这两天写了个基于sqlite的学生管理系统，同时也复习了qt的一些知识，也加深了自己队sqlite用法的理解。
 
在此，总结下自己在写的时候复习到的知识。



一、  如何为treewidgetitem添加右键菜单

第一步：
// 设置右键编辑
   ui.TREEwidget->setContextMenuPolicy(Qt::CustomContextMenu);
 
第二步 ：
Connect 相关的信号和槽；
    connect(ui.TREEwidget,
SIGNAL(customContextMenuRequested(const
QPoint&)),this, 
       SLOT(OnlistContextMenu(const
QPoint&)));
 
第三步  设置右键菜单项；
 
int demo003::OnlistContextMenu(const
QPoint&pos)
{
 
    QMenu 
menu;
    menu.addAction(ui.action_upload);
    menu.addAction(ui.action_delete);
    QPoint 
pt_global =ui.TREEwidget->mapToGlobal(pos);
    menu.exec(pt_global);
 
    return0;
}
当然 这一切的前提是，你已经在qtdesigner里面添加好了相关的action，
并且每个action都有相关的槽函数；

首先connect一下到槽函数:

connect(ui->treeWidget,SIGNAL(itemChanged(QTreeWidgetItem*,int)),this,SLOT(treeItemChanged(QTreeWidgetItem*,int)));

treeItemChanged函数如下:

void KqDlgXzpjzbTree::treeItemChanged(QTreeWidgetItem *item, int column)
{
    QString itemText = item->text(0);
    if (item->checkState(0) == Qt::Checked)
    {
        QTreeWidgetItem *parent = item->parent();
        int cnt = item->childCount();
        if (cnt >0)
        {
            for (int i = 0;i < cnt;i++)
            {
                 item->child(i)->setCheckState(0,Qt::Checked);
            }
        }
        else
        {
            updateParentItem(item);
        }
    }
    else if (item->checkState(0) == Qt::Unchecked)
    {
        int cnt = item->childCount();
        if (cnt > 0)
        {
            for (int i = 0;i < cnt;i++)
            {
                item->child(i)->setCheckState(0,Qt::Unchecked);
            }
        }
        else
        {
            updateParentItem(item);
        }
    }
}

updateParentItem(item);函数如下:

void KqDlgXzpjzbTree::updateParentItem(QTreeWidgetItem *item)
{
    QTreeWidgetItem *parent = item->parent();
    if(parent == NULL)
    {
        return;
    }
    //选中的子节点个数
    int selectedCount = 0;
    int childCount = parent->childCount();
    for (int i = 0; i < childCount; i++)
    {
        QTreeWidgetItem *childItem = parent->child(i);
        if (childItem->checkState(0) == Qt::Checked)
        {
            selectedCount++;
        }
    }
    if (selectedCount <= 0)
    {
        //未选中状态
        parent->setCheckState(0, Qt::Unchecked);
    }
    else if (selectedCount > 0 && selectedCount < childCount)
    {
        //部分选中状态
        parent->setCheckState(0, Qt::PartiallyChecked);
    }
    else if (selectedCount == childCount)
    {
        //选中状态
        parent->setCheckState(0, Qt::Checked);
    }
}

 




 

{
    ui->setupUi(this);

    ui->treeWidget->setHeaderLabels(QStringList()<<"英雄姓名"<<"英雄介绍");  //添加头项
    QStringList l,m,f;     //相当于C++中  list<string> l
    l<<"力量";
    m<<"敏捷";
    f<<"防御";
    QTreeWidgetItem *LL= new QTreeWidgetItem(l);   //创建树项
    QTreeWidgetItem *MM= new QTreeWidgetItem(m);
    QTreeWidgetItem *FF= new QTreeWidgetItem(f);
    ui->treeWidget->addTopLevelItem(LL);//添加
    ui->treeWidget->addTopLevelItem(MM);
    ui->treeWidget->addTopLevelItem(FF);
    QStringList ll,mm,ff;
    ll<<"力量狗";
    mm<<"敏捷狗";
    ff<<"防御狗";
    QTreeWidgetItem *LLL= new QTreeWidgetItem(ll);
    QTreeWidgetItem *MMM= new QTreeWidgetItem(mm);
    QTreeWidgetItem *FFF= new QTreeWidgetItem(ff);
    LL->addChild(LLL);//添加子项
    MM->addChild(MMM);
    FF->addChild(FFF);
}


