Qt获取文件属性

一、综述。
在Qt中QFileInfo类提供了系统独立的文件信息。QFileInfo提供了文件在文件系统中的文件名称与位置信息，以及文件的权限、目录、文件或符号连接等，也提供了文件的大小、创建时间、最后修改时间、最后访问时间等信息。QFileInfo可以使用绝对路径和相对路径来指向同一个文件，绝对路径以“/”开头（在windows中以磁盘符号开头），相对路径则以目录名或文件名开头，isRelative()方法可以用来判断QFileInfo使用的是绝对路径还是相对路径。makAbsolute()方法可以用来将相对路径转化为绝对路径。

为了加快执行效率，QFileInfo可以将文件信息进行一次读取缓存，这样后续的访问就不需要持续访问文件了，但是由于文件在读取信息之后可能被其他程序或本程序改变属性，因此QFileInfo通过refresh()方法提供了一种刷新机制可以更新文件信息，用户也可以通过setCaching()方法关闭这种缓冲功能。

文件属性可以通过isFile()、isDir()和isSysLink()获得，对于符号连接，sysLinkTarget()方法可以获得符号连接指向的文件名称。

QFileInfo还提供了对文件路径的有效分离的方法，如下：

QFileInfo fi( “/tmp/archive.tar.gz” );

QString absoluteFilePath = fi.absoluteFilePath();

//absoluteFilePath = “/tmp/archive.tar.gz”

QString absolutePath = fi.absolutePath(); //absolutePath = “/tmp”

QString baseName = fi.baseName(); //baseName = “archive”

QString completeBaseName = fi.completeBaseName();

//completeBaseName = “archive.tar”

QString completeSuffix = fi.completeSuffix();

//completeSuffix = “tar.gz”

QString fileName = fi.fileName(); //fileName = “archive.tar.gz”

QString filePath = fi.filePath(); //filePath = “/tmp/archive.tar.gz”

QString path = fi.path(); //path = “/tmp”

QString suffix = fi.suffix(); //suffix = “gz”

文件的日期可以由created()、lastModified()、lastRead()等方法获得，文件的存取权限可以由isReadable()、isWritable()和i***ecutable()的方法获得，文件的所有权限可以由owner()、ownerId()、group()、groupId()等方法获得。Permission()方法可以用来测试一个文件的权限。

二、实例





“fileInfo.h”代码如下：

class fileInfo : public QDialog

{

Q_OBJECT

public:

fileInfo(QWidget *parent = 0, Qt::WFlags flags = 0);

~fileInfo();

protected slots:

void slotFile();

void slotGet();

private:

void getFileInformation( QString file );

private:

QLabel * pLabelFileName;

QLineEdit * pLineEditFileName;

QPushButton * pPushButtonFile;

QLabel * pLabelSize;

QLineEdit * pLineEditSize;

QLabel * pLabelCreated;

QLineEdit * pLineEditCreated;

QLabel * pLabelLastModified;

QLineEdit * pLineEditLastModified;

QLabel * pLabelLastRead;

QLineEdit * pLineEditLastRead;

QLabel * pLabelProperty;

QCheckBox * pCheckBoxIsDir;

QCheckBox * pCheckBoxIsFile;

QCheckBox * pCheckBoxIsSymLink;

QCheckBox * pCheckBoxIsHidden;

QCheckBox * pCheckBoxIsReadable;

QCheckBox * pCheckBoxIsWritable;

QCheckBox * pCheckBoxI***ecutable;

QPushButton * pPushButtonGet;

};

“fileInfo.cpp”代码如下：

fileInfo::fileInfo(QWidget *parent, Qt::WFlags flags)

: QDialog(parent, flags)

{

setWindowTitle( tr( "FileInformation" ) );

pLabelFileName = new QLabel();

pLabelFileName->setText( tr( "File Name:" ) );

pLineEditFileName = new QLineEdit();

pPushButtonFile = new QPushButton( this );

pPushButtonFile->setText( tr( "File" ) );

pLabelSize = new QLabel();

pLabelSize->setText( tr( "Size:" ) );

pLineEditSize = new QLineEdit();

pLabelCreated = new QLabel();

pLabelCreated->setText( "Created:" );

pLineEditCreated = new QLineEdit();

pLabelLastModified = new QLabel();

pLabelLastModified->setText( tr( "LastModified:" ) );

pLineEditLastModified = new QLineEdit();

pLabelLastRead = new QLabel();

pLabelLastRead->setText( tr( "LastRead:" ) );

pLineEditLastRead = new QLineEdit();

