C/C++网络编程：基于TCP Socket和SQLite数据库的智能家居状态查询系统
C/C++网络编程：基于TCP Socket和SQLite数据库的智能家居状态查询系统
本文将介绍如何使用C/C++语言，结合TCP Socket网络编程和SQLite数据库操作，实现一个简单的智能家居状态查询系统。
1. 系统概述
本系统分为客户端和服务器两部分：
- 服务器端: 监听客户端的连接请求，接收客户端发送的userid，根据userid查询SQLite数据库获取相应的设备状态信息，并根据设备状态信息生成建议，最后将建议发送给客户端。- 客户端: 连接服务器，发送userid，接收服务器返回的建议信息并显示。
2. 代码实现
2.1 服务器端代码c#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/socket.h>#include <sys/select.h>#include <arpa/inet.h>#include <sqlite3.h>#include <netinet/in.h>
#define MAX_BUFFER_SIZE 1024
typedef struct { int uid; char device_name[20]; char device_state[20]; char value[20]; char mode[20];} Status;
typedef struct { int sockfd; struct sockaddr_in client_addr; socklen_t client_addr_len; sqlite3 *db;} ServerContext;
void handleClientRequest(ServerContext *context) { char buffer[MAX_BUFFER_SIZE]; int userid;
// 接收客户端发送的userid ssize_t recvSize = recv(context->sockfd, &userid, sizeof(int), 0);
if (recvSize == -1) { perror('userid接受失败
recv'); return; } else if (recvSize == 0) { perror('客户端已关闭连接'); return; } else if (recvSize != sizeof(int)) { perror('接收到的字节数不正确'); return; } userid = ntohl(userid); // 将网络字节序转换为主机字节序 printf('客户端已连接 '); printf('userid:%d ', userid); // 查询数据库获取设备状态信息 char sql[100]; snprintf(sql, sizeof(sql), 'SELECT * FROM Status WHERE uid = %d', userid); sqlite3_stmt *stmt = NULL; int rc = sqlite3_prepare_v2(context->db, sql, -1, &stmt, NULL); if (rc != SQLITE_OK) { fprintf(stderr, '无法执行的语句: %s ', sqlite3_errmsg(context->db)); return; }
Status status; memset(&status, 0, sizeof(Status)); // 清空status结构体 while (sqlite3_step(stmt) == SQLITE_ROW) { status.uid = sqlite3_column_int(stmt, 1);
const unsigned char *device_name = sqlite3_column_text(stmt, 2); if (device_name != NULL) { strncpy(status.device_name, device_name, sizeof(status.device_name)-1); status.device_name[sizeof(status.device_name)-1] = '�'; }
const unsigned char *device_state = sqlite3_column_text(stmt, 3); if (device_state != NULL) { strncpy(status.device_state, device_state, sizeof(status.device_state)-1); status.device_state[sizeof(status.device_state)-1] = '�'; }
const unsigned char *value = sqlite3_column_text(stmt, 4); if (value != NULL) { strncpy(status.value, value, sizeof(status.value)-1); status.value[sizeof(status.value)-1] = '�'; }
const unsigned char *mode = sqlite3_column_text(stmt, 5); if (mode != NULL) { strncpy(status.mode, mode, sizeof(status.mode)-1); status.mode[sizeof(status.mode)-1] = '�'; } } sqlite3_finalize(stmt); // 释放查询结果集
if (strlen(status.device_name) == 0) { perror('接收设备状态信息失败'); return; }
// 分析设备状态并生成建议 char suggestion[MAX_BUFFER_SIZE]; if (strcmp(status.device_name, '空调') == 0) { int temperature = atoi(status.value); if (temperature < 24) { snprintf(suggestion, sizeof(suggestion), '空调温度过低，建议提高温度至26℃'); } else { snprintf(suggestion, sizeof(suggestion), '空调温度正常'); } } else if (strcmp(status.device_name, '加湿器') == 0) { int humidity = atoi(status.value); if (humidity < 40 || humidity > 70) { snprintf(suggestion, sizeof(suggestion), '加湿器湿度过高或过低，建议调整加湿器湿度'); } else { snprintf(suggestion, sizeof(suggestion), '加湿器湿度正常'); } } else { snprintf(suggestion, sizeof(suggestion), '设备状态未知'); }
// 向客户端发送建议 ssize_t sendSize = send(context->sockfd, suggestion, strlen(suggestion), 0); if (sendSize == -1) { perror('发送失败
send'); return; } else { printf('建议发送成功！'); } printf('%s ', suggestion);}
int main() { printf('正在连接中... '); int sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd == -1) { perror('连接失败 socket'); return 1; }
struct sockaddr_in server_addr; server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = INADDR_ANY; server_addr.sin_port = htons(12345);
if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) { perror('连接失败
bind'); close(sockfd); return 1; }
if (listen(sockfd, 5) == -1) { perror('连接失败
listen'); close(sockfd); return 1; }
sqlite3 *db; int rc = sqlite3_open('/mnt/g/Qt/Client/Smarthome_Client/database/database.db', &db); if (rc != SQLITE_OK) { fprintf(stderr, '数据库打开失败: %s
', sqlite3_errmsg(db)); return 1; }
