C语言智能家居服务器：数据库查询并生成建议

#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[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;
} 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\n');
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;
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;
memset(&status, 0, sizeof(Status)); // 清空status结构体
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)-1);
    strncpy(status.device_state, sqlite3_column_text(stmt, 3), sizeof(status.device_state)-1);
    strncpy(status.value, sqlite3_column_text(stmt, 4), sizeof(status.value)-1);
    strncpy(status.mode, sqlite3_column_text(stmt, 5), sizeof(status.mode)-1);
}
    if (rc == SQLITE_DONE) {
    fprintf(stderr, 'No data found for user %d\n', userid);

    sqlite3_finalize(stmt);
    }
int columnCount = sqlite3_column_count(stmt);
  printf('列数：%d\n', columnCount);
if (sqlite3_column_count(stmt) == 0) {
      fprintf(stderr, '查询结果为空\n');
      return;
  }
sqlite3_finalize(stmt);

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\nsend');
    return;
}
printf('%s',suggestion);

}

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;

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\naccept');
            break;
        }

        context.sockfd = clientSockfd;
        handleClientRequest(&context);

        close(clientSockfd);
    }
}
sqlite3_close(db);
close(sockfd);
printf('服务器已关闭\n');

return 0;

}

下面是客户端的代码 #include 'procession.h' #include 'ui_procession.h' #include #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(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, QOverloadQAbstractSocket::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'); QByteArray block; QDataStream out(&block, QIODevice::WriteOnly); out << static_cast(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 qDebug()<<'1'; }

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()));

}

#ifndef PROCESSION_H #define PROCESSION_H

#include #include #include #include #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 on_pushButton_clicked(); 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

root@WIN-K3C9KG85CB8:/home/SmartHome/Server# valgrind --leak-check=full ./main.exec ==2651== Memcheck, a memory error detector ==2651== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==2651== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info ==2651== Command: ./main.exec ==2651== 正在连接中... 客户端已连接 ==2651== Invalid read of size 1 ==2651== at 0x484EFFF: strncpy (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so) ==2651== by 0x10978C: handleClientRequest (in /home/SmartHome/Server/main.exec) ==2651== by 0x109D4F: main (in /home/SmartHome/Server/main.exec) ==2651== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==2651== ==2651== ==2651== Process terminating with default action of signal 11 (SIGSEGV) ==2651== Access not within mapped region at address 0x0 ==2651== at 0x484EFFF: strncpy (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so) ==2651== by 0x10978C: handleClientRequest (in /home/SmartHome/Server/main.exec) ==2651== by 0x109D4F: main (in /home/SmartHome/Server/main.exec) ==2651== If you believe this happened as a result of a stack ==2651== overflow in your program's main thread (unlikely but ==2651== possible), you can try to increase the size of the ==2651== main thread stack using the --main-stacksize= flag. ==2651== The main thread stack size used in this run was 8388608. ==2651== ==2651== HEAP SUMMARY: ==2651== in use at exit: 111,752 bytes in 220 blocks ==2651== total heap usage: 344 allocs, 124 frees, 142,600 bytes allocated ==2651== ==2651== LEAK SUMMARY: ==2651== definitely lost: 0 bytes in 0 blocks ==2651== indirectly lost: 0 bytes in 0 blocks ==2651== possibly lost: 0 bytes in 0 blocks ==2651== still reachable: 111,752 bytes in 220 blocks ==2651== of which reachable via heuristic: ==2651== length64 : 110,728 bytes in 219 blocks ==2651== suppressed: 0 bytes in 0 blocks ==2651== Reachable blocks (those to which a pointer was found) are not shown. ==2651== To see them, rerun with: --leak-check=full --show-leak-kinds=all ==2651== ==2651== For lists of detected and suppressed errors, rerun with: -s ==2651== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0) Segmentation fault 这是怎么回事内容：在函数handleClientRequest中，当查询结果为空时，没有正确处理，导致后续操作出现问题。在查询结果为空时，应该直接返回。可以将以下代码块移动到查询结束后进行判断和处理：

if (sqlite3_column_count(stmt) == 0) {
    fprintf(stderr, '查询结果为空\n');
    return;
}

另外，还需要检查sqlite3_prepare_v2、sqlite3_step等函数的返回值，确保数据库操作没有出错。