qt实现文件比较

功能点

1.鼠标拖动到文本区进行读取显示

2.高亮第二个文本区的文本

核心逻辑：

每次读取文件后将文本内容存到一个QStringList中 按换行分割。

确定两个列表中较长的那个的长度。这确保在比较两个文件时，即使一个文件比另一个长，也能进行完整的行比较。

检查三种情况来判定两个文件在某行是否不同：i < lines1.size() && i >= lines2.size()如果 lines1 有这一行，但 lines2 已经没有更多行了。

结果展示：

#ifndef MYEDIT_H
#define MYEDIT_H


#include <QApplication>
#include <QWidget>
#include <QVBoxLayout>
#include <QPlainTextEdit>
#include <QDragEnterEvent>
#include <QDropEvent>
#include <QMimeData>
#include <QFile>
#include <QTextStream>
#include <QDebug>
#include<QPainter>
class MyEdit : public QPlainTextEdit
{
    Q_OBJECT
public:
    MyEdit(QWidget *parent = nullptr);
protected:
    void dragEnterEvent(QDragEnterEvent *event) override;
    void dropEvent(QDropEvent *event) override;

private:
    int lineNumberAreaWidth();
public:
    QStringList fileLines;

private:
    void loadFile(const QString &fileName);

};

#endif // MYEDIT_H

#include "MyEdit.h"
MyEdit::MyEdit(QWidget *parent): QPlainTextEdit(parent)
{
    setAcceptDrops(true);

}

void MyEdit::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasUrls()) {
        event->acceptProposedAction();
    }
}

void MyEdit::dropEvent(QDropEvent *event)
{
    const QMimeData *mimeData = event->mimeData();
    if (mimeData->hasUrls()) {
        QList<QUrl> urlList = mimeData->urls();
        if (urlList.size() == 1) {  // 只处理单个文件
            QString fileName = urlList.at(0).toLocalFile();
            if (!fileName.isEmpty()) {
                loadFile(fileName);
                event->acceptProposedAction();
            }
        }
    }
}

void MyEdit::loadFile(const QString &fileName)
{

    QFile file(fileName);
    if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
        QTextStream in(&file);
        in.setCodec("UTF-8");
        QString content = in.readAll();
        setPlainText(content);
        file.close();

        // 清空旧的内容，并存储新的每一行
        fileLines.clear();
        fileLines = content.split('\n', QString::KeepEmptyParts);
    } else {
        qDebug() << "Failed to open file:" << fileName;
    }
}

#ifndef FILECOMPARER_H
#define FILECOMPARER_H

#include <QPushButton>
#include <QWidget>
#include <QTextCursor>
#include <QTextDocument>
#include <QTextBlock>
#include<QHBoxLayout>
#include<QSpacerItem>
#include"MyEdit.h"
class FileComparer : public QWidget
{
    Q_OBJECT

public:
    FileComparer(QWidget *parent = nullptr);
    ~FileComparer();
private:
    void initUI();
    void compareAndHighlight();
    void highlightLine(const QStringList &lines1, const QStringList &lines2);
private:
    MyEdit *m_beforeFile;
    MyEdit *m_afterFile;
    QPushButton *compareButton;
};
#endif // FILECOMPARER_H

#include "filecomparer.h"

FileComparer::FileComparer(QWidget *parent)
    : QWidget(parent)
{
    initUI();
}

FileComparer::~FileComparer()
{
}

void FileComparer::initUI()
{
    this->resize(800,650);
    QVBoxLayout *layout = new QVBoxLayout(this);

    m_beforeFile = new MyEdit(this);
    m_afterFile = new MyEdit(this);
    compareButton = new QPushButton("比较文件", this);

    QHBoxLayout *hb1=new QHBoxLayout;
    hb1->addWidget(m_beforeFile);
    hb1->addWidget(m_afterFile);

    QHBoxLayout *hb2=new QHBoxLayout;
    hb2->addWidget(compareButton);
    hb2->addSpacerItem(new QSpacerItem(20, 20, QSizePolicy::Expanding));

    layout->addLayout(hb1);
    layout->addLayout(hb2);
    setLayout(layout);
    this->m_afterFile->setStyleSheet("border:2px solid red");
    this->m_beforeFile->setStyleSheet("border:2px solid blue");
    connect(compareButton, &QPushButton::clicked, this, &FileComparer::compareAndHighlight);
}



void FileComparer::compareAndHighlight()
{
     highlightLine(m_beforeFile->fileLines,m_afterFile->fileLines);
}

void FileComparer::highlightLine(const QStringList &lines1, const QStringList &lines2)
{
    int maxLines = qMax(lines1.size(), lines2.size());

    QTextCharFormat format;
    format.setBackground(Qt::yellow);
    for (int i = 0; i < maxLines; ++i) {
            if ((i < lines1.size() && i >= lines2.size()) || (i >= lines1.size() && i < lines2.size()) ||
                (i < lines1.size() && i < lines2.size() && lines1[i].trimmed() != lines2[i].trimmed())) {
                QTextCursor cursor(m_afterFile->document()->findBlockByLineNumber(i));
                cursor.select(QTextCursor::LineUnderCursor);
                cursor.mergeCharFormat(format);
            }
        }

}