背景

该文档主要是Electron-vue项目的背景下，记录ref-array-napi、ref-napi、ref-struct-napi、ffi-napi 使用基本类型组合类型调用Dll接口 。

基础准备

package.json中

"dependencies "：{"ref-array-napi": "^1.2.0","ref-napi": "^1.4.3","ref-struct-napi": "^1.1.0","ffi-napi": "^2.4.7",
}

简单解释下：ref-napi 主要是一些基本类型需要。ref-array-napi 数组类型需要，ref-struct-napi 结构体类型需要，ffi-napi 连接了C代码和JS代码的核心。

Dll有C工程师编写提供，注意区分32位和64位。

方法/变量声明

(1)、C头文件接口：

#define MIN_VERSION_LEN			64				
#define MAX_COM_NUM				100				
#define MAX_COM_NAME_LEN		64				
#define MAX_COM_INFO_LEN		128					/* unit: byte, max COM info length */
#define MAX_NORMAL_LEN			128					/* unit: byte, max common buffer length */
#define MAX_ID_LEN				64		
#define MAX_IMEI_LEN			16					/* unit: byte, max IMEI length */        #define MAX_CERT_LEN			2048				/* unit: byte, max CERT length, hexstring length with '\0' */
#define MAX_KEY_LEN				2048				/* unit: byte, max KEY length, hexstring length with '\0' */
#define MAX_REFERENCE_ID_LEN	33					/* unit: byte, hexstring length with '\0' */typedef enum CERT_FORMAT {CERT_FORMAT_PKCS12_IN_PEM	= 1,				/* PKCS12 key store which stored all certs and all keys, PEM format file *//* only PKCS12 in PEM format now */
} cert_format_e;typedef struct COM_INFO {char			name[MAX_COM_NAME_LEN];			/* e.g. COMn */char			friendly_name[MAX_COM_INFO_LEN];/* Friendly name with more information for this COM */char			description[MAX_COM_INFO_LEN];	/* Description for this COM */} com_info_t;typedef struct ERROR {int				flag;							/* value 1 means error code is active (error occurred), or for dis-active */char			error_code[MAX_NORMAL_LEN];		/* error code defined in nuSIM */char			error_msg[MAX_NORMAL_LEN];		/* error message for error code */} error_t;typedef struct AS_INFO {char			id[MAX_ID_LEN];				/* ID information */
} info_t;typedef struct FILE_INFO {char			id[MAX_ID_LEN];			error_t		     error;							/* record error msg */char			file[MAX_KEY_LEN];		/* file buffer (hex string format) */} file_info_t;typedef struct FILE_REQUEST_IN {int				flag;						int				file_num;					/* request file number */info_t*		    info;						
} file_request_in_t;typedef struct FILE_REQUEST_OUT {char			reference_id[MAX_REFERENCE_ID_LEN];	/* store buffer for reference_id */
} file_request_out_t;// 返回版本号WIN_DLL_API_EXPORT int VER_get(char* version, int size);// 配置日志路径WIN_DLL_API_EXPORT int LOG_config(const char* log_file, log_level_e log_level);// 获取端口列表WIN_DLL_API_EXPORT int COM_enum(com_info_t* info, int* com_num);//打开端口WIN_DLL_API_EXPORT int COM_open(const char* com_name, int baudrate, int* handle);//发送ATWIN_DLL_API_EXPORT int COM_send_recv(int handle, const char* send, char* recv, int* recv_len, int timeout);// 关闭端口WIN_DLL_API_EXPORT int COM_close(int handle);// 获取IMEIWIN_DLL_API_EXPORT int get_imei(int handle, char* imei, int size);// 初始化设备WIN_DLL_API_EXPORT int init(int handle, const char* cert);// 下载文件WIN_DLL_API_EXPORT int  request_files(const file_request_in_t* in, file_request_out_t* out);// 更新设备文件WIN_DLL_API_EXPORT int update_file(int handle, const file_info_t* info);// 配置HttpsWIN_DLL_API_EXPORT int config_tls_certs(const char* cert_file, const char* password, cert_format_e cert_format);

(2)、NodeJs使用ffi-napi 变量、方法声明

const MAX_ID_NORMAL = 64;
const MAX_COM_NUM = 100;
const MAX_COM_NAME_LEN = 64;
const MAX_COM_INFO_LEN = 128;
const MAX_CERT_LEN = 2048;
const MAX_NORMAL_LEN = 128;
const MAX_IMEI_LEN = 16;
const MAX_RECV_AT = 1024;
const MAX_REFERENCE_ID_LEN = 33;var AsInfo = refStruct({id: new ArrayType(ref.types.char, MAX_ID_NORMAL )
});
var FILEREQUESTIN = refStruct({id: new ArrayType(ref.types.char, MAX_ID_LEN),file_num: ref.types.int,as_info: AsInfoArrayType,
});var FILEREQUESTOUT = refStruct({reference_id: new ArrayType(ref.types.char, MAX_REFERENCE_ID_LEN),
});const CERT_FORMAT = {CERT_FORMAT_PKCS12_IN_PEM: 1,
};
var ERROR = refStruct({flag: ref.types.int,error_code: ArrayType(ref.types.char, MAX_NORMAL_LEN),error_msg: ArrayType(ref.types.char, MAX_NORMAL_LEN),
});
var ComInfo = refStruct({name: ArrayType(ref.types.char, MAX_COM_NAME_LEN), //名称friendly_name: ArrayType(ref.types.char, MAX_COM_INFO_LEN), //全称description: ArrayType(ref.types.char, MAX_COM_INFO_LEN), // 描述
});var fileInfo = refStruct({id: ArrayType(ref.types.char, MAX_ID_LEN),error: ERROR,file: ArrayType(ref.types.char, MAX_KEY_LEN),
});class DeviceInfo {constructor(commName, handlePtr,initData, file, imei) {this.commName = commName;this.handlePtr = handlePtr;this.file = file;this.initData= initData;this.imei = imei;}
}//端口数组A
var ComInfoArrayType = ArrayType(ComInfo);
var AsInfoArrayType = ArrayType(AsInfo);
var fileInfoArray = ArrayType(fileInfo);
// 设备列表
var devicesArray = new Array();const dllLib = ffi.Library(libpath, {LOG_config: ['int', ['string', 'int']],VER_get: [ref.types.int, ['string', ref.types.int]],COM_enum: [ref.types.int, [ComInfoArrayType, 'int *']],COM_open: [ref.types.int, ['string', ref.types.int, 'int *']],COM_close: [ref.types.int, [ref.types.int]],check_connected: [ref.types.int, [ref.types.int]],get_imei: [ref.types.int, [ref.types.int, 'string', ref.types.int]],init: [ref.types.int, [ref.types.int, 'string']],request_files: [ref.types.int, [ref.refType(FILEREQUESTIN), ref.refType(FILEREQUESTOUT)]],update_file: [ref.types.int, [ref.types.int, ref.refType(fileInfo)]],send_recv: [ref.types.int, [ref.types.int, 'string', 'string', 'int *', ref.types.int]],
});

