Qt中QHostInfo::lookupHost()函数的方法示例

static void lookupHost(
    const QString &host,          // 主机名/IP字符串
    QObject *receiver,            // 接收结果的QObject派生类对象
    const char *member            // receiver的槽函数/成员函数（需接受QHostInfo参数）
);

static LookupHost *lookupHost(
    const QString &host,          // 主机名/IP字符串
    QObject *receiver,            // 接收结果的QObject
    const char *member            // 回调槽函数
);
// 或简化为：
static LookupHost *lookupHost(const QString &host, QObject *receiver, PointerToMemberFunction member);

// 正确的槽函数声明
void MyWidget::onLookupFinished(const QHostInfo &hostInfo);

// 头文件
#include <QHostInfo>
#include <QDebug>
#include <QTcpSocket>
 
class StreamMonitor : public QWidget {
    Q_OBJECT
public:
    StreamMonitor(QWidget *parent = nullptr) : QWidget(parent) {
        // 假设有一个按钮触发查询
        connect(&m_lookupButton, &QPushButton::clicked, this, &StreamMonitor::lookupServer);
    }
 
private slots:
    void lookupServer() {
        QString serverHost = "stream.example.com"; // 流媒体服务器域名
        // 异步查询，回调到onLookupFinished
        QHostInfo::lookupHost(serverHost, this, &StreamMonitor::onLookupFinished);
    }
 
    void onLookupFinished(const QHostInfo &hostInfo) {
        // 1. 错误处理
        if (hostInfo.error() != QHostInfo::NoError) {
            qWarning() << "DNS解析失败：" << hostInfo.errorString();
            return;
        }
 
        // 2. 获取IP列表（过滤IPv4，流媒体常用）
        QList<QHostAddress> ips = hostInfo.addresses();
        for (const QHostAddress &ip : ips) {
            if (ip.protocol() == QAbstractSocket::IPv4Protocol) {
                qDebug() << "解析到IPv4地址：" << ip.toString();
                // 尝试连接流媒体服务器（比如RTSP/HTTP）
                m_tcpSocket.connectToHost(ip, 554); // RTSP默认端口554
                break; // 取第一个IPv4地址（可根据需求调整）
            }
        }
    }
 
private:
    QPushButton m_lookupButton;
    QTcpSocket m_tcpSocket;
};

// 发起查询并保存LookupHost对象
QHostInfo::LookupHost *lookup = QHostInfo::lookupHost("stream.example.com", this, &StreamMonitor::onLookupFinished);
 
// 若用户取消输入，可终止查询
lookup->abort(); // 终止后，onLookupFinished仍会被调用，但error()为AbortedError

QPointer<QObject> m_receiver; // 成员变量
void StreamMonitor::lookupServer() {
    m_receiver = this;
    QHostInfo::lookupHost("