Linux插件框架实验报告

电子科技大学实验报告学生姓名：学号：指导教师：实验地点：A2-412 实验时间：2012.01.04一、实验室名称：Linux环境高级编程实验室二、实验项目名称：插件框架实验三、实验学时：4学时四、实验目的：学习和实践插件框架的开发。

理解插件的工作原理，为进一步开发高可用，高复杂度的插件打下基础。

五、实验内容：1、使用动态链接库实现打印功能：开发一个程序，向屏幕打印“Hello World”；在不重新编译链接原程序的前提下，将打印的文字改为“Hello China”。

2、使用动态链接库实现自定义打印功能：同时要打印“Hello World”，打印“Hello China”，甚至同时打印未来才会增加的其他打印信息，打印信息的链接库放在一个固定目录中，遍历这个目录，获取所有动态链接库。

打印未来的这些信息，也不能重新编译链接原程序。

3、1）通过命令行方式：./a.out help，输出所有插件实现的功能ID，以及该功能ID对应的功能描述。

2）通过命令行方式：./a.out FuncID，调用具体打印功能（每个插件导出GetID接口）。

4、将插件导出的Print、GetID、Help三个函数放在一个类中，主程序需要使用多个容器分别保存这些函数地址，让插件外部获取该类的对象。

综合练习：实现一个软件系统，该系统可对文件进行统计分析。

究竟对文件进行什么样的统计分析，最终用户自己也不是很清楚，目前只知道需要统计文件的行数。

也就是说，本软件系统将会随时面临，增加文件统计新功能的难题。

请结合本实验内容，设计并实现这样一个面向文件统计功能的插件系统。

（需要实现的插件包括：统计某个文件的行数，统计某个文件的字节数）六、实验步骤：程序1：A.h:extern "c" void f();a2.cpp：#include<iostream>#include"a.h"using namespace std;void f(){cout << "hello,China!" << endl;}A1.cpp:#include<iostream>#include"a.h"using namespace std;void f(){cout << "Hello,Word" << endl;}Main.cpp:#include"a.h"#include<dlfcn.h>#include<iostream>using namespace std;int main(){void *handle = dlopen("./libtest.so", RTLD_LAZY);if(0 == handle){cout << "dlopen error" << endl;return 0;}typedef void (*Fun)();Fun f1 = (Fun)dlsym(handle, "f");if(0 == f1){cout << "f1 error" << endl;char *str = dlerror();cout << str << endl;}(*f1)();dlclose(handle);return 0;}程序运行结果如图1所示：图1：字符的变换程序2：A1.cpp:#include<iostream>using namespace std;extern"C" void f(){cout << "Hello world" << endl;}A2.cpp:#include<iostream>using namespace std;extern "C" void f(){cout << "Hello,china!" << endl;}A3.cpp:#include<iostream>using namespace std;extern "C" void f(){cout << "Hello 333" << endl;}A4.cpp:#include<iostream>using namespace std;extern "C" void f(){cout << "Hello 4444" << endl;}Test2.cpp:#include<dlfcn.h>#include<iostream>#include<dirent.h>#include<stdio.h>#include<string.h>using namespace std;int main(){char path[260];DIR *dir;struct dirent *ptr;dir=opendir("/root/test/test4/plug2/plugin/");while((ptr=readdir(dir))!=NULL){if ((strcmp(ptr->d_name,"..")==0)||(strcmp(ptr->d_name,".")==0)){continue;}sprintf(path,"/root/test/test4/plug2/plugin/%s", ptr->d_name);void *handle = dlopen(path, RTLD_LAZY);if(0 == handle){cout << "dlopen error" << endl;return 0;}typedef void (*Fun)();Fun pf = (Fun)dlsym(handle, "f");if(0 == pf){cout << "pf error" << endl;char *str = dlerror();cout << str << endl;return 0;}(*pf)();dlclose(handle);}closedir(dir);}程序运行结果如图2所示：图2：插件的遍历程序3：a1.cpp:#include <iostream>using namespace std;const int FUNC_ID = 1;extern "C" void f(){cout << "Hello World!" << endl;}extern "C" void Help(){cout << "Function ID " << FUNC_ID << " : This function prints Hello World." << endl;}a2.cpp:#include <iostream>using namespace std;const int FUNC_ID = 2;extern "C" void f(){cout << "Hello China!" << endl;}extern "C" void Help(){cout << "Function ID " << FUNC_ID << " This function prints hello china." << endl;}CPluginEnumerator.cpp#include "CPluginEnumerator.h"#include <dirent.h>#include <string.h>#include <iostream>#include <stdio.h>CPluginEnumerator::CPluginEnumerator(){}CPluginEnumerator::~CPluginEnumerator(){}bool CPluginEnumerator::GetPluginNames(vector<string>& vstrPluginNames){DIR *dir = opendir("/root/test/test4/plug3/plugin");if(dir == 0)return false;for(;;){struct