Symbian 用流操作文件

一、自定义的类

 

代码

class  TUserGroup
 {
public :
 TInt32 m_nGroupID;
 TBuf16 < 20 >  m_bufGroupName;

  void  ExternalizeL(RWriteStream &  aStream)  const ;
  void  InternalizeL(RReadStream &  aStream);
 };

void  TUserGroup::ExternalizeL(RWriteStream &  aStream)  const
 {
 aStream  <<  m_nGroupID;
 aStream  <<  m_bufGroupName;
 }

void  TUserGroup::InternalizeL(RReadStream &  aStream)
 {
 aStream  >>  m_nGroupID;
 aStream  >>  m_bufGroupName;
 }

 

二、写操作

 

代码

// 创建流式文件
   TFileName fnDataFile;
   fnDataFile.Copy(_L( " c:\\StreamExam.dat " ));

   RFs &  fs  =  CCoeEnv::Static() -> FsSession();

   RFileWriteStream fileWriteStream;
    // User::LeaveIfError(fileWriteStream.Create(fs,fnDataFile,EFileWrite));
   User::LeaveIfError(fileWriteStream.Replace(fs, fnDataFile,
     EFileWrite));
   fileWriteStream.PushL();

    // 外部化数据到文件中
   TInt32 nID;
   TBuf16 < 20 >  bufName;

   nID  =   10 ;
   bufName.Append(_L( " John " ));

   fileWriteStream  <<  nID;
   fileWriteStream  <<  bufName;

    // 外部化存储自定义类
   TUserGroup userGroup;
   userGroup.m_nGroupID  =   50 ;
   userGroup.m_bufGroupName.Copy(_L( " beijing " ));
   fileWriteStream  <<  userGroup;

    // 提交更改、释放资源
   fileWriteStream.CommitL();
   fileWriteStream.Pop();
   fileWriteStream.Release();

 

三、读的操作

代码

// 打开流式文件
   TFileName fnDataFile;
   fnDataFile.Copy(_L( " c:\\StreamExam.dat " ));
   
   RFs &  fs = CCoeEnv::Static() -> FsSession();
   
   RFileReadStream fileReadStream;
   User::LeaveIfError(fileReadStream.Open(fs,fnDataFile,EFileRead));
   fileReadStream.PushL();
   
    // 从文件中内部化数据
   TInt32 nID;
   TBuf16 < 20 >  bufName;
   
   fileReadStream  >>  nID;
   fileReadStream  >>  bufName;
   
   RDebug::Print(_L( " start\n " ));
   RDebug::Print(_L( " ID=%d  Name=%S\n " ),nID, & bufName);
   
    // 内部化自定义类
   TUserGroup userGroup;
   fileReadStream  >>  userGroup;
   RDebug::Print(_L( " GroupID=%d  GroupName=%S\n " ),userGroup.m_nGroupID, & (userGroup.m_bufGroupName));
   
    // 释放资源
   fileReadStream.Pop();
   fileReadStream.Release();
   RDebug::Print(_L( " end\n " ));