qml读写文件

利用qmlRegisterType接口注册一个文件操作类到Qml中，这样Qml就可以实现读写文件。

1 FileObject.h

代码语言：javascript复制

#ifndef FILE_OBJECT_H
#define FILE_OBJECT_H

#include <QObject>

class FileObject : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString source READ source WRITE setSource NOTIFY sourceChanged)
public:
    explicit FileObject(QObject *parent = 0);

    Q_INVOKABLE QString read();
    Q_INVOKABLE bool write(const QString& data);

    void setSource(const QString& source) { m_source = source; };
    QString source() { return m_source; }

signals:
    void sourceChanged(const QString& source);

private:
    QString m_source;
};

#endif // FILE_OBJECT_H

2 FileObject.cpp

代码语言：javascript复制

#include "FileObject.h"

#include <QFile>
#include <QTextStream>

FileObject::FileObject(QObject *parent) :
    QObject(parent)
{

}

QString FileObject::read()
{
    QString content;
    QFile file(m_source);
    if ( file.open(QIODevice::ReadOnly) ) {
        content = file.readAll();
        file.close();
    } 

    return content;
}

bool FileObject::write(const QString& data)
{
    QFile file(m_source);
    if ( file.open(QFile::WriteOnly | QFile::Truncate) ) {
        QTextStream out(&file);
           out<<data;
        file.close();
        return true;
    }
    else {
        return false;
    }
}

3 注册FileObject到Qml中

代码语言：javascript复制

#include "FileObject.h"

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

4 在Qml中使用FileObject实例

• 读文件内容 fileObject.read();
• 写文件 fileObject.write("Hello world!!!");

代码语言：javascript复制

import QtQuick 1.1
import FileObject 1.0

Rectangle {
    width: 640
    height: 320

    Text {
        id: myText
        anchors.centerIn: parent
    }

    FileObject{
        id: fileObject
        source: "test.txt"
    }

    MouseArea {
        anchors.fill: parent
        onClicked: {
            fileObject.write("Hello world!!!");
            myText.text =  fileObject.read();
        }
    }
}

qml 接口

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