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QT（4）信号、SLOT和QMap - Addressbook例子2

分类: 文章 • 2025-04-04 07:44:15

　　在之前的MeeGo开发者（五）：QT（3）对象和继承小例子基础上，我们增加三个button，参考http://doc.qt.nokia.com/latest/tutorials-addressbook-part2.html 、http://doc.qt.nokia.com/latest/tutorials-addressbook-part3.html和http://doc.qt.nokia.com/latest/tutorials-addressbook-part4.html，学习下面三个内容：

  1. 这三个button放置在layout上，然后摆放在GuidLayout。
  2. 当按这些button的时候，释放signal，这些信号将触发某些slot的函数。这是本次学习的重点。
  3. 学习QMap的使用方法。

QT（4）信号、SLOT和QMap - Addressbook例子2

　　最后的UI如图所示。我们在GuidLayou的（1,2）上摆放一个layout，layout上有三个button，按Add这进入增加新的联系人，按submit表示确定增加该联系人，按Cancel表示取消增加该联系人。在图的右边我们还看到一种三个button的摆放方式，我们会在程序中进行说明。

　　用户的信息存放在QMap中，QMap适合存放带索引的数据，在这个例子中，以name为索引，address为该人名对应的信息。QMap是不使用外置数据库的情况下存储数据库的很好的方式。

QT（4）信号、SLOT和QMap - Addressbook例子2

　　当button click后，释放一个signal，我们需要将这个signal和某个函数，在QT上称为slot函数。 在这个例子中，我们需要建立三个对应关心，如图所示。方式为：connect(addButton/*发出信号的对象*/, SIGNAL(clicked())/*捕抓的信号*/, this,SLOT(addContact())/*监测到信号后触发的slot函数*/);

　　main.cpp无需修改，addressbook.h如下所示：

#ifndef COM_WEI_ADDRESSBOOK_H
#define COM_WEI_ADDRESSBOOK_H

#include <QWidget>
#include <QMap>

class QLineEdit;
class QLabel;
class QTextEdit;
class QPushButton;

class AddressBook : public QWidget
{
Q_OBJECT

public:
AddressBook(QWidget * parent = NULL);

/* A slot is a function that responds to a particular signal. */
public slots:
void addContact();
void submitContact();
void cancel();

private:
QPushButton * addButton, * submitButton, * cancelButton;
QLineEdit * nameLine;
QTextEdit * addressText;

/* contacts用于存储联系人信息，是QMap对象，是存储key-value：这里联系人名字作为key，联系人地址作为value. */
QMap contacts;
QString oldName,oldAddress;
};

#endif

addressbook.cpp如下所示

/* addressbook.cpp - the implementation file for the AddressBook class */

#include <QtGuid>
#include "addressbook.h"

AddressBook :: AddressBook(QWidget * parent) : QWidget(parent)
{
QLabel * nameLabel = new QLabel(tr("Name:"));
nameLine = new QLineEdit();
nameLine->setReadOnly(true); // not editable

QLabel * addressLabel = new QLabel(tr("Address:"));
addressText = new QTextEdit();
addressText->setReadOnly(true);

addButton = new QPushButton("&Add");
addButton->show();
submitButton = new QPushButton("&Submit");
submitButton->hide();
cancelButton = new QPushButton("&Cancel");
cancelButton->hide();

QVBoxLayout * buttonLayout1 = new QVBoxLayout;
buttonLayout1->addWidget(addButton,Qt::AlignTop);
buttonLayout1->addWidget(submitButton);
buttonLayout1->addWidget(cancelButton);
buttonLayout1->addStretch(); //紧凑排列,否则按三等分布局，即上面UI图中的右图。

connect(addButton, SIGNAL(clicked()),this,SLOT(addContact()));
connect(submitButton, SIGNAL(clicked()),this,SLOT(submitContact()));
connect(cancelButton, SIGNAL(clicked()),this,SLOT(cancel()));