pLabelProperty = new QLabel();

pLabelProperty->setText( tr( "Property:" ) );

pCheckBoxIsDir = new QCheckBox();

pCheckBoxIsDir->setText( tr( "Dir" ) );

pCheckBoxIsFile = new QCheckBox();

pCheckBoxIsFile->setText( tr( "File" ) );

pCheckBoxIsSymLink = new QCheckBox();

pCheckBoxIsSymLink->setText( tr( "SymLink" ) );

pCheckBoxIsHidden = new QCheckBox();

pCheckBoxIsHidden->setText( tr( "Hidden" ) );

pCheckBoxIsReadable = new QCheckBox();

pCheckBoxIsReadable->setText( tr( "Readable" ) );

pCheckBoxIsWritable = new QCheckBox();

pCheckBoxIsWritable->setText( tr( "Writable" ) );

pCheckBoxI***ecutable = new QCheckBox();

pCheckBoxI***ecutable->setText( tr( "Executable" ) );

pPushButtonGet = new QPushButton();

pPushButtonGet->setText( tr( "Get FileInformation" ) );

QGridLayout * pLayout = new QGridLayout( this );

pLayout->addWidget( pLabelFileName, 0, 0, 1, 2 );

pLayout->addWidget( pLineEditFileName, 0, 2, 1, 4 );

pLayout->addWidget( pPushButtonFile, 0, 6, 1, 1 );

pLayout->addWidget( pLabelSize, 1, 0, 1, 2 );

pLayout->addWidget( pLineEditSize, 1, 2, 1, 5 );

pLayout->addWidget( pLabelCreated, 2, 0, 1, 2 );

pLayout->addWidget( pLineEditCreated, 2, 2, 1, 5 );

pLayout->addWidget( pLabelLastModified, 3, 0, 1, 2 );

pLayout->addWidget( pLineEditLastModified, 3, 2, 1, 5 );

pLayout->addWidget( pLabelLastRead, 4, 0, 1, 2 );

pLayout->addWidget( pLineEditLastRead, 4, 2, 1, 5 );

pLayout->addWidget( pLabelProperty, 5, 0, 1, 2 );

pLayout->addWidget( pCheckBoxIsDir, 6, 0 );

pLayout->addWidget( pCheckBoxIsFile, 6, 1 );

pLayout->addWidget( pCheckBoxIsSymLink, 6, 2 );

pLayout->addWidget( pCheckBoxIsHidden, 6, 3 );

pLayout->addWidget( pCheckBoxIsReadable, 6, 4 );

pLayout->addWidget( pCheckBoxIsWritable, 6, 5 );

pLayout->addWidget( pCheckBoxI***ecutable, 6, 6 );

pLayout->addWidget( pPushButtonGet, 7, 0, 1, 7 );

setLayout( pLayout );

connect( pPushButtonFile, SIGNAL( clicked() ), this, SLOT( slotFile() ) );

connect( pPushButtonGet, SIGNAL( clicked() ), this, SLOT( slotGet() ) );

}

fileInfo::~fileInfo()

{

}

void fileInfo::slotFile()

{

QString sFilePath = QFileDialog::getOpenFileName( this, "open file dialog", "", "file (*)" );

pLineEditFileName->setText( sFilePath.toAscii() );

}

void fileInfo::slotGet()

{

getFileInformation( pLineEditFileName->text() );

}

void fileInfo::getFileInformation( QString file )

{

QFileInfo info( file );

pLineEditSize->setText( QString::number( info.size() ) );

pLineEditCreated->setText( info.created().toString() );

pLineEditLastModified->setText( info.lastModified().toString() );

pLineEditLastRead->setText( info.lastRead().toString() );

pCheckBoxIsDir->setCheckState( info.isDir() ? Qt::Checked : Qt::Unchecked );

pCheckBoxIsFile->setCheckState( info.isFile() ? Qt::Checked : Qt::Unchecked );

pCheckBoxIsSymLink->setCheckState( info.isSymLink() ? Qt::Checked : Qt::Unchecked );

pCheckBoxIsHidden->setCheckState( info.isHidden() ? Qt::Checked : Qt::Unchecked );

pCheckBoxIsReadable->setCheckState( info.isReadable() ? Qt::Checked : Qt::Unchecked );

pCheckBoxIsWritable->setCheckState( info.isWritable() ? Qt::Checked : Qt::Unchecked );

pCheckBoxI***ecutable->setCheckState( info.i***ecutable() ? Qt::Checked : Qt::Unchecked );

}