文件保存树形结构数据

本文主要研究了一下如何把树形结构的数据保存到文件并读取出来。为了更形象说明用了一个界面程序显示，程序用了model/view框架。

数据类

DataItem 就是保存在树形结构的基本数据。其最重要的保存数据的函数是SerialzeData

class DataItem
{
public:

    DataItem(int id = 100,QString name = "root");
    ~DataItem();

    void SetRoot(DataItem *root);
    void SerialzeData(bool isSave,QDataStream &stream);
    void Clear();
    void Init();
    //protected:
    int GetID()
    {
        return ID;
    }

    QString GetName()
    {
        return Name;
    }

    void SetID(int id)
    {
        ID = id;
    }

    void SetName(QString name)
    {
        Name = name;
    }

    int  GetSize()
    {
        return dataVec.size();
    }

    void AddItem(DataItem *pItem);

    void DeleteItem(DataItem *pItem);

    void DeleteItem(int index);

    DataItem *GetItem(int index);

    DataItem *GetParent()
    {
        return pRoot;
    }

    int indexOf(DataItem* pItem);
private:
    int ID;
    QString Name;
    vector<DataItem*>  dataVec;
    DataItem *pRoot;
};

DataItem::DataItem( int id,QString name ):ID(id),Name(name),pRoot(NULL)
{
    //pRoot = new DataItem(100,"Root");
}

DataItem::~DataItem()
{

}
//SerialzeData 原来是，保存数据时，先保存每个项的数据，在后面保存该项的子节点个数，并递归保存各个子节点数据
void DataItem::SerialzeData( bool isSave,QDataStream &stream )
{
    if (isSave)
    {
        stream<<GetID()<<GetName();  //save ID and Name
        stream<<dataVec.size();     //save  the number of child
        for(int i = 0; i < dataVec.size(); ++i)
        {
            dataVec[i]->SerialzeData(isSave,stream);
        }
    }
    else
    {
        int id;
        int size;
        QString name;
        stream>>id>>name;  //Get ID and Name
        SetID(id);
        SetName(name);
        stream>>size;     //Get  the number of child
        for(int i = 0; i < size; ++i)
        {
            DataItem *pItem = new DataItem(0,"name");
            pItem->SerialzeData(isSave,stream);
            AddItem(pItem);
        }
    }
}

void DataItem::AddItem( DataItem *pItem )
{
    pItem->SetRoot(this);
    dataVec.push_back(pItem);
}

void DataItem::DeleteItem( DataItem *pItem )
{
    vector<DataItem*>::iterator it = dataVec.begin();
    for (it; it != dataVec.end(); ++it)
    {
        if (*it == pItem)
        {
            dataVec.erase(it);
            break;
        }
    }
}

void DataItem::DeleteItem( int index )
{
    if (index < dataVec.size())
    {
        vector<DataItem*>::iterator it = dataVec.begin();
        it = it + index;
        dataVec.erase(it);
    }
}

void DataItem::Init()
{
    for (int i = 0; i < 5; ++i)
    {
        DataItem *pItem = new DataItem(i,QString("child%1").arg(i));
        pRoot->AddItem(pItem);
        for (int j = 0; j < 2; ++j)
        {
            DataItem *pChild = new DataItem(j,QString("grandchild%0 -%1").arg(i).arg(j));
            pItem->AddItem(pChild);
        }
    }
}

void DataItem::SetRoot( DataItem *root )
{
    pRoot = root;
}

void DataItem::Clear()
{
    dataVec.clear();
}

DataItem * DataItem::GetItem( int index )
{
      if (index < dataVec.size())
        {
            return dataVec[index];
        }
        else
        {
            return NULL;
        }
}

int DataItem::indexOf( DataItem* pItem )
{
    int index = -1;
    for (int i = 0; i < dataVec.size(); ++i)
    {
        if (dataVec[i] == pItem)
        {
            index = i;
            break;
        }
    }
    return index;
}

数据模型

TreeDataModel的底层数据就是上面定义的DataItem。用这种视图/模型的编程方式可以尽量减少数据与界面的耦合性。由于继承了QAbstractItemModel。所以必须重写其中的五个纯虚函数columnCount （），data（），index （），parent （）和rowCount（）。

class TreeDataModel:public QAbstractItemModel
{
    Q_OBJECT
public:
    TreeDataModel(QObject *parent = NULL);
    ~TreeDataModel();

    void SetRoot(DataItem *pRoot)
    {
        m_pTreeData = pRoot;
    }
    QModelIndex parent ( const QModelIndex & index ) const;
     QVariant   data ( const QModelIndex & index, int role = Qt::DisplayRole ) const ;
     QVariant   headerData ( int section, Qt::Orientation orientation, int role = Qt::DisplayRole ) const;
     QModelIndex    index ( int row, int column, const QModelIndex & parent = QModelIndex() ) const;
     int    columnCount ( const QModelIndex & parent = QModelIndex() ) const;
     int    rowCount ( const QModelIndex & parent = QModelIndex() ) const;
     DataItem* dataFromIndex(const QModelIndex &index) const;

     void SaveData(QDataStream &out);
     void LoadData(QDataStream &in);
protected:
private:
    DataItem  *m_pTreeData;
};

