Hibernate有其独有的Dialect，对不同的数据库实现sql的分页。
用过MyBatis for Java，它可以拦截SQL语句，通过Interceptor对原始的sql语句进行修改，也就是可以实现自定义Dialect，实现与Hibernate相同效果的分页Dialect。
可是最近搞了个IBatisNet+Spring.Net的框架，IBatisNet是ibatis for Java版本转移过来的。
它没有MyBatis新版本所增加的功能，而IBatisNet自带的分页是通过IDataReader实现的逻辑分页，虽说在局域网环境上，对内存和带宽的影响不是很大，但个人习惯上还是看着很恶心。
上网找了很多天的资料，并没有发现有相当的资料，也似乎没有人这样做过(或许是做了没有共享出来)。
但无意中发现有代码是可以获取到运行时的sql语句的，于是把IBatisNet源码中的实现重新搬出来，修改了一下，算是也能实现Dialect的效果。
主要代码如下：
public static IList QueryPageList(ISqlMapper sqlMap, String statementName, Object parameter, int offset, int limit)
{
IMappedStatement statement = sqlMap.GetMappedStatement(statementName);
if(!sqlMap.IsSessionStarted)
{
sqlMap.OpenConnection();
}
RequestScope request = statement.Statement.Sql.GetRequestScope(statement, parameter, sqlMap.LocalSession);
request.PreparedStatement.PreparedSql = dialect.GetLimitString(request.PreparedStatement.PreparedSql, offset, limit);
statement.PreparedCommand.Create(request, sqlMap.LocalSession, statement.Statement, parameter);
return RunQueryForList(request, sqlMap.LocalSession, parameter, statement.Statement);
}
public static IList<T> QueryPageList<T>(ISqlMapper sqlMap, String statementName, Object parameter, int offset, int limit)
{
IMappedStatement statement = sqlMap.GetMappedStatement(statementName);
if(!sqlMap.IsSessionStarted)
{
sqlMap.OpenConnection();
}
RequestScope request = statement.Statement.Sql.GetRequestScope(statement, new Hashtable(), sqlMap.LocalSession);
request.PreparedStatement.PreparedSql = dialect.GetLimitString(request.PreparedStatement.PreparedSql, offset, limit);
statement.PreparedCommand.Create(request, sqlMap.LocalSession, statement.Statement, parameter);
return (List<T>)RunQueryForList<T>(request, sqlMap.LocalSession, parameter, statement.Statement);
}
private static IList RunQueryForList(RequestScope request, ISqlMapSession session, object parameterObject, IStatement _statement)
{
IList list = null;
using(IDbCommand command = request.IDbCommand)
{
list = (_statement.ListClass == null)? (new ArrayList()):(_statement.CreateInstanceOfListClass());
IDataReader reader = command.ExecuteReader();
try
{
while(reader.Read())
{
object obj = ResultStrategyFactory.Get(_statement).Process(request, ref reader, null);
if(obj != BaseStrategy.SKIP)
{
list.Add(obj);
}
}
}
catch
{
throw;
}
finally
{
reader.Close();
reader.Dispose();
}
ExecutePostSelect(request);
RetrieveOutputParameters(request, session, command, parameterObject);
}
return list;
}
private static IList<T> RunQueryForList<T>(RequestScope request, ISqlMapSession session, object parameterObject, IStatement _statement)
{
IList<T> list = new List<T>();
using(IDbCommand command = request.IDbCommand)
{
list = (_statement.ListClass == null) ? (new List<T>()) : (_statement.CreateInstanceOfGenericListClass<T>());
IDataReader reader = command.ExecuteReader();
try
{
while(reader.Read())
{
object obj = ResultStrategyFactory.Get(_statement).Process(request, ref reader, null);
if(obj != BaseStrategy.SKIP)
{
list.Add((T)obj);
}
}
}
catch
{
throw;
}
finally
{
reader.Close();
reader.Dispose();
}
ExecutePostSelect(request);
RetrieveOutputParameters(request, session, command, parameterObject);
}
return list;
}
private static void ExecutePostSelect(RequestScope request)
{
while(request.QueueSelect.Count > 0)
{
PostBindind postSelect = request.QueueSelect.Dequeue() as PostBindind;
PostSelectStrategyFactory.Get(postSelect.Method).Execute(postSelect, request);
}
}
private static void RetrieveOutputParameters(RequestScope request, ISqlMapSession session, IDbCommand command, object result)
{
if(request.ParameterMap != null)
{
int count = request.ParameterMap.PropertiesList.Count;
for(int i = 0; i < count; i++)
{
IBatisNet.DataMapper.Configuration.ParameterMapping.ParameterProperty mapping = request.ParameterMap.GetProperty(i);
if(mapping.Direction == ParameterDirection.Output ||
mapping.Direction == ParameterDirection.InputOutput)
{
string parameterName = string.Empty;
if(session.DataSource.DbProvider.UseParameterPrefixInParameter == false)
{
parameterName = mapping.ColumnName;
}
else
{
parameterName = session.DataSource.DbProvider.ParameterPrefix +
mapping.ColumnName;
}
if(mapping.TypeHandler == null) // Find the TypeHandler
{
lock(mapping)
{
if(mapping.TypeHandler == null)
{
Type propertyType = ObjectProbe.GetMemberTypeForGetter(result, mapping.PropertyName);
mapping.TypeHandler = request.DataExchangeFactory.TypeHandlerFactory.GetTypeHandler(propertyType);
}
}
}
// Fix IBATISNET-239
//"Normalize" System.DBNull parameters
IDataParameter dataParameter = (IDataParameter)command.Parameters[parameterName];
object dbValue = dataParameter.Value;
object value = null;
bool wasNull = (dbValue == DBNull.Value);
if(wasNull)
{
if(mapping.HasNullValue)
{
value = mapping.TypeHandler.ValueOf(mapping.GetAccessor.MemberType, mapping.NullValue);
}
else
{
value = mapping.TypeHandler.NullValue;
}
}
else
{
value = mapping.TypeHandler.GetDataBaseValue(dataParameter.Value, result.GetType());
}
request.IsRowDataFound = request.IsRowDataFound || (value != null);
request.ParameterMap.SetOutputParameter(ref result, mapping, value);
}
}
}
}其中的dialect.GetLimitString()，你们可以用接口的方式，定义针对不同数据库的分页sql，拼接为分页sql即可。
而ExecutePostSelect和RetrieveOutputParameters方法，则是从按源实现代码来调用的，因为无法调用其原始代码，所以自己重新实现了一部分。
最近有人说，这东西具体怎么用其实看不懂，或者直接获取例子中的svn吧，里面集成的是spring.net+ibatis.net
svn://svn.code.sf.net/p/dswork/code/DsWorkNet
项目中引用的dll位于：svn://svn.code.sf.net/p/dswork/code/LibNet
也有集成了基于.net framework 4.0的MVC4的demo
svn://svn.code.sf.net/p/dswork/code/DsDemo/DemoNet
这个项目的运行还需要同时运行web项目：svn://svn.code.sf.net/p/dswork/code/web
即同时运行两个项目，web和DemoNet，否则样式和js等会找不到路径，在IIS Express中配置一下即可，DemoNet中有说明文件
以上所有的项目，获取到本地路径后，建议全部置于同一目录下。否则自己更改dll的引用路径