 

在窗体上放一个TreeWidget控件和四个PushButton加一个Horizontal Spacer

布局如图



给树添加元素节点的方法和实现

.h文件


    QTreeWidgetItem * AddTreeRoot(QString name,QString desc);
    QTreeWidgetItem * AddTreeNode(QTreeWidgetItem *parent,QString name,QString desc);
.cpp文件



QTreeWidgetItem * TreeViewView::AddTreeRoot(QString name,QString desc)
{
    QTreeWidgetItem * item=new QTreeWidgetItem(QStringList()<<name<<desc);
    ui->tv_Source->addTopLevelItem(item);
    return item;
}

QTreeWidgetItem * TreeViewView::AddTreeNode(QTreeWidgetItem *parent,QString name,QString desc)
{
    QTreeWidgetItem * item=new QTreeWidgetItem(QStringList()<<name<<desc);
    parent->addChild(item);
    return item;
}
在构造方法里添加元素设置树的列数和标题的名称
当然可以设置Header不显示，根据你的需求定



ui->tv_Source->setColumnCount(2);
    ui->tv_Source->setHeaderLabels(QStringList()<<"Name"<<"Description");
    //ui->tv_Source->setHeaderHidden(true);
    QTreeWidgetItem * beiJingItem = AddTreeRoot("bejing","city");
    AddTreeNode(beiJingItem,"haidian","HaiDian");
    AddTreeNode(beiJingItem,"chaoYang","chaoYang");
    AddTreeNode(beiJingItem,"fengTai","fengTai");
    QTreeWidgetItem * HeiBeiItem =AddTreeRoot("hebei","city");
    AddTreeNode(HeiBeiItem,"baoDing","baoDing");
    AddTreeNode(HeiBeiItem,"shiJiaZhuang","shiJiaZhuang");


添加事件相对来说比较简单

直接调用我的前边写的方法，因为TreeWidget一直是选中状态就加了一个

添加根节点的槽
void TreeViewView::on_btn_Add_clicked()
{
    QTreeWidgetItem * item= ui->tv_Source->currentItem();
    if(item!=Q_NULLPTR)
    {
        AddTreeNode(item,"new","new");
    }
    else
    {
        AddTreeRoot("new","new");
    }
}

void TreeViewView::on_btn_AddRoot_clicked()
{
    AddTreeRoot("new","new");
}
修改方法也很简单
void TreeViewView::on_btn_Modify_clicked()
{
    QTreeWidgetItem * currentItem = ui->tv_Source->currentItem();

    if(currentItem==Q_NULLPTR)
    {
        return;
    }
    for(int i=0;i<currentItem->columnCount();i++)
    {
        currentItem->setText(i,tr("Modify")+QString::number(i));
    }
}

删除槽就要考虑的多一点
要看它有没有父节点
void TreeViewView::on_btn_Del_clicked()
{
    QTreeWidgetItem * currentItem = ui->tv_Source->currentItem();

    if(currentItem==Q_NULLPTR)
    {
        return;
    }
    //如果没有父节点就直接删除
    if(currentItem->parent()==Q_NULLPTR)
    {
        delete ui->tv_Source->takeTopLevelItem(ui->tv_Source->currentIndex().row());
    }
    else
    {
        //如果有父节点就要用父节点的takeChild删除节点
        delete currentItem->parent()->takeChild(ui->tv_Source->currentIndex().row());
    }
}


