效果：

        导入一个文本文件到textEdit中，对指定的key关键字标红处理或者对关键字所在的行进行整行标红处理

实现：       

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();private slots:void on_selectBtn_clicked();//void on_setBtn_clicked();private:void defaultConfig();void loadStyleSheet(const QString &style);void filterKeyWord(const QString& key, const QString& color);private:Ui::Widget *ui;QString mAppPath;
};
#endif // WIDGET_Hcpp      //#include "widget.h"
#include "ui_widget.h"#include <QDebug>
#include <QDir>
#include <QFile>
#include <QStyle>
#include <QSettings>
#include <QTextStream>
#include <QFileDialog>
#include <QMessageBox>
#include <QTextDocument>Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);defaultConfig();loadStyleSheet(":/home.qss");
}Widget::~Widget()
{delete ui;
}void Widget::loadStyleSheet(const QString &style)
{if(style.isEmpty())return;QFile file(style);if(!file.open(QFile::ReadOnly))return;this->style()->unpolish(this);setStyleSheet(file.readAll());this->style()->polish(this);
}void Widget::on_selectBtn_clicked()
{QSettings config(mAppPath+"/setting.ini", QSettings::NativeFormat);auto lastPath = config.value("last_path", QDir::homePath()).toString();auto file = QFileDialog::getOpenFileName(this, tr("OpenFile"), lastPath,tr("Text(*.txt);; All file(*.*)"));if(file.isEmpty())return;QFile inputFile(file);inputFile.open(QIODevice::ReadOnly);QTextStream in(&inputFile);in.setCodec("UTF-8");ui->textEdit->setText(in.readAll());inputFile.close();config.setValue("last_path", file);ui->path->setText(file);//ui->textEdit->document()->undo();config.beginGroup("keys");auto kk = config.childKeys();foreach (auto key, config.childKeys())filterKeyWord(key, config.value(key, "#000").toString());config.endGroup();
}void Widget::defaultConfig()
{mAppPath = QApplication::applicationDirPath();QSettings config(mAppPath+"/setting.ini", QSettings::NativeFormat);config.beginGroup("keys");if(config.childKeys().isEmpty()){config.setValue("ERROR", "#F00");config.setValue("FATAL", "#FF0");}config.endGroup();
}void Widget::filterKeyWord(const QString &key, const QString &color)
{QTextDocument *document = ui->textEdit->document();bool found = false;// undo previous change (if any)//document->undo();if (key.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(QColor(color));while (!highlightCursor.isNull() && !highlightCursor.atEnd()) {highlightCursor = document->find(key, highlightCursor,QTextDocument::FindWholeWords);if (!highlightCursor.isNull()) {found = true;//如果只是对关键字选中，则放开下面注释，并将下面select函数调用行注释掉
//                highlightCursor.movePosition(QTextCursor::WordRight,
//                                             QTextCursor::KeepAnchor);highlightCursor.select(QTextCursor::LineUnderCursor);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."));}}
}

ui文件，比较简单：

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0"><class>Widget</class><widget class="QWidget" name="Widget"><property name="geometry"><rect><x>0</x><y>0</y><width>800</width><height>600</height></rect></property><property name="windowTitle"><string>LogParseTool</string></property><layout class="QVBoxLayout" name="verticalLayout" stretch="0,1"><property name="spacing"><number>15</number></property><item><layout class="QHBoxLayout" name="horizontalLayout" stretch="0,1,0,0"><property name="spacing"><number>6</number></property><item><widget class="QLabel" name="label"><property name="text"><string>File:</string></property></widget></item><item><widget class="QLineEdit" name="path"/></item><item><widget class="QPushButton" name="selectBtn"><property name="text"><string>Select</string></property></widget></item><item><spacer name="horizontalSpacer"><property name="orientation"><enum>Qt::Horizontal</enum></property><property name="sizeType"><enum>QSizePolicy::Minimum</enum></property><property name="sizeHint" stdset="0"><size><width>20</width><height>20</height></size></property></spacer></item></layout></item><item><widget class="QTextEdit" name="textEdit"><property name="contextMenuPolicy"><enum>Qt::NoContextMenu</enum></property><property name="verticalScrollBarPolicy"><enum>Qt::ScrollBarAlwaysOff</enum></property><property name="horizontalScrollBarPolicy"><enum>Qt::ScrollBarAsNeeded</enum></property></widget></item></layout></widget><resources/><connections/>
</ui>

样式表，qss文件：

#Widget
{background-color: #4A4A4A;
}#Widget #label
{color: #fff;font-weight: bold;
}#path
{color: #fff;border-top: 0px solid red;border-bottom: 1px solid #cdcdcd;border-left: 0px solid red;border-right: 0px solid red;background: transparent;
}#textEdit
{border-top: 0px solid red;border-bottom: 1px solid #cdcdcd;border-left: 1px solid #cdcdcd;border-right: 1px solid #cdcdcd;border: none;background-color: #4A4A4A;
}#selectBtn, #setBtn
{color: black;background: #2d6699;
}