坚钢不可夺其志 天地莫敢争其锋

最近在做QT和Win32SDK的项目，其中涉及到利用QT的方式访问ACCESS数据库.

QT利用一种类细于JAVA JDBC的方式呈现给用户一种极简单易用的访问数据库的方式。

好，下面我直接用代码说话。以下是3个星期前我写的一个类模板，专门用于访问ACCESS。在我的设计中这个类模板的每一个实例化对象专门用于访问一张表。
以下是头文件component.h

#ifndef COMPONENT_H
#define COMPONENT_H

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
#pragma once
#endif

#include <QApplication>
#include <QString>
#include <QVector>
#include <QSqlTableModel>
#include <QSqlRecord>

int const PRIMARYKEY_INVALID_VALUE = -1;

template <typename T>
class SqlTableObj : public T
{
public:
    SqlTableObj() {}
    explicit SqlTableObj(typename T::PrimaryKeyType const &primaryKeyValue);

    typedef SqlTableObj<T> this_type;
    typedef QVector<this_type> CollectionType;

    static CollectionType const collection(QString const &filter = QString(""));
    static void updateState(QString const &filter = QString(""),int *a = NULL );
    static void updateStateEx( QString const &filter = QString(""),int row = 0,int index = 0,int value =0 );
    int getSignals();

private:
    static void createTableModel(QString const &filter, QSqlTableModel &model);
};

template <typename T>
SqlTableObj<T>::SqlTableObj(typename T::PrimaryKeyType const &primaryKeyValue)
{
    if (T::primaryKeyInvalidValue() != primaryKeyValue)
 {
   QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
   QSqlTableModel model( 0, qdb );

        QString filter = T::primaryKeyName() + QString("=%1");
        createTableModel(filter.arg(primaryKeyValue), model);
/*
        if (1 == model.rowCount())
  {
            T::assign(model.record(0));
        }
*/
   T::assign(model.record(0));
    }
}

template <typename T> typename SqlTableObj<T>::CollectionType const
SqlTableObj<T>::collection(QString const &filter/* = QString("")*/)
{
 QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
    QSqlTableModel model( 0, qdb );
    createTableModel(filter, model);

    this_type tableObj;
    CollectionType result;

    for (int i = 0; i < model.rowCount(); ++i)
 {
        tableObj.assign(model.record(i));
        if (tableObj.valid())
  {
            result.push_back(tableObj);
       }
    }

    return result;
}

template <typename T>
void SqlTableObj<T>::updateState( QString const &filter,int *a = NULL )
{
 QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
 QSqlTableModel model( 0, qdb );
 createTableModel(filter, model);
/**/
 for (int i = 0; i < model.rowCount(); i++)
 {
  model.setData( model.index( i, 2 ), a[i] );//a[i]
 }

 model.submitAll();
 //
}
template <typename T>
void SqlTableObj<T>::updateStateEx( QString const &filter = QString(""),
           int index = 0,int value =0 )
{
 QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
 QSqlTableModel model( 0, qdb );
 createTableModel(filter, model);

 model.setData( model.index( index, 2 ), value );

 model.submitAll();
//// model.record(index).value("state")
}
template <typename T>
void SqlTableObj<T>::updateStateEEx( QString const &filter = QString(""),
         int row = 0,int index = 0,int value =0 )
{
 QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
 QSqlTableModel model( 0, qdb );
 createTableModel(filter, model);

 model.setData( model.index( row, index ), value );

 model.submitAll();
 //// model.record(index).value("state")
}
template <typename T>
int SqlTableObj<T>::getSignals()
{
 QSqlDatabase qdb = QSqlDatabase::database( T::connectionName(),true );
 QSqlTableModel model( 0, qdb );
 createTableModel("", model);
  
 model.setEditStrategy(QSqlTableModel::OnFieldChange);
 T::assign(model.record(0));

 return 0;
}
template <typename T>
void SqlTableObj<T>::createTableModel(QString const &filter, QSqlTableModel &model)
{
    model.setTable(T::internalTableName());
    model.setFilter(filter);
    model.select();
}

class ComponentTable
{
public:
    ComponentTable();

    bool valid() const { return m_id != PRIMARYKEY_INVALID_VALUE; }

    int id() const { return m_id; }

    QString const name() const { return m_name; }
    void setName(QString const &newName);

    QString const filePathName() const { return m_filePathName; }

    int minDistance() const { return m_minDistance; }
     int maxDistance() const { return m_maxDistance; }

    float direction_X() const { return m_direction_X; }
     float direction_Y() const { return m_direction_Y; }
      float direction_Z() const { return m_direction_Z; }

    int fId_1() const { return m_fId_1; }
     int fId_2() const { return m_fId_2; }
      int fId_3() const { return m_fId_3; }

    int categoryId() const { return m_categoryId; }

private:
    friend class SqlTableObj<ComponentTable>;

    typedef int PrimaryKeyType;
    static PrimaryKeyType const primaryKeyInvalidValue() { return PRIMARYKEY_INVALID_VALUE; }
////////////////////////////////////////////////////////////////////////////////
    static QString const connectionName()
 {
  return qApp->applicationDirPath() + "/Database/myhpss.mdb";
 }
    static QString const internalTableName()
 {
  return "component";
 }
    static QString const primaryKeyName() { return "ID"; }

    void assign(QSqlRecord const &record);

    int m_id;

    QString m_name;

    QString m_filePathName;

    int m_minDistance;
    int m_maxDistance;

    float m_direction_X;
    float m_direction_Y;
    float m_direction_Z;

    int m_fId_1;
    int m_fId_2;
    int m_fId_3;

    int m_categoryId;
};

typedef SqlTableObj<ComponentTable> Component;
typedef QVector<Component> ComponentArray;

#endif  //COMPONENT_H

以下是component.cpp文件
#include "component.h"

ComponentTable::ComponentTable()
{
    m_id = PRIMARYKEY_INVALID_VALUE;

    m_minDistance = -1;
    m_maxDistance = -1;

    m_direction_X = 0.0f;
    m_direction_Y = 0.0f;
    m_direction_Z = 0.0f;

    m_fId_1 = -1;
    m_fId_2 = -1;
    m_fId_3 = -1;

    m_categoryId = -1;
}

void ComponentTable::setName(QString const &newName)
{
    m_name = newName;
    //待续：将新值写入数据库
}

void ComponentTable::assign(QSqlRecord const &record)
{
    m_id = record.value("ID").toInt();

    m_name = record.value(QObject::tr("名称")).toString();

    m_filePathName = record.value("filePathName").toString();

    m_minDistance = record.value("minDistance").toInt();
    m_maxDistance = record.value("maxDistance").toInt();

    m_direction_X = static_cast<float>(record.value("direction_X").toDouble());
    m_direction_Y = static_cast<float>(record.value("direction_Y").toDouble());
    m_direction_Z = static_cast<float>(record.value("direction_Z").toDouble());

    m_fId_1 = record.value("fId_1").toInt();
    m_fId_2 = record.value("fId_2").toInt();
    m_fId_3 = record.value("fId_3").toInt();

    m_categoryId = record.value("categoryID").toInt();
}
那个ComponentTable类就是一个能部分说明问题的例子。
关于完整例程我将随后补上。