TreeDataModel::TreeDataModel( QObject *parent /*= NULL*/ ):QAbstractItemModel(parent)
{
    m_pTreeData = NULL;
}

TreeDataModel::~TreeDataModel()
{

}

QVariant TreeDataModel::data( const QModelIndex & index, int role /*= Qt::DisplayRole */ ) const
{
    DataItem *pItem = dataFromIndex(index);
    if ((pItem)&&(role == Qt::DisplayRole))
    {
        switch (index.column())
        {
        case 0:
            return pItem->GetID();
        case 1:
            return pItem->GetName();
        }
    }
    return QVariant();

}

QVariant TreeDataModel::headerData( int section, Qt::Orientation orientation, int role /*= Qt::DisplayRole */ ) const
{
    if ((section <2) && (orientation == Qt::Horizontal)&& (role == Qt::DisplayRole))
    {
        switch (section)
        {
        case 0:
            return tr("编号");

        case 1:
            return tr("名称");
        default:
            return QVariant();
        }
    }
    else
    {
        return QVariant();
    }
}

QModelIndex TreeDataModel::index( int row, int column, const QModelIndex & parent /*= QModelIndex() */ ) const
{
    if (!m_pTreeData ||row < 0 || column < 0)
    {
        return QModelIndex();
    }
    else
    {
        DataItem *pItem = dataFromIndex(parent);
        if (pItem)
        {
            DataItem *pChild = pItem->GetItem(row);
            if (pChild)
            {
                return createIndex(row,column,pChild);
            }
        }
        return QModelIndex();
    }
}

int TreeDataModel::columnCount( const QModelIndex & parent /*= QModelIndex() */ ) const
{
    return 2;
}

int TreeDataModel::rowCount( const QModelIndex & parent /*= QModelIndex() */ ) const
{
    DataItem *pItem = dataFromIndex(parent);
    if (pItem)
    {
        return pItem->GetSize();
    }
    return 0;
}

DataItem* TreeDataModel::dataFromIndex( const QModelIndex &index ) const
{
    if (index.isValid())
    {
        return static_cast<DataItem*>(index.internalPointer());
    }
    else
    {
        return m_pTreeData;               //这里不要返回NULL
    }
}

QModelIndex TreeDataModel::parent( const QModelIndex & index ) const
{
    if (index.isValid())
    {
        DataItem *pItem = dataFromIndex(index);
        if (pItem)
        {
            DataItem *pParent = pItem->GetParent();
            if (pParent)
            {
                DataItem *pGrandParent = pParent->GetParent();
                if (pGrandParent)
                {
                    int row = pGrandParent->indexOf(pParent);
                    return createIndex(row,index.column(),pParent);
                }
            }
        }
    }
    return QModelIndex();
}

void TreeDataModel::SaveData( QDataStream &out )
{
    m_pTreeData->SerialzeData(true,out);
}

void TreeDataModel::LoadData( QDataStream &in )
{
    m_pTreeData->SerialzeData(false,in);
}

主框架类

这个类主要实现左边的树形把数据保存到文件中，然后在右边的树形结构加载显示出来。

class MainWidget:public QWidget
{
    Q_OBJECT
public:
    MainWidget(QWidget *patent = NULL);
    ~MainWidget();

protected slots:
    void leftSelectBtnSlot();
    void rightSelectBtnSlot();
    void saveBtnSlot();
    void loadBtnSlot();

private:
    QSplitter         *m_pSplitter;
    QTreeView         *m_pLeftTreeView;
    QTreeView         *m_pRightTreeView;
    QPushButton       *m_pLeftSaveBtn;
    QPushButton       *m_pRightLoadBtn;
    QPushButton       *m_pLeftSelectBtn;
    QPushButton       *m_pRightSelectBtn;
    QLineEdit         *m_pLeftLEdit;
    QLineEdit         *m_pRightLEdit;
    QGridLayout       *m_pLeftLayout;
    QGridLayout       *m_pRightLayout;

    TreeDataModel     *m_pLeftModel;
    TreeDataModel     *m_pRightModel;


};

