代码工厂@Code Blocks Forge

上回书说到IPlugin接口和众插件之间的关系，这里讲讲插件加载的过程。加载点在系统初始化时Framezhong 调用，上次也说过。这里主要是从PluginManager::Load() 说起。首先读取插件配置文件 config/plugins.xml，并将信息保存到std::map<wxString, PluginInfo> m_pluginsInfo中，这个成员m_pluginsInfo是属于PluginManager，这个map保存了插件名称和Pluginfo的映射关系。接着TagManagerST和LanguageST互相赋值。

现在进入重点循环，针对插件目录下的每个.dll/.so文件，会进行1）加载动态库；2）读插件信息；3）加载插件；4）调用插件相关创建toolbar和menu的函数。下面一一详述：

1）加载动态库：主要是通过clDynamicLibrary类，该类调用wxDynamicLibrary功能实现对动态链接库的加载，load()；

clDynamicLibrary *dl = new clDynamicLibrary();
            wxString fileName( files.Item( i ) );
            if ( !dl->Load( fileName ) ) {
                wxLogMessage( wxT( "Failed to load plugin’s dll: " ) + fileName );
                if (!dl->GetError().IsEmpty())
                    wxLogMessage(dl->GetError());
                delete dl;
                continue;
            }

2）读插件信息：还是wxDynamicLibrary的GetSymbol获得插件的函数指针GET_PLUGIN_INFO_FUNC和GET_PLUGIN_INTERFACE_VERSION_FUNC，并调用相应函数获取插件信息和接口版本号；

GET_PLUGIN_INFO_FUNC pfnGetPluginInfo = ( GET_PLUGIN_INFO_FUNC )dl->GetSymbol( wxT( "GetPluginInfo" ), &success );
            if ( !success ) {
                wxLogMessage(wxT("Failed to find GetPluginInfo in dll: ") + fileName);
                if (!dl->GetError().IsEmpty())
                    wxLogMessage(dl->GetError());
                delete dl;
                continue;
            }

            // load the plugin version method
            // if the methods does not exist, handle it as if it has value of 100 (lowest version API)
            int interface_version(100);
            GET_PLUGIN_INTERFACE_VERSION_FUNC pfnInterfaceVersion = (GET_PLUGIN_INTERFACE_VERSION_FUNC) dl->GetSymbol(wxT("GetPluginInterfaceVersion"), &success);
            if ( success ) {
                interface_version = pfnInterfaceVersion();
            } else {
                wxLogMessage(wxT("Failed to find GetPluginInterfaceVersion() in dll: ") + fileName);
                if (!dl->GetError().IsEmpty())
                    wxLogMessage(dl->GetError());
            }

            if ( interface_version != PLUGIN_INTERFACE_VERSION ) {
                wxLogMessage(wxString::Format(wxT("Version interface mismatch error for plugin ‘%s’. Plugin’s interface version is ‘%d’, CodeLite interface version is ‘%d’"),
                                              fileName.c_str(),
                                              interface_version,
                                              PLUGIN_INTERFACE_VERSION));
                delete dl;
                continue;
            }

3）故技重实，通过GetSymbol获得插件的CreatePlugin函数：

GET_PLUGIN_CREATE_FUNC pfn = ( GET_PLUGIN_CREATE_FUNC )dl->GetSymbol( wxT( "CreatePlugin" ), &success );

通过调用该函数加载并初始化插件，可见每个插件都必须实现这个CreatePlugin函数并export出来。

4）调用CreatePlugin之后，我们就得到IPlugin指针代表了这个插件实例（这个看起来很熟悉吧，不熟悉请参考前一篇IPlugin文章）

IPlugin *plugin = pfn( ( IManager* )this );之后就是想当然的调用plugin->CreateToolBar( Frame::Get() );创建工具条，和plugin->CreatePluginMenu( pluginsMenu );创建相应菜单。

循环结束后，最后一件事就是保存插件信息：

PluginsData pluginsData;
pluginsData.SetInfo(actualPlugins);
PluginConfig::Instance()->WriteObject(wxT("plugins_data"), &pluginsData);

插件加载结束了，如有任何疑问请联系Bryan Wu (cbforge at gmail.com)，转载也请注明出处： cbforge.com，Bryan Wu. 2009.

Happy Children’s Day to DuoDuo!

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