Question

如何在QML应用中读写文件

Answer 1

1）创建一个简单的模版应用

我们使用Ubuntu SDK的模版来创建一个最简单的应用：

我们选择“QML App with C++ plugin”模版来做我们的应用。

2）添加文件读写的文件到项目中

我们添加如下的C++ "FileIO类到我们的backend plugin中：

#ifndef FILEIO_H
#define FILEIO_H

#include <QObject>
#include <QTextCodec>
#include <QDebug>

class FileIO : public QObject
{
Q_OBJECT

public:
Q_PROPERTY(QString source
READ source
WRITE setSource
NOTIFY sourceChanged)
explicit FileIO(QObject *parent = 0);

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

QString source() { return mSource; };

public slots:
void setSource(const QString& source) { mSource = source; };

signals:
void sourceChanged(const QString& source);
void error(const QString& msg);

private:
QString getenv(const QString envVarName) const;

private:
QString mSource;
QString datapath;
};

inline QString GBK2UTF8(const QString &inStr)
{
QList<QByteArray> codecs = QTextCodec::availableCodecs();

for ( int i = 0; i < codecs.length(); i ++ ) {
// qDebug() << "codec: " + QTextCodec::codecForMib(1015)->toUnicode(codecs.at(i));
qDebug() << "codec: " << QString::fromLocal8Bit(codecs.at(i));
}

QTextCodec *gbk = QTextCodec::codecForName("GBK");

QTextCodec::setCodecForLocale(QTextCodec::codecForLocale());
// QTextCodec *utf8 = QTextCodec::codecForName("UTF-8");

QString g2u = gbk->toUnicode(gbk->fromUnicode(inStr)); // gbk convert utf8
return g2u;
}

#endif // FILEIO_H

#include "fileio.h"
#include <QFile>
#include <QTextStream>
#include <QDebug>
#include <QFileInfo>
#include <QTextCodec>

FileIO::FileIO(QObject *parent) : QObject(parent)
{
datapath = getenv("TMPDIR") + "/";
qDebug() << "datapath: " + datapath;
}

QString FileIO::read()
{
qDebug() << "reading ....!";

if (mSource.isEmpty()){
emit error("source is empty");
return QString();
}

QFile file(datapath + mSource);
QFileInfo fileInfo(file.fileName());
qDebug() << "file path: " << fileInfo.absoluteFilePath();

QString fileContent;
if ( file.open(QIODevice::ReadOnly) ) {
QString line;

QTextCodec *gbk = QTextCodec::codecForName("GBK");
QTextStream t( &file );
t.setCodec(gbk);

do {
line = t.readLine();
fileContent += line;