wxWidgets流操作（二）wxTextInputStream和wxTextOutputStream

这一节很短，但是站在这一节wxWidgest流操作（一）wxFileInputStream与wxFileOutputStream 肩上的。

wxTextInputStream和wxTextOutputStream允许以行为单位来操纵流，特别适合于处理文本文件。

利用这节的界面，打开源码后找到菜单File->&Open 子项的代码：

void StreamAppFrame::OnStreamClick(wxCommandEvent& event)
{
    wxString filename(wxT("streamMain.cpp"));
    wxString dummyfile(wxT("dummy.cpp"));

    wxFileInputStream inStream(filename);
    wxFileOutputStream outStream(dummyfile);

    
    int byteCount=inStream.GetLength();
    static char buffer[1024*1024*1024];
    wxString content;
    while(byteCount>0)
    {
        size_t bytesToRead=wxMin((size_t)sizeof(buffer),byteCount);

        if(inStream.Read((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
        {
            if(outStream.Write((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
            {
                content=wxString::FromUTF8(buffer,bytesToRead);
                byteCount-=bytesToRead;
            }

            *text1<<content;
            wxLogStatus(wxT("Copy file successfully."));
        }
        else
        {
            wxLogStatus(wxT("Failed to copy file."));
        }
    }


    *text1<<wxT("\n文件读取成功！\n");

  ｝

从int byteCount开始至结束注释掉。下面将使用wxTextInputStream和wxTextOutputStream来重新实现该模块的功能以做比较。

void StreamAppFrame::OnStreamClick(wxCommandEvent& event)
{
    wxString filename(wxT("streamMain.cpp"));
    wxString dummyfile(wxT("dummy.cpp"));

    wxFileInputStream inStream(filename);
    wxFileOutputStream outStream(dummyfile);

    /*
    int byteCount=inStream.GetLength();
    static char buffer[1024*1024*1024];
    wxString content;
    while(byteCount>0)
    {
        size_t bytesToRead=wxMin((size_t)sizeof(buffer),byteCount);

        if(inStream.Read((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
        {
            if(outStream.Write((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
            {
                content=wxString::FromUTF8(buffer,bytesToRead);
                byteCount-=bytesToRead;
            }

            *text1<<content;
            wxLogStatus(wxT("Copy file successfully."));
        }
        else
        {
            wxLogStatus(wxT("Failed to copy file."));
        }
    }


    *text1<<wxT("\n文件读取成功！\n");

    */

  ...

}

wxTextInputStream和wxTextOutputStream的头文件为<wx/txtstrm.h>,将其加到源文件里来。

wxTextInputStream和wxTextOutputStream的构造函数分别需要传入wxFileInputStream/wxFFileInputStream ,wxFileOutputStream/wxFFileOutputStream的实例，然后输入流时可以用wxTextInputStream.ReadLine()来从流中读取一行,用wxTextOutputStream.WriteString(wxString&)来将字符串输出到终端，两种流都重载了流操作符<<和>>。

    wxFFileInputStream fin(filename);
    wxFFileOutputStream fout(wxT("dummy1.cpp"));
    wxTextInputStream cin(fin);
    wxTextOutputStream cout(fout);

    while(1)
    {
        wxString got=cin.ReadLine();
        if(fin.Eof() && got.empty())
            break;


        *text1<<got<<wxT("\n");
        cout<<got<<wxT("\n");



    }
    text1->AppendText(wxT("搞定。"));
    wxLogStatus(wxT("读取并写入流完成。"));

添加上面的代码到OnStreamClick方法的最后，重新编译，运行，一切OK！但实现却简单了很多，是不是。

以下为OnStreamClick的完整代码：



void StreamAppFrame::OnStreamClick(wxCommandEvent& event)
{
    wxString filename(wxT("streamMain.cpp"));
    wxString dummyfile(wxT("dummy.cpp"));

    wxFileInputStream inStream(filename);
    wxFileOutputStream outStream(dummyfile);

    /*
    int byteCount=inStream.GetLength();
    static char buffer[1024*1024*1024];
    wxString content;
    while(byteCount>0)
    {
        size_t bytesToRead=wxMin((size_t)sizeof(buffer),byteCount);

        if(inStream.Read((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
        {
            if(outStream.Write((void*)buffer,bytesToRead).GetLastError()==wxSTREAM_NO_ERROR)
            {
                content=wxString::FromUTF8(buffer,bytesToRead);
                byteCount-=bytesToRead;
            }

            *text1<<content;
            wxLogStatus(wxT("Copy file successfully."));
        }
        else
        {
            wxLogStatus(wxT("Failed to copy file."));
        }
    }


    *text1<<wxT("\n文件读取成功！\n");

    */
    wxFFileInputStream fin(filename);
    wxFFileOutputStream fout(wxT("dummy1.cpp"));
    wxTextInputStream cin(fin);
    wxTextOutputStream cout(fout);

    while(1)
    {
        wxString got=cin.ReadLine();
        if(fin.Eof() && got.empty())
            break;


        *text1<<got<<wxT("\n");
        cout<<got<<wxT("\n");



    }
    text1->AppendText(wxT("搞定。"));
    wxLogStatus(wxT("读取并写入流完成。"));
}