看一下效果


完整代码
.h文件








#ifndef TREEVIEWVIEW_H
#define TREEVIEWVIEW_H

#include <QDialog>
#include<QString>
#include<QTreeWidgetItem>
namespace Ui {
class TreeViewView;
}

class TreeViewView : public QDialog
{
    Q_OBJECT

public:
    explicit TreeViewView(QWidget *parent = 0);
    ~TreeViewView();

private slots:
    void on_tv_Source_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous);

    void on_btn_Add_clicked();

    void on_btn_AddRoot_clicked();

    void on_btn_Del_clicked();

    void on_btn_Modify_clicked();

private:
    Ui::TreeViewView *ui;
    QTreeWidgetItem * AddTreeRoot(QString name,QString desc);
    QTreeWidgetItem * AddTreeNode(QTreeWidgetItem *parent,QString name,QString desc);
};

#endif // TREEVIEWVIEW_H
.cpp文件



#include "treeviewview.h"
#include "ui_treeviewview.h"
#include <QStringList>
TreeViewView::TreeViewView(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::TreeViewView)
{
    ui->setupUi(this);

    ui->tv_Source->setColumnCount(2);
    ui->tv_Source->setHeaderLabels(QStringList()<<"Name"<<"Description");
    //ui->tv_Source->setHeaderHidden(true);
    QTreeWidgetItem * beiJingItem = AddTreeRoot("bejing","city");
    AddTreeNode(beiJingItem,"haidian","HaiDian");
    AddTreeNode(beiJingItem,"chaoYang","chaoYang");
    AddTreeNode(beiJingItem,"fengTai","fengTai");
    QTreeWidgetItem * HeiBeiItem =AddTreeRoot("hebei","city");
    AddTreeNode(HeiBeiItem,"baoDing","baoDing");
    AddTreeNode(HeiBeiItem,"shiJiaZhuang","shiJiaZhuang");
}

TreeViewView::~TreeViewView()
{
    delete ui;
}

QTreeWidgetItem * TreeViewView::AddTreeRoot(QString name,QString desc)
{
    QTreeWidgetItem * item=new QTreeWidgetItem(QStringList()<<name<<desc);
    ui->tv_Source->addTopLevelItem(item);
    return item;
}

QTreeWidgetItem * TreeViewView::AddTreeNode(QTreeWidgetItem *parent,QString name,QString desc)
{
    QTreeWidgetItem * item=new QTreeWidgetItem(QStringList()<<name<<desc);
    parent->addChild(item);
    return item;
}

void TreeViewView::on_tv_Source_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous)
{
    if(current==Q_NULLPTR)return;
    if(previous!=Q_NULLPTR)
    {
        previous->setBackground(0,Qt::transparent);
        previous->setBackground(1,Qt::transparent);
        previous->setTextColor(0,Qt::black);
        previous->setTextColor(1,Qt::black);
    }
    current->setTextColor(0,Qt::blue);
    current->setTextColor(1,Qt::blue);
    current->setBackground(0,Qt::red);
    current->setBackground(1,Qt::red);
}

void TreeViewView::on_btn_Add_clicked()
{
    QTreeWidgetItem * item= ui->tv_Source->currentItem();
    if(item!=Q_NULLPTR)
    {
        AddTreeNode(item,"new","new");
    }
    else
    {
        AddTreeRoot("new","new");
    }
}

void TreeViewView::on_btn_AddRoot_clicked()
{
    AddTreeRoot("new","new");
}

void TreeViewView::on_btn_Del_clicked()
{
    QTreeWidgetItem * currentItem = ui->tv_Source->currentItem();

    if(currentItem==Q_NULLPTR)
    {
        return;
    }
    //如果没有父节点就直接删除
    if(currentItem->parent()==Q_NULLPTR)
    {
        delete ui->tv_Source->takeTopLevelItem(ui->tv_Source->currentIndex().row());
    }
    else
    {
        //如果有父节点就要用父节点的takeChild删除节点
        delete currentItem->parent()->takeChild(ui->tv_Source->currentIndex().row());
    }
}

void TreeViewView::on_btn_Modify_clicked()
{
    QTreeWidgetItem * currentItem = ui->tv_Source->currentItem();

    if(currentItem==Q_NULLPTR)
    {
        return;
    }
    for(int i=0;i<currentItem->columnCount();i++)
    {
        currentItem->setText(i,tr("Modify")+QString::number(i));
    }
}