MainWidget::MainWidget( QWidget *patent /*= NULL*/ ):QWidget(patent)
{
    m_pLeftModel = new TreeDataModel();
    m_pRightModel = new TreeDataModel();

    m_pSplitter = new QSplitter(this);
    QFrame *pLeftFrame = new QFrame(this);
    QFrame *pRightFrame = new QFrame(this);
    m_pLeftLayout = new QGridLayout(pLeftFrame);
    m_pRightLayout = new QGridLayout(pRightFrame);
    m_pLeftLEdit = new QLineEdit(this);
    m_pRightLEdit = new QLineEdit(this);
    m_pLeftSaveBtn = new QPushButton(tr("保存"),this);
    m_pRightLoadBtn = new QPushButton(tr("加载"),this);
    m_pLeftTreeView = new QTreeView(this);
    m_pRightTreeView = new QTreeView(this);
    m_pLeftSelectBtn = new QPushButton(tr("选择文件"),this);
    m_pRightSelectBtn = new QPushButton(tr("选择文件"),this);
    m_pRightLEdit->setReadOnly(true);


    m_pLeftLayout->addWidget(m_pLeftSelectBtn,0,0,1,1);
    m_pLeftLayout->addWidget(m_pLeftLEdit,0,1,1,1);
    m_pLeftLayout->addWidget(m_pLeftSaveBtn,0,2,1,1);
    m_pLeftLayout->addWidget(m_pLeftTreeView,1,0,3,3);

    m_pRightLayout->addWidget(m_pRightSelectBtn,0,0,1,1);
    m_pRightLayout->addWidget(m_pRightLEdit,0,1,1,1);
    m_pRightLayout->addWidget(m_pRightLoadBtn,0,2,1,1);
    m_pRightLayout->addWidget(m_pRightTreeView,1,0,3,3);

    m_pLeftTreeView->setModel(m_pLeftModel);
    m_pRightTreeView->setModel(m_pRightModel);
    DataItem *pTreeData = new DataItem();
    pTreeData->SetRoot(pTreeData);
    pTreeData->Init();

    m_pLeftModel->SetRoot(pTreeData);
    //m_pRightModel->SetRoot(pTreeData);

    m_pSplitter->addWidget(pLeftFrame);
    m_pSplitter->addWidget(pRightFrame);

    connect(m_pLeftSelectBtn,SIGNAL(clicked()),this,SLOT(leftSelectBtnSlot()));
    connect(m_pRightSelectBtn,SIGNAL(clicked()),this,SLOT(rightSelectBtnSlot()));
    connect(m_pLeftSaveBtn,SIGNAL(clicked()),this,SLOT(saveBtnSlot()));
    connect(m_pRightLoadBtn,SIGNAL(clicked()),this,SLOT(loadBtnSlot()));
    this->setFixedSize(QSize(650,250));
}

MainWidget::~MainWidget()
{

}

void MainWidget::leftSelectBtnSlot()     //这里只是选择了一个文件夹路径，在保存之前还需要加文件名
{
    QFileDialog Dialog(this,tr("选择目录"),"","");
    Dialog.setFileMode(QFileDialog::Directory);
    //Dialog.setNameFilter("*.data");
    if (Dialog.exec())
    {
        QStringList dirs = Dialog.selectedFiles();
        if (dirs.size() > 0)
        {
            m_pLeftLEdit->setText(QDir::toNativeSeparators(dirs.at(0)));
        }
    }
}

void MainWidget::rightSelectBtnSlot()      //选择之前保存的.data文件进行加载显示
{
    QFileDialog Dialog(this,tr("选择文件"),"","");
    Dialog.setFileMode(QFileDialog::ExistingFile);
    Dialog.setNameFilter("*.data");
    if (Dialog.exec())
    {
        QStringList files = Dialog.selectedFiles();
        if (files.size() > 0)
        {
            m_pRightLEdit->setText(QDir::toNativeSeparators(files.at(0)));
        }
    }
}

void MainWidget::saveBtnSlot()
{

    QString filePath = m_pLeftLEdit->text();
    if ((filePath.isEmpty()) || filePath.endsWith("\\") || filePath.endsWith("/"))   //必须得添加文件名，文件名规定后缀为.data
    {
        QMessageBox::information(this,tr("提示"),tr("请输入文件名"),QMessageBox::Ok);
        return;
    }
    else if(filePath.endsWith("data"))
    {
        QFile file(filePath);
        if (file.open(QIODevice::WriteOnly))
        {
            QDataStream outStream(&file);
            m_pLeftModel->SaveData(outStream);
        }
    }
}

void MainWidget::loadBtnSlot()
{
    QString filePath = m_pRightLEdit->text();
    if((!filePath.isEmpty()) &&filePath.endsWith("data"))
    {
        DataItem *pTreeData = new DataItem();
        //pTreeData->SetRoot(pTreeData);
        m_pRightModel->SetRoot(pTreeData);

        QFile file(filePath);
        if (file.open(QIODevice::ReadOnly))
        {
            QDataStream inStream(&file);
            m_pRightModel->LoadData(inStream);
            m_pRightTreeView->setModel(m_pRightModel);
            m_pRightTreeView->reset();                  //必须的，不然不会刷新
        }
    }
}

运行结果如下图

http://blog.csdn.net/hai200501019/article/details/11022581