(3)、NodeJs方法实现

const dllModule = {getVersion: function() {var version = new Buffer(MAX_NORMAL_LEN);var result = dllLib.VER_get(version, version.length);if (result === 0) {// TODO} else {// TODO}},
// 配置dll 日志存放路径，级别
configLog: function() {var logDllPath = path.join(__dirname, '../../../data/log.txt');var result = dllLib.LA_LOG_config(logDllPath, 5);//TODO},// 得到COM 口信息
getComInfo: function() {var comNumPtr = ref.alloc('int', MAX_COM_NUM); //预先分配int  指针空间 并加入默认值var comInfoArr = ComInfoArrayType(MAX_COM_NUM);var result = dllLib.LA_COM_enum(comInfoArr, comNumPtr);log.info('端口数量: ' + comNumPtr.deref());var comNameArray = new Array(); // 所有的端口for (var i = 0; i < comNumPtr.deref(); i++) {var name = ref.readCString(Buffer.from(comInfoArr[i].name));comNameArray.push(name);}
},/*** 发送AT接口* @param {*} item 设备对象* @param {*} command AT命令*/
sendAT: function(item, command) {// 加上结束符command = command + "\r\n";var receiveLen = ref.alloc('int', MAX_RECV_AT); //预先分配int  指针空间var recvBuf = new Buffer(MAX_RECV_AT);// 异步dllLib.send_recv.async(item.handlePtr.deref(), command, recvBuf, receiveLen, 10, (err, result) => {var rec = ref.readCString(recvBuf);//读取字符串， 这样能去除多余字符if (result == 0) {// TODO} else {// TODO}});},// 检查连接状态
checkConnect: function(item) {dllLib.check_connected.async(item.handlePtr.deref(), (err, result) => {// TODO});},openPort:function(item){dllLib.COM_open.async(item.commName, mBadurate, item.handlePtr, (err, result) => {if (result == 0) {// 再次检查连接DllHandle.checkConnect(item);} else {//TODO}});
},// 关闭端口
closePort: function(item) {var result = dllLib.COM_close.async(item.handlePtr.deref(), (err, result) => {//TODO});},
// 获取设备IMEI
getImei: function(item) {var imeiBuf = new Buffer(MAX_IMEI_LEN);dllLib.LA_DEV_get_imei.async(item.handlePtr.deref(), imeiBuf, imeiBuf.length, (err, result) => {item.imei = ref.readCString(imeiBuf);if (result == 0) {//TODO} else {//TODO}});},
// 请求files 
requestFile:function(data){var asinFoList = new Array(); // 结构体列表
for (i; i < count; i++) {var idBuf = Buffer.from(data[i].id);var entity = new AsInfo();entity.id = Array.prototype.slice.call(idBuf, 0);// 转化成数组，需要这样用asinFoList.push(entity);}var requestIn = new FILEREQUESTIN();// 构造结构体requestIn.id = Array.prototype.slice.call("xxxx", 0);requestIn.file_num = asinFoList.length;requestIn.as_info = asinFoList; // 赋值结构体列表var requestOut = new FILEREQUESTOUT(); // 构造结构体requestOut.reference_id_size = MAX_ID_LEN;// 异步调用CdllLib.request_files.async(requestIn.ref(), requestOut.ref(), (err, result) => {if (result == 0) {// TODO}else{//TODO}});},init:function(item){var buf = Buffer.from(item.initData);dllLib.init.async(item.handlePtr.deref(), buf, (err, result) => {if(result ==0){//TODO}}
},
updateFile:function(item,data){var fileEntity = new fileInfo();var idBuf = Buffer.from(data.id);var fileBuf = Buffer.from(data.file);fileEntity.id = Array.prototype.slice.call(idBuf, 0);fileEntity.file = Array.prototype.slice.call(fileBuf, 0);dllLib.update_file.async(item.handlePtr.deref(),fileEntity .ref(),(err, result) => {// TODO}}
};

Tips: async关键字就是异步的功效需要传入回调函数，如果没有就是同步执行，C实现接口可以不用支持异步回调，

结尾

代码包含C的接口，变量的声明，对应Js变量、方法的声明和实现.具体语法使用代码中体现