ServerContext context; context.sockfd = sockfd; context.client_addr_len = sizeof(context.client_addr); context.db = db;
fd_set readfds; int maxfd = sockfd;
while (1) { FD_ZERO(&readfds); FD_SET(sockfd, &readfds);
int activity = select(maxfd + 1, &readfds, NULL, NULL, NULL); if (activity == -1) { perror('select'); break; }
if (FD_ISSET(sockfd, &readfds)) { int clientSockfd = accept(sockfd, (struct sockaddr *)&context.client_addr, &context.client_addr_len); if (clientSockfd == -1) { perror('套接字接收失败
accept'); break; }
context.sockfd = clientSockfd; handleClientRequest(&context);
close(clientSockfd); } } sqlite3_close(db); close(sockfd); printf('服务器已关闭
');
return 0;}
2.2 客户端代码
procession.hcpp#ifndef PROCESSION_H#define PROCESSION_H
#include
namespace Ui {class Procession;}
class Procession : public QWidget{ Q_OBJECT
public: explicit Procession(int userid,QWidget *parent = nullptr); ~Procession(); void processionWidget();
private slots: void connected(); void disconnected(); void readyRead(); void displayError(QAbstractSocket::SocketError error); void on_connectBtn_clicked();
private: Ui::Procession ui; int userid; QTcpSocket m_socket;};
#endif // PROCESSION_H
procession.cppcpp#include 'procession.h'#include 'ui_procession.h'#include
Procession::Procession(int userid,QWidget *parent) : QWidget(parent), ui(new Ui::Procession), userid(userid){ ui->setupUi(this); processionWidget(); m_socket = new QTcpSocket(this); connect(m_socket, &QTcpSocket::readyRead, this, &Procession::readyRead); connect(m_socket, &QTcpSocket::connected, this, &Procession::connected); connect(m_socket, &QTcpSocket::disconnected,this,&Procession::disconnected); connect(m_socket, QOverloadQAbstractSocket::SocketError::of(&QTcpSocket::error), this, &Procession::displayError);}
Procession::~Procession(){ delete ui; m_socket->close();}
void Procession::processionWidget(){ setWindowTitle('服务器通信'); setAutoFillBackground(true); QPalette palette=this->palette(); QPixmap pixmap(':/user/image/image/net.jpg'); palette.setBrush(QPalette::Window, QBrush(pixmap)); setPalette(palette); setFixedSize(600,400);}
void Procession::connected(){ ui->message->append('连接成功'); QByteArray block; QDataStream out(&block, QIODevice::WriteOnly); out << static_cast
void Procession::disconnected(){ ui->message->append('连接已断开'); m_socket->close();}
void Procession::readyRead(){ QByteArray data = m_socket->readAll(); if (data.isEmpty()) { ui->message->append('读取的数据为空'); return; } // 解析服务器返回的数据 QDataStream in(&data, QIODevice::ReadOnly); QString suggestion; in >> suggestion; if (in.status() != QDataStream::Ok) { ui->message->append('解析服务器返回的数据失败'); return; } ui->message->append(suggestion);}
void Procession::displayError(QAbstractSocket::SocketError error){ QString errorMessage; switch (error) { case QAbstractSocket::ConnectionRefusedError: errorMessage = '连接被拒绝'; break; case QAbstractSocket::RemoteHostClosedError: errorMessage = '远程主机关闭'; break; case QAbstractSocket::HostNotFoundError: errorMessage = '未找到主机'; break; case QAbstractSocket::SocketTimeoutError: errorMessage = '连接超时'; break; case QAbstractSocket::NetworkError: errorMessage = '网络错误'; break; default: errorMessage = '未知错误'; break; } ui->message->append('连接失败：' + errorMessage);}
void Procession::on_connectBtn_clicked(){ if (m_socket->state() == QAbstractSocket::ConnectedState) { m_socket->disconnectFromHost(); // 先断开连接 }
QString ip = ui->IP->text(); QString port = ui->port->text();
if (ip.isEmpty() || port.isEmpty()) { ui->message->clear(); ui->message->append('请输入有效的IP地址和端口号'); return; }
ui->message->clear(); ui->message->append('正在连接中...'); m_socket->connectToHost(ip, static_cast<quint16>(ui->port->text().toInt()));}
3. 问题解决
针对代码中出现的问题，进行如下修改：
- 客户端重复连接问题: 在客户端的
connected()函数中，发送完userid后立即关闭连接m_socket->close();。 并在on_connectBtn_clicked()函数中，每次点击按钮时先判断是否已连接，如果已连接则先断开连接。2. 客户端解析数据问题: 检查客户端和服务器端使用的数据类型和大小是否一致。确保使用QDataStream进行数据读写时，操作顺序和类型匹配。
4. 总结
本文介绍了如何使用C/C++实现一个简单的智能家居状态查询系统。系统利用TCP Socket进行网络通信，并使用SQLite数据库进行数据管理。通过该案例，可以学习到基本的网络编程和数据库操作技巧，为开发更加复杂的网络应用程序打下基础
原文地址: http://www.cveoy.top/t/topic/fCDg 著作权归作者所有。请勿转载和采集!