QML File组件通过source的属性来设置需要读写的文件

File组件通过source的属性来设置需要读写的文件，还可以通过访问/设置text的内容来读取/写入文件。

使用

• 注册File组件到Qml中:

qmlRegisterType<File>("MyModel", 1, 0, "File");

• 导入File组件：

import MyModel 1.0

• 使用：

/* 创建实例 */
File {
    id: file
    source: "D:/Document/hello.txt"
}

TextArea {
    anchors.fill: parent
    font.pixelSize: 30
    onTextChanged: file.text = text
    Component.onCompleted: text = file.text
}

源码

• main.cpp

#include "File.h"

int main(int argc, char *argv[])
{
    ...
    qmlRegisterType<File>("MyModel", 1, 0, "File");
    ...
}

• File.h

#ifndef QT_HUB_FILE_H
#define QT_HUB_FILE_H

#include <QObject>

class File : public QObject
{
    Q_OBJECT
public:
    File();

    Q_PROPERTY(QString source READ source WRITE setSource NOTIFY sourceChanged)
    Q_PROPERTY(QString text   READ text   WRITE setText   NOTIFY textChanged)

    QString source() const;
    void setSource(const QString &source);

    QString text() const;
    void setText(const QString &text);

signals:
    void sourceChanged();
    void textChanged();

private slots:
    void readFile();

private:
    QString m_source;
    QString m_text;
};

#endif // FILE_H

• File.cpp

#include "File.h"

#include <QFile>
#include <QDebug>

File::File()
{
    connect(this, SIGNAL(sourceChanged()), this, SLOT(readFile()));
}

void File::setSource(const QString &source)
{
    m_source = source;
    emit sourceChanged();
}

QString File::source() const
{
    return m_source;
}

void File::setText(const QString &text)
{
    QFile file(m_source);
    if (!file.open(QIODevice::WriteOnly)) {
        m_text = "";
        qDebug() << "Error:" << m_source << "open failed!";
    }
    else {
        qint64 byte = file.write(text.toUtf8());
        if (byte != text.toUtf8().size()) {
            m_text = text.toUtf8().left(byte);
            qDebug() << "Error:" << m_source << "open failed!";
        }
        else {
            m_text = text;
        }

        file.close();
    }

    emit textChanged();
}

void File::readFile()
{
    QFile file(m_source);
    if (!file.open(QIODevice::ReadOnly)) {
        m_text = "";
        qDebug() << "Error:" << m_source << "open failed!";
    }

    m_text = file.readAll();
    emit textChanged();
}

QString File::text() const
{
    return m_text;
}

• main.qml

...
import QtQuick 2.0
import QtQuick.Window 2.0
import QtQuick.Controls 2.0
import MyModel 1.0

Window {
    visible: true
    width: 480
    height: 320
    title: qsTr("File组件 by Qt君")

    File {
        id: file
        source: "D:/Document/hello.txt"
    }

    TextArea {
        anchors.fill: parent
        font.pixelSize: 30
        onTextChanged: file.text = text
        Component.onCompleted: text = file.text
    }
}