#include "widget.h"
#include "ui_widget.h"
#include <QCursor>
#include <QDebug>
#include <QListView>
#include <QStringList>
#include <QStringListModel>
#include <QPoint>
#include <QMenu>
#include <QListWidgetItem>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new
 
 Ui::Widget)
{
    ui->setupUi(this);
    listview =new QListView(this);
    QStringList num;
    num<<"1"<<"2"<<"3"<<"4";
    QStringListModel *model=new QStringListModel(num);
    listview->setModel(model);
    listview->setContextMenuPolicy(Qt::CustomContextMenu);
    connect(listview, SIGNAL(customContextMenuRequested(const
 
 QPoint&)),
            this, SLOT(show_contextmenu1(const QPoint&)));
    //刪除測試
    //全部刪除
    //model->removeRows(0,model->rowCount());
    //刪除第幾個，一共刪除多少個
    //model->removeRows(0,3);
}

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

void Widget::show_contextmenu1(const QPoint& pos)
{
    // if(cmenu)//保證同時只存在一個menu，及時釋放記憶體
 

    // {
    // delete cmenu;
    // cmenu = NULL;
    // }
    qDebug()<<"show_contextmenu1";
    QMenu *cmenu = new QMenu(listview);
    QAction *ascendSortAction = cmenu->addAction("升序");
    QAction *descendSortAction = cmenu->addAction("降序");
    QAction *filterAction = cmenu->addAction("過濾");
    QAction *reshowAction = cmenu->addAction("過載");
    connect(ascendSortAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu1()));
    connect(descendSortAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu2()));
    connect(filterAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu3()));
    connect(reshowAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu4()));
    cmenu->exec(QCursor::pos());//在當前滑鼠位置顯示
    //cmenu->exec(pos)是在viewport顯示
}

上面程式碼右擊任何地方都會顯示選單，解決方法，增加一個if判斷，和清楚選中選項

//點選空白錯將不錯出現選單
    if(!((listview->selectionModel()->selectedIndexes()).empty()))
    {

        qDebug()<<"show_contextmenu1";
        QMenu *cmenu = new QMenu(listview);
        QAction *ascendSortAction = cmenu->addAction("升序");
        QAction *descendSortAction = cmenu->addAction("降序");
        QAction *filterAction = cmenu->addAction("過濾");
        QAction *reshowAction = cmenu->addAction("過載");
        connect(ascendSortAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu1()));
        connect(descendSortAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu2()));
        connect(filterAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu3()));
        connect(reshowAction, SIGNAL(triggered(bool)), this, SLOT(edit_menu4()));
        cmenu->exec(QCursor::pos());//在當前滑鼠位置顯示
        //cmenu->exec(pos)是在viewport顯示

        //把選中的清楚
        listview->selectionModel()->clear();
    }