Symbian 用流操作文件

一、自定义的类

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

//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

//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"));