QGridLayout * mainLayout = new QGridLayout();
mainLayout->addWidget(nameLabel,0,0);
mainLayout->addWidget(nameLine,0,1);
mainLayout->addWidget(addressLabel,1,0,Qt::AlignTop);
mainLayout->addWidget(addressText,1,1);
mainLayout->addLayout(buttonLayout1,1,2);

setLayout(mainLayout);
setWindowTitle(tr("Simple Address Book"));
}

void AddressBook::addContact()
{
printf("Line %d: %s/n",__LINE__,__FUNCTION__);
oldName = nameLine->text();
oldAddress = addressText->toPlainText();

nameLine->clear();
addressText->clear();

nameLine->setReadOnly(false);
nameLine->setFocus(Qt::OtherFocusReason);
addressText->setReadOnly(false);

addButton->setEnabled(false);
submitButton->show();
cancelButton->show();
}

void AddressBook::submitContact()
{
printf("Line %d: %s/n",__LINE__,__FUNCTION__);
QString name = nameLine->text();
QString address = addressText->toPlainText();
if(name.isEmpty() || address.isEmpty()){
QMessageBox::information(this,tr("Empty Field"), tr("Please enter a name and address"));
return;
}

if(contacts.contains(name)){
QMessageBox::information(this,tr("Add Unsuccessful!"), tr("Sorry,/"%1/" is already in your address book").arg(name));
return;
}

contacts.insert(name, address); //QMap的用法
QMessageBox::information(this, tr("Add Successful!"),
tr("<%1,%2> has been added to your address book.").arg(name,address));//%1,%2表示arg中的参数顺序，图见下

nameLine -> setReadOnly(true);
addressText -> setReadOnly(true);
addButton -> setEnabled(true);
submitButton->hide();
cancelButton->hide();
}

void AddressBook::cancel()
{
printf("Line %d: %s/n",__LINE__,__FUNCTION__);
nameLine->setText(oldName);
nameLine->setReadOnly(true);
addressText->setText(oldAddress);
addressText->setReadOnly(true);

addButton->setEnabled(true);
submitButton->hide();
cancelButton->hide();
}

　　QMessageBox的截图如下

QT（4）信号、SLOT和QMap - Addressbook例子2

QT（4）信号、SLOT和QMap - Addressbook例子2

　　我们在这个基础上做进一步处理。我们增加一个两个button，用于向前查看或者向后查看，再次实践布局，并且学习一个QMap这个存储。QMap是的entry是<key,value>，key的排列具体是否安hash值不清楚，但是在试验中，我们可以看到如果我们一次读取QMap的元素，将是按顺序（字母大小顺序）进行读出。begin是第一个元素，但是end不是最后一个元素，end可能是NULL，因此end-1才是最后一个有效元素。QMap的元素iterator是可以简单进行++和--操作的。

　　数据的基础操作是增/删/改/查，我们增加删/改两个功能，其中submit和cancel按键通用，在不同的功能要求下各组建的editabled/disenditabled，enabled/disenable，show/hide的显示要求不一样，我们采用一个函数updateUI来统计进行处理，利用一个enum区分不同的模式。将UI独立与功能也是开发的原则之一。

　　对于addressbook.h，我们增加相关的button定义和SLOT函数。

... ...
class AddressBook : public QWidget
{
... ...
public:
... ...
enum Mode {NavigationMode,AddingMode, EditingMode};//设置枚举方式

public slots:
... ...
void next();
void previous();
void editContact();
void removeContact();

private:
... ...
QPushButton * nextButton, * previousButton;
QPushButton * editButton, * removeButton;
Mode currentMode;
void updateUI(Mode mode); //用于专门处理UI的函数
};
... ...

　　对于addressbook.cpp文件，我们修改如下，并让程序看起来更为优雅：

... ...
AddressBook :: AddressBook(QWidget * parent) : QWidget(parent)
{
... ...
editButton = new QPushButton(tr("&Edit"));
editButton->setEnabled(false);
removeButton = new QPushButton(tr("&Remove"));
removeButton->setEnabled(false);
... ...
buttonLayout1->addWidget(editButton); //将edit和remove两个button放置在sumbit和calcel前面
buttonLayout1->addWidget(removeButton);
buttonLayout1->addWidget(submitButton);
buttonLayout1->addWidget(cancelButton);
... ...
connect(editButton, SIGNAL(clicked()),this,SLOT(editContact()));
connect(removeButton, SIGNAL(clicked()),this,SLOT(removeContact()));
... ...
nextButton = new QPushButton(tr("&Next"));
nextButton->setEnabled(false);
previousButton = new QPushButton(tr("&Previous"));
previousButton->setEnabled(false);
connect(nextButton,SIGNAL(clicked()),this,SLOT(next()));
connect(previousButton,SIGNAL(clicked()),this,SLOT(previous()));
QHBoxLayout * buttonLayout2 = new QHBoxLayout;
buttonLayout2->addWidget(nextButton);
buttonLayout2->addWidget(previousButton);
... ...
mainLayout->addLayout(buttonLayout1,1,2);
mainLayout->addLayout(buttonLayout2,2,1);
... ...
}

