sql, Object[][] params) { try{ return
_g_runner.batch(getConnection(), sql, params); }catch(SQLException
e){ throw
new
DBException(e); } }} |
OSChina底层数据库操作的类(QueryHelper)源代码
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原文地址：http://www.cnblogs.com/lcchuguo/p/5056908.html
