效果图：

        候补

特别说明：

        该文有很多新奇的用法，包括载入ui文件、连接信号和控件等等，有很多值得学习的地方

具体实现：

配置文件

#! [0]
QT += widgets uitoolsHEADERS = textfinder.h
SOURCES = textfinder.cpp main.cpp
RESOURCES = textfinder.qrc
#! [0]target.path = $$[QT_INSTALL_EXAMPLES]/uitools/textfinder
INSTALLS += target

main.cpp

#include "textfinder.h"
#include <QApplication>//! [0]
int main(int argc, char *argv[])
{QApplication app(argc, argv);TextFinder textFinder;textFinder.show();return app.exec();
}
//! [0]

textfinder.h  textfinder.cpp

#ifndef TEXTFINDER_H
#define TEXTFINDER_H#include <QWidget>QT_BEGIN_NAMESPACE
class QLineEdit;
class QPushButton;
class QTextEdit;
QT_END_NAMESPACE//! [0]
class TextFinder : public QWidget
{Q_OBJECTpublic:explicit TextFinder(QWidget *parent = nullptr);private slots:void on_findButton_clicked();private:QPushButton *ui_findButton;QTextEdit *ui_textEdit;QLineEdit *ui_lineEdit;
};
//! [0]#endif // TEXTFINDER_H/*********************************************************************/
#include "textfinder.h"
#include <QFile>
#include <QLineEdit>
#include <QMessageBox>
#include <QPushButton>
#include <QTextEdit>
#include <QTextStream>
#include <QUiLoader>
#include <QVBoxLayout>//! [4]
static QWidget *loadUiFile(QWidget *parent)
{QFile file(":/forms/textfinder.ui");file.open(QIODevice::ReadOnly);QUiLoader loader;return loader.load(&file, parent);
}
//! [4]//! [5]
static QString loadTextFile()
{QFile inputFile(":/forms/input.txt");inputFile.open(QIODevice::ReadOnly);QTextStream in(&inputFile);in.setCodec("UTF-8");return in.readAll();
}
//! [5]//! [0]
TextFinder::TextFinder(QWidget *parent): QWidget(parent)
{QWidget *formWidget = loadUiFile(this);//! [1]ui_findButton = findChild<QPushButton*>("findButton");ui_textEdit = findChild<QTextEdit*>("textEdit");ui_lineEdit = findChild<QLineEdit*>("lineEdit");
//! [0] //! [1]//! [2]QMetaObject::connectSlotsByName(this);
//! [2]//! [3a]ui_textEdit->setText(loadTextFile());
//! [3a]//! [3b]QVBoxLayout *layout = new QVBoxLayout;layout->addWidget(formWidget);setLayout(layout);
//! [3b]//! [3c]setWindowTitle(tr("Text Finder"));
}
//! [3c]//! [6] //! [7]
void TextFinder::on_findButton_clicked()
{QString searchString = ui_lineEdit->text();QTextDocument *document = ui_textEdit->document();bool found = false;// undo previous change (if any)document->undo();if (searchString.isEmpty()) {QMessageBox::information(this, tr("Empty Search Field"),tr("The search field is empty. ""Please enter a word and click Find."));} else {QTextCursor highlightCursor(document);QTextCursor cursor(document);cursor.beginEditBlock();
//! [6]QTextCharFormat plainFormat(highlightCursor.charFormat());QTextCharFormat colorFormat = plainFormat;colorFormat.setForeground(Qt::red);while (!highlightCursor.isNull() && !highlightCursor.atEnd()) {highlightCursor = document->find(searchString, highlightCursor,QTextDocument::FindWholeWords);if (!highlightCursor.isNull()) {found = true;highlightCursor.movePosition(QTextCursor::WordRight,QTextCursor::KeepAnchor);highlightCursor.mergeCharFormat(colorFormat);}}//! [8]cursor.endEditBlock();
//! [7] //! [9]if (found == false) {QMessageBox::information(this, tr("Word Not Found"),tr("Sorry, the word cannot be found."));}}
}
//! [8] //! [9]

textfinder.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0"><class>Form</class><widget class="QWidget" name="Form"><property name="geometry"><rect><x>0</x><y>0</y><width>378</width><height>158</height></rect></property><property name="windowTitle"><string>Find Text</string></property><layout class="QVBoxLayout"><property name="spacing"><number>6</number></property><property name="leftMargin"><number>9</number></property><property name="topMargin"><number>9</number></property><property name="rightMargin"><number>9</number></property><property name="bottomMargin"><number>9</number></property><item><layout class="QGridLayout"><property name="leftMargin"><number>0</number></property><property name="topMargin"><number>0</number></property><property name="rightMargin"><number>0</number></property><property name="bottomMargin"><number>0</number></property><property name="spacing"><number>6</number></property><item row="0" column="1"><widget class="QLineEdit" name="lineEdit"/></item><item row="0" column="0"><widget class="QLabel" name="searchLabel"><property name="text"><string>&amp;Keyword:</string></property><property name="buddy"><cstring>lineEdit</cstring></property></widget></item><item row="0" column="2"><widget class="QPushButton" name="findButton"><property name="text"><string>&amp;Find</string></property></widget></item></layout></item><item><widget class="QTextEdit" name="textEdit"/></item></layout></widget><resources/><connections><connection><sender>lineEdit</sender><signal>returnPressed()</signal><receiver>findButton</receiver><slot>animateClick()</slot><hints><hint type="sourcelabel"><x>261</x><y>17</y></hint><hint type="destinationlabel"><x>320</x><y>17</y></hint></hints></connection></connections>
</ui>