void AddressBook::updateUI(Mode mode){
currentMode = mode;
switch(mode){
case AddingMode:
case EditingMode:
if(mode == AddingMode)
editButton->hide();
else if(mode == EditingMode)
addButton->hide();
removeButton->hide();

nameLine->setReadOnly(false);
nameLine->setFocus(Qt::OtherFocusReason);
addressText -> setReadOnly(false);

addButton->setEnabled(false);
editButton->setEnabled(false);
removeButton->setEnabled(false);
nextButton->setEnabled(false);
previousButton->setEnabled(false);

submitButton->show();
cancelButton->show();
break;
case NavigationMode: //浏览模式：任何功能完成后都进入浏览模式，如果有一个元素，则next和previous有效，并在此模式下可以进入功能操作
nameLine->setReadOnly(true);
addressText -> setReadOnly(true);
if(contacts.isEmpty()){
nameLine->clear();
addressText->clear();
}
addButton->setEnabled(true);
editButton->setEnabled(!contacts.isEmpty());
removeButton -> setEnabled(!contacts.isEmpty());
nextButton -> setEnabled(!contacts.isEmpty());
previousButton -> setEnabled(!contacts.isEmpty());
addButton->show();
editButton->show();
removeButton->show();
submitButton->hide();
cancelButton->hide();
break;
default:
break;
}
}

void AddressBook::addContact()
{
oldName = nameLine->text();
oldAddress = addressText->toPlainText();
nameLine->clear();
addressText->clear();
updateUI(AddingMode);
}

void AddressBook::editContact(){
oldName = nameLine->text();
oldAddress = addressText->toPlainText();
updateUI(EditingMode);
}

void AddressBook::removeContact(){
QString name = nameLine->text();
QString address = addressText->toPlainText();

if(contacts.contains(name)){
if(QMessageBox::question(this,tr("Confirm Remove"), tr("Are you sure you want to remove %1").arg(name),
QMessageBox ::Yes | QMessageBox :: No) == QMessageBox :: Yes){
previous();
contacts.remove(name);//QMap操作
if(contacts.isEmpty()){
nameLine->clear();
addressText->clear();
}
QMessageBox::information(this,tr("Remove successful!"),
tr("/"%1/" is already removed from your address book").arg(name));
}
}
updateUI(NavigationMode);
}

void AddressBook::submitContact()
{
QString name = nameLine->text();
QString address = addressText->toPlainText();

if(name.isEmpty() || address.isEmpty()){
QMessageBox::information(this,tr("Empty Field"),
tr("Please enter a name and address"));
return;
}

switch(currentMode){
case AddingMode:
if(contacts.contains(name)){
QMessageBox::information(this,tr("Add Unsuccessful!"), tr("Sorry,/"%1/" is already in your address book").arg(name));
return;
}else{
contacts.insert(name, address);//QMap的使用：增加
QMessageBox::information(this, tr("Add Successful!"), tr("<%1,%2> has been added.").arg(name,address));
}
break;
case EditingMode:
if(oldName != name){
if(!contacts.contains(name)){
QMessageBox::information(this, tr("Edit successful!"), tr("Sorry,<%1> has been edited.").arg(name));
contacts.remove(oldName);//QMap使用：删除
contacts.insert(name,address); //QMap的使用：增加
}else{
QMessageBox::information(this, tr("Edit Unsuccessful!"), tr("Sorry,<%1> already in your addressbook.").arg(name));
cancel();
}
} else if(oldAddress != address){
QMessageBox::information(this, tr("Edit successful!"), tr("Sorry,<%1> has been edited.").arg(name));
contacts[name] = address; //可以采用类似数组的方法对QMap[key]进行赋值
cancel();
}break;
default:
break;
}
updateUI(NavigationMode);
}

void AddressBook::cancel()
{
nameLine->setText(oldName);
addressText->setText(oldAddress);
updateUI(NavigationMode);
}

void AddressBook::next()
{
QString name = nameLine->text();
QMap<QString,QString>::iterator i = contacts.find(name); //QMap的查找和interator

i ++; //可通过i++，将元素移到下一个元素

if(i == contacts.end()) //由于最后一个元素为NULL，并不实际存在，需要设为第一个元素
i = contacts.begin();

nameLine->setText(i.key()); //获取key的值
addressText->setText(i.value()); //获取value的值
}

void AddressBook::previous()
{
QString name = nameLine->text();
QMap<QString,QString>::iterator i = contacts.find(name);

if(i == contacts.begin()){ //如果是第一元素，需要移为实际的最后一个元素，即end-1
i = contacts.end()-1;
}else{
i --;
}

nameLine->setText(i.key());
addressText->setText(i.value());
}

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