Qt获取文件属性

Qt获取文件属性

文档名称	Qt获取文件属性
创建时间	2012-9-13
修改时间	2012-9-13
创建人	Baifx
简介（收获）	QFileInfo类的使用

       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 );

}