UA_Client_readValueAttribute_async封装到类中-Go服务器开发

以下是将UA_Client_readValueAttribute_async封装到类中的示例代码：

#include <open62541/client_config_default.h>
#include <open62541/client_highlevel_async.h>

class MyClient {
public:
    MyClient() {
        client = UA_Client_new();
        config = UA_Client_getDefaultConfig();
        UA_ClientConfig_setDefault(&config);
    }

    ~MyClient() {
        UA_Client_delete(client);
    }

    bool connect(const std::string& url) {
        UA_StatusCode status = UA_Client_connect(client, url.c_str());
        return status == UA_STATUSCODE_GOOD;
    }

    void disconnect() {
        UA_Client_disconnect(client);
    }

    void readValueAsync(const std::string& nodeId, UA_HighLevelCallback callback, void* context) {
        // 构建节点 ID
        const char* nodeIdStr = nodeId.c_str();
        UA_NodeId node = UA_NODEID_STRING(1, nodeIdStr);

        // 读取属性
        const int attributeId = UA_ATTRIBUTEID_VALUE;

        // 异步读取值属性
        const int requestId = 1;  // 可以根据需要自行设置请求 ID
        UA_ReadRequest request;
		UA_ReadRequest_init(&request);
		request.nodesToReadSize = 1;
		request.nodesToRead = (UA_ReadValueId*)UA_Array_new(request.nodesToReadSize, &UA_TYPES[UA_TYPES_READVALUEID]);
		UA_ReadValueId_init(&request.nodesToRead[0]);
		request.nodesToRead[0].nodeId = node;
		request.nodesToRead[0].attributeId = attributeId;

		UA_AsyncOperation asyncOperation;
		asyncOperation.type = UA_ASYNCOPERATIONTYPE_READ;
		asyncOperation.asyncCallback.readCallback.callback = callback;
		asyncOperation.asyncCallback.readCallback.context = context;

        UA_Client_ServiceAsync(client, &request, requestId, &asyncOperation);
    }

private:
    UA_Client* client;
    UA_ClientConfig config;
};

// 示例回调函数
void readValueCallback(UA_Client* client, UA_UInt32 requestId, UA_DataValue* response, void* context) {
    // 处理异步读取结果
}

int main() {
    MyClient client;

    // 连接到 OPC UA 服务器
    std::string serverUrl = "opc.tcp://localhost:4840";
    if (client.connect(serverUrl)) {
        // 异步读取节点值属性
        std::string nodeId = "ns=2;s=MyNode";
        client.readValueAsync(nodeId, readValueCallback, nullptr);

        // 执行其他操作

        // 断开连接
        client.disconnect();
    }

    return 0;
}

这是一个简单的封装示例，你可以根据自己的需要进行修改和扩展。请确保已安装 Open62541 库并链接相关库文件。

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