智能家居系统：基于SQLite和Socket的设备状态监测与建议生成

该系统包含服务器端和客户端两个部分，服务器端使用SQLite数据库存储设备状态数据，并通过Socket与客户端通信，接收用户ID并返回设备状态建议。客户端通过QTcpSocket连接服务器，发送用户ID并接收状态建议。

服务器端代码

-- 创建用户表
CREATE TABLE IF NOT EXISTS users (
    uid INTEGER PRIMARY KEY AUTOINCREMENT,
    username varchar(10), 
    passwd varchar(10)
);


-- 创建智能家居状态表
CREATE TABLE IF NOT EXISTS Status (
    sid INTEGER PRIMARY KEY AUTOINCREMENT,
    uid INTEGER ,
    device_name varchar(10),
    device_state varchar(10),
    value varchar(10),
    mode varchar(10),
    FOREIGN KEY (uid) REFERENCES users (uid)
);


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sqlite3.h>

#define MAX_BUFFER_SIZE 1024

typedef struct {
    int uid;
    char device_name[10];
    char device_state[10];
    char value[10];
    char mode[10];
} 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\nrecv");
        return;
    }
    printf("客户端已连接\n");

    // 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;
    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\n", sqlite3_errmsg(context->db));
        return;
    }

    Status status;
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        status.uid = sqlite3_column_int(stmt, 1);
        strncpy(status.device_name, sqlite3_column_text(stmt, 2), sizeof(status.device_name));
        strncpy(status.device_state, sqlite3_column_text(stmt, 3), sizeof(status.device_state));
        strncpy(status.value, sqlite3_column_text(stmt, 4), sizeof(status.value));
        strncpy(status.mode, sqlite3_column_text(stmt, 5), sizeof(status.mode));
    }
    sqlite3_finalize(stmt);

    // 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\nsend");
        return;
    }
}

void handleClientConnection(ServerContext *context) {
    int clientSockfd = accept(context->sockfd, (struct sockaddr *)&context->client_addr, &context->client_addr_len);
    if (clientSockfd == -1) {
        perror("套接字接收失败\naccept");
        return;
    }

    ServerContext clientContext;
    clientContext.sockfd = clientSockfd;
    clientContext.client_addr_len = sizeof(clientContext.client_addr);
    clientContext.db = context->db;
    handleClientRequest(&clientContext);

    close(clientSockfd);
}

int main() {
    printf("正在连接中...\n");
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        perror("连接失败\nsocket");
        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\nbind");
        close(sockfd);
        return 1;
    }

    if (listen(sockfd, 5) == -1) {
        perror("连接失败\nlisten");
        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\n", sqlite3_errmsg(db));
        return 1;
    }

    ServerContext context;
    context.sockfd = sockfd;
    context.client_addr_len = sizeof(context.client_addr);
    context.db = db;


    while (1) {
        sleep(1);
        handleClientConnection(&context);
    }

    sqlite3_close(db);
    close(sockfd);
    printf("服务器已关闭\n");

    return 0;
}

#include "procession.h"
#include "ui_procession.h"
#include <QAbstractSocket>
#include <QDebug>

Procession::Procession(int userid,QWidget *parent) : 
    QWidget(parent), 
    ui(new Ui::Procession), 
    userid(userid)
{
    ui->setupUi(this);
    processionWidget();
    m_socket = new QTcpSocket(this);
    connect(ui->connectBtn, &QPushButton::clicked, this, &Procession::on_connectBtn_clicked);
    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, QOverload<QAbstractSocket::SocketError>::of(&QTcpSocket::error), this, &Procession::displayError);
}

Procession::~Procession()
{
    delete ui;
}

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");
    // 发送userid给服务器
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out << this->userid;
    if (m_socket->write(block) == -1) {
        ui->message->append("发送userid失败");
        m_socket->close();
    }
}

void Procession::disconnected()
{
    ui->message->append("连接失败");
    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; // 使用重载的 >> 运算符来读取数据
    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);
    m_socket->close();
}

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(); // 先关闭套接字
        return;
    }
    ui->message->append("已经连接上服务器");
    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()));
}


运行之后服务器显示
“正在连接中...
客户端已连接”
客户端输出QAbstractSocket::connectToHost() called when already looking up or connecting/connected to "127.0.0.1"
客户端GUI界面显示
正在连接中...
连接失败：未知错误
连接成功
解析服务器返回的数据失败
连接失败：远程主机关闭
连接失败
如何解决
叙述代码的逻辑
增加代码使客户端在连接之前处于断开状态，可以在连接按钮点击事件中添加判断，如果套接字的状态为ConnectedState，则先断开连接再进行连接操作。内容：void Procession::on_connectBtn_clicked()
{
    if (m_socket->state() == QAbstractSocket::ConnectedState) {
        m_socket->disconnectFromHost(); // 先关闭套接字
        return;
    }
    ui->message->append("已经连接上服务器");
    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()));
}

客户端代码

#include "procession.h"
#include "ui_procession.h"
#include <QAbstractSocket>
#include <QDebug>

Procession::Procession(int userid,QWidget *parent) : 
    QWidget(parent), 
    ui(new Ui::Procession), 
    userid(userid)
{
    ui->setupUi(this);
    processionWidget();
    m_socket = new QTcpSocket(this);
    connect(ui->connectBtn, &QPushButton::clicked, this, &Procession::on_connectBtn_clicked);
    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, QOverload<QAbstractSocket::SocketError>::of(&QTcpSocket::error), this, &Procession::displayError);
}

Procession::~Procession()
{
    delete ui;
}

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");
    // 发送userid给服务器
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out << this->userid;
    if (m_socket->write(block) == -1) {
        ui->message->append("发送userid失败");
        m_socket->close();
    }
}

void Procession::disconnected()
{
    ui->message->append("连接失败");
    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; // 使用重载的 >> 运算符来读取数据
    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);
    m_socket->close();
}

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(); // 先关闭套接字
        return;
    }
    ui->message->append("已经连接上服务器");
    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()));
}

代码逻辑

服务器端
- 创建用户表和状态表，存储用户信息和设备状态信息
- 使用socket监听端口，等待客户端连接
- 接收客户端发送的用户ID
- 查询数据库获取对应用户ID的设备状态信息
- 分析设备状态信息，生成建议信息
- 将建议信息发送给客户端
客户端
- 连接到服务器
- 发送用户ID给服务器
- 接收服务器返回的建议信息
- 显示建议信息

问题解决

客户端出现“QAbstractSocket::connectToHost() called when already looking up or connecting/connected to "127.0.0.1"”错误，是因为客户端在已经连接到服务器的情况下又尝试连接，导致错误。

解决办法：

在on_connectBtn_clicked()函数中添加判断，如果套接字状态为ConnectedState，则先断开连接再进行连接操作。

代码示例

void Procession::on_connectBtn_clicked()
{
    if (m_socket->state() == QAbstractSocket::ConnectedState) {
        m_socket->disconnectFromHost(); // 先关闭套接字
        return;
    }
    ui->message->append("已经连接上服务器");
    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()));
}

总结

该系统使用SQLite数据库和Socket通信实现了智能家居设备状态监测和建议生成功能，能够根据用户ID和设备状态信息生成相应的建议，提高了智能家居系统的便捷性和智能化水平。