dirent *ptr = readdir(dir);if(ptr == 0)break;if((strcmp(ptr->d_name, ".") == 0)||(strcmp(ptr->d_name, "..") == 0)) continue;char path[260];sprintf(path, "/root/test/test4/plug3/plugin/%s", ptr->d_name);vstrPluginNames.push_back(path);}closedir(dir);return true;}Test.cpp:#include <dlfcn.h>#include <iostream>#include "CPluginEnumerator.h"#include <string.h>#include <stdio.h>using namespace std;int main(int argc, char **argv){char path [260];if(argc != 2)return 0;if(strcmp(argv[1], "help") == 0){vector<string> vstrPluginNames;CPluginEnumerator enumerator;if(!enumerator.GetPluginNames(vstrPluginNames)){cout << "GetPluginNames error" << endl;return 0;}for(int i = 0; i< vstrPluginNames.size(); i++){void *handle = dlopen(vstrPluginNames[i].c_str(), RTLD_LAZY);if(handle == 0){cout << "dlopen error" << endl;return 0;}typedef void (*FUNC_HELP)();FUNC_HELP dl_help = (FUNC_HELP)dlsym(handle, "Help");if(dl_help == 0){cout << "dlsym error" << endl;return 0;}(dl_help)();dlclose(handle);}}else if(strcmp(argv[1], "1") == 0){sprintf(path, "/root/test/test4/plug3/plugin/%s", "a1.so");void *handle = dlopen(path, RTLD_LAZY);if(handle == 0){cout << "dlopen error" << endl;return 0;}typedef void (*FUNC_PRINT)();FUNC_PRINT dl_print = (FUNC_PRINT)dlsym(handle, "f");if(dl_print == 0){cout << "dlsym error" << endl;return 0;}(dl_print)();dlclose(handle);}else if(strcmp(argv[1], "2") == 0)// 得到第二个func的参数{sprintf(path, "/root/test/test4/plug3/plugin/%s", "a2.so");void *handle = dlopen(path, RTLD_LAZY);if(handle == 0){cout << "dlopen error" << endl;return 0;}typedef void (*FUNC_PRINT)();FUNC_PRINT dl_print = (FUNC_PRINT)dlsym(handle, "f");if(dl_print == 0){cout << "dlsym error" << endl;return 0;}(dl_print)();dlclose(handle);}return 0;}程序运行结果如图3所示：图3：插件输出程序4：CPluginEnumerator.h:#ifndef CPLUGINENUMERATOR_H#define CPLUGINENUMERATOR_H#include <vector>#include <string>using namespace std;class CPluginEnumerator{public:CPluginEnumerator();virtual ~CPluginEnumerator();bool GetPluginNames(vector<string>& vstrPluginNames);};#endifCPluginEnumerator.cpp：#include "CPluginEnumerator.h"#include <dirent.h>#include <string.h>CPluginEnumerator::CPluginEnumerator(){}CPluginEnumerator::~CPluginEnumerator(){}bool CPluginEnumerator::GetPluginNames(vector<string>& vstrPluginNames) {DIR *dir = opendir("./plugin");if(dir == 0)return false;for(;;){struct dirent *pentry = readdir(dir);if(pentry == 0)break;if(strcmp(pentry->d_name, ".") == 0)continue;if(strcmp(pentry->d_name, "..") == 0)continue;string str = "./plugin/";str += pentry->d_name;vstrPluginNames.push_back(str);}closedir(dir);return true;}CPluginController.h#ifndef CPLUGINCONTROLLER_H#define CPLUGINCONTROLLER_H#include <vector>class IPrintPlugin;class CPluginController{public:CPluginController(void);virtual ~CPluginController(void);bool InitializeController(void);bool UninitializeController(void);bool ProcessHelp(void);bool ProcessRequest(int FunctionID); private:std::vector<void *> m_vhForPlugin;std::vector<IPrintPlugin*> m_vpPlugin; };#endifCPluginController.cpp#include "CPluginController.h"#include "CPluginEnumerator.h"#include "IPrintPlugin.h"#include "dlfcn.h" CPluginController::CPluginController(void) {}CPluginController::~CPluginController(void){}bool CPluginController::InitializeController(void){std::vector<std::string> vstrPluginNames;CPluginEnumerator enumerator;if(!enumerator.GetPluginNames(vstrPluginNames))return false;for(unsigned int i=0 ; i<vstrPluginNames.size(); i++){typedef int (*PLUGIN_CREATE)(IPrintPlugin**);PLUGIN_CREATE CreateProc;IPrintPlugin *pPlugin = NULL;void* hinstLib = dlopen(vstrPluginNames[i].c_str(), RTLD_LAZY);if(hinstLib != NULL){m_vhForPlugin.push_back(hinstLib);CreateProc = (PLUGIN_CREATE)dlsym(hinstLib, "CreateObj");if(NULL != CreateProc){(CreateProc)(&pPlugin);if(pPlugin != NULL){m_vpPlugin.push_back(pPlugin);}}}}return true;}bool CPluginController::ProcessRequest(int FunctionID)for(unsigned int i = 0; i < m_vpPlugin.size(); i++){if(m_vpPlugin[i]->GetID() == FunctionID){m_vpPlugin[i]->Print();break;}}return true;}bool CPluginController::ProcessHelp(void){std::vector<std::string> vstrPluginNames;CPluginEnumerator enumerator;if(!enumerator.GetPluginNames(vstrPluginNames))return false;for(unsigned int i=0 ; i<vstrPluginNames.size(); i++){typedef int (*PLUGIN_CREATE)(IPrintPlugin**);PLUGIN_CREATE CreateProc;IPrintPlugin *pPlugin = NULL;void* hinstLib = dlopen(vstrPluginNames[i].c_str(), RTLD_LAZY);if(hinstLib != NULL){CreateProc = (PLUGIN_CREATE)dlsym(hinstLib, "CreateObj");if(NULL != CreateProc){(CreateProc)(&pPlugin);if(pPlugin != NULL){pPlugin->Help();}}dlclose(hinstLib);}}return true;}bool CPluginController::UninitializeController(){for(unsigned int i = 0; i < m_vhForPlugin.size(); i++) {dlclose(m_vhForPlugin[i]);}return true;}IPrintPlugin.h#pragma onceclass IPrintPlugin{public:IPrintPlugin();virtual ~IPrintPlugin();virtual void Help() = 0;virtual void Print() = 0;virtual int GetID() = 0;};IPrintPlugin.cpp#include "IPrintPlugin.h"IPrintPlugin::IPrintPlugin(){}IPrintPlugin::~IPrintPlugin(){}Function.cpp#include <iostream>#include "IPrintPlugin.h"using namespace std;const int FUNC_ID = 1;class CPrintPlugin : public IPrintPlugin{public:CPrintPlugin(){}virtual ~CPrintPlugin(){}virtual void Print(){cout << "Hello World!" << endl;}virtual void Help(){cout << "Function ID " << FUNC_ID << " : This function will print hello world." << endl;}virtual int GetID(void){return FUNC_ID;}};extern "C" void CreateObj(IPrintPlugin **ppPlugin){static CPrintPlugin plugin;*ppPlugin = &plugin;}function1.cpp#include <iostream>#include "IPrintPlugin.h"const int FUNC_ID = 2;class CPrintPlugin : public IPrintPlugin{public:CPrintPlugin(){}virtual ~CPrintPlugin(){}virtual void Print(){cout << "Hello China!" << endl;}virtual void Help(){cout << "Function ID " << FUNC_ID << " : This function will print hello china." << endl;}virtual int GetID(void){return FUNC_ID;}};extern "C" void CreateObj(IPrintPlugin **ppPlugin){static CPrintPlugin plugin;*ppPlugin = &plugin;}Main.cpp#include <iostream>#include "CPluginController.h"#include <string.h>#include <stdlib.h>int main(int argc, char **argv){if(argc != 2){cout << "Parameters error" << endl;return 0;}if(strcmp(argv[1], "help") == 0){CPluginController pc;pc.ProcessHelp();return 0;}int FunctionID = atoi(argv[1]);CPluginController pc;pc.InitializeController();pc.ProcessRequest(FunctionID);pc.UninitializeController();return 0;}程序运行结果如图4所示：图4：插件获取类对象综合练习：CPluginController.cpp#include "CPluginController.h"#include "CPluginEnumerator.h"#include "IPrintPlugin.h"#include "dlfcn.h"#include <string.h>CPluginController::CPluginController(void){}CPluginController::~CPluginController(void){}bool CPluginController::InitializeController(void){std::vector<std::string> vstrPluginNames;CPluginEnumerator enumerator;if(!enumerator.GetPluginNames(vstrPluginNames))return false;for(unsigned int i=0 ; i<vstrPluginNames.size(); i++){typedef int (*PLUGIN_CREATE)(IPrintPlugin**);PLUGIN_CREATE CreateProc;IPrintPlugin *pPlugin = NULL;void* hinstLib = dlopen(vstrPluginNames[i].c_str(), RTLD_LAZY);if(hinstLib != NULL){m_vhForPlugin.push_back(hinstLib);CreateProc = (PLUGIN_CREATE)dlsym(hinstLib, "CreateObj");if(NULL != CreateProc){(CreateProc)(&pPlugin);if(pPlugin != NULL){m_vpPlugin.push_back(pPlugin);}}}}return true;}bool CPluginController::ProcessRequest(int FunctionID){for(unsigned int i = 0; i < m_vpPlugin.size(); i++){if(m_vpPlugin[i]->GetID() == FunctionID){m_vpPlugin[i]->Print();break;}}return true;}bool CPluginController::ProcessHelp(void){std::vector<std::string> vstrPluginNames;CPluginEnumerator enumerator;if(!enumerator.GetPluginNames(vstrPluginNames))return false;for(unsigned int i=0 ; i<vstrPluginNames.size(); i++){typedef int (*PLUGIN_CREATE)(IPrintPlugin**);PLUGIN_CREATE CreateProc;IPrintPlugin *pPlugin = NULL;void* hinstLib = dlopen(vstrPluginNames[i].c_str(), RTLD_LAZY);if(hinstLib != NULL){CreateProc = (PLUGIN_CREATE)dlsym(hinstLib, "CreateObj");if(NULL != CreateProc){(CreateProc)(&pPlugin);if(pPlugin != NULL){pPlugin->Help();}}dlclose(hinstLib);}}return true;}bool CPluginController::IfProcess(char *Function)//判断插件是否存在{unsigned int i;for(i = 0; i < m_vpPlugin.size(); i++){if(strcmp(Function, m_vpPlugin[i]->GetName()) == 0){break;}};if(i < m_vpPlugin.size())//插件存在{return true;}else{return false;}}bool CPluginController::ProcessFunction(char *Function,char*Document)//执行插件功能for(unsigned int i = 0; i < m_vpPlugin.size(); i++){if(strcmp(Function, m_vpPlugin[i]->GetName()) == 0){m_vpPlugin[i]->Fun(Document);//插件功能break;}}return true;}bool CPluginController::UninitializeController(){for(unsigned int i = 0; i < m_vhForPlugin.size(); i++){dlclose(m_vhForPlugin[i]);}return true;}CPluginController.h#ifndef CPLUGINCONTROLLER_H#define CPLUGINCONTROLLER_H#include <vector>class IPrintPlugin;class CPluginController{public:CPluginController(void);virtual ~CPluginController(void);bool InitializeController(void);bool UninitializeController(void);bool ProcessHelp(void);bool ProcessRequest(int FunctionID);bool IfProcess(char *Function);bool ProcessFunction(char *Function,char *Document);private:std::vector<void *> m_vhForPlugin;std::vector<IPrintPlugin*> m_vpPlugin;};#endifCPluginEnumerator.h#ifndef CPLUGINENUMERATOR_H#define CPLUGINENUMERATOR_H#include <vector>#include <string>using namespace std;class CPluginEnumerator{public:CPluginEnumerator();virtual ~CPluginEnumerator();bool GetPluginNames(vector<string>& vstrPluginNames);};#endifCPluginEnumerator.cpp#include "CPluginEnumerator.h"#include <dirent.h>#include <string.h>CPluginEnumerator::CPluginEnumerator(){}CPluginEnumerator::~CPluginEnumerator(){}bool CPluginEnumerator::GetPluginNames(vector<string>& vstrPluginNames) {DIR *dir = opendir("./plugin");if(dir == 0)return false;for(;;){struct dirent *pentry = readdir(dir);if(pentry == 0)break;if(strcmp(pentry->d_name, ".") == 0)continue;if(strcmp(pentry->d_name, "..") == 0)continue;string str = "./plugin/";str += pentry->d_name;vstrPluginNames.push_back(str);}closedir(dir);return true;}Main.cpp#include <iostream>#include "CPluginController.h"#include <string.h>#include <stdlib.h>using namespace std;int main(int argc, char **argv){if(argc == 2){if(strcmp(argv[1], "help") == 0)//帮助功能{CPluginController pc;pc.ProcessHelp();return 0;}else{int FunctionID = atoi(argv[1]);CPluginController pc;pc.InitializeController();pc.ProcessRequest(FunctionID);pc.UninitializeController();return 0;}}else if(argc == 3){CPluginController pc;char *Function = argv[1];// Function+=".so";char *Document = argv[2];//操作的文件名pc.InitializeController();if(pc.IfProcess(Function)==false)//判断插件是否存在{cout << "No this plugin!" << endl;}else//{pc.ProcessFunction(Function,Document);};pc.UninitializeController();return 0;}else{cout << "Parameters error" << endl;return 0;}}插件：IPrintPlugin.cpp#include "IPrintPlugin.h"IPrintPlugin::IPrintPlugin(){}IPrintPlugin::~IPrintPlugin(){}IPrintPlugin.h#pragma onceclass IPrintPlugin{public:IPrintPlugin();virtual ~IPrintPlugin();virtual void Help() = 0;virtual void Print() = 0;virtual int GetID() = 0;virtual char * GetName() = 0;//添加部分virtual void Fun(char*) = 0;};Line.cpp#include <iostream>#include "IPrintPlugin.h"#include <unistd.h>//read(file)#include <fcntl.h>#include <string.h>using namespace std;const int FUNC_ID = 3;char FUNC_NAME[]="sl";//statistics line! class CPrintPlugin : public IPrintPlugin {public:CPrintPlugin(){}virtual ~CPrintPlugin()}virtual void Print(){cout << "Statistics the document line!" << endl;}virtual void Help(){cout << "Function ID " << FUNC_ID << " : This function will statistics the document line." << endl;}virtual int GetID(void){return FUNC_ID;}virtual char *GetName(){return FUNC_NAME;}virtual void Fun(char *Document){int fp;char temp;long num=0;//统计//open fileif((fp=open(Document,O_RDONLY))==-1){cout<<"Can not open: "<<Document<<endl;return ;};while(read(fp,&temp,1)){if(temp=='\n'){num++;}};close(fp);cout<<Document<<" lines is :"<<num<<endl;};extern "C" void CreateObj(IPrintPlugin **ppPlugin){static CPrintPlugin plugin;*ppPlugin = &plugin;}Words.cpp#include <iostream>#include "IPrintPlugin.h"#include <unistd.h>//read(file)#include <fcntl.h>using namespace std;const int FUNC_ID = 4;char FUNC_NAME[]="sw";//statistics wordsclass CPrintPlugin : public IPrintPlugin{public:CPrintPlugin(){}virtual ~CPrintPlugin(){}virtual void Print(){cout << "statistics the document words!" << endl;}virtual void Help(){cout << "Function ID " << FUNC_ID << " : This function will statistics the document words." << endl;}virtual int GetID(void)return FUNC_ID;}virtual char *GetName(){return FUNC_NAME;}virtual void Fun(char *Document){int fp;char temp;long num=0;//统计//open fileif((fp=open(Document,O_RDONLY))==-1){cout<<"Can not open: "<<Document<<endl;return ;};while(read(fp,&temp,1)){num++;};close(fp);if(num==0){cout<<"Empty file: "<<Document<<endl;return ;};cout<<Document<<"words is :"<<num<<endl;};};extern "C" void CreateObj(IPrintPlugin **ppPlugin) {static CPrintPlugin plugin;*ppPlugin = &plugin;}程序运行结果如图5所示：图5：插件获取类对象七、总结及心得体会：本次试验了解并大致掌握了linux下插件开发的多种方法，尤其是综合试验中，对于插件的安装。