QML文件读写控件(预览版)

妖狐艹你老母 2023-06-24 01:30 3阅读 0赞

> 旨在解决QML不能读写文件的问题。目前为预览版本(文末源码)，供大家一起参考学习。

**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**。

![demo.gif][]

## 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
        }
    }

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[demo.gif]: https://img-blog.csdnimg.cn/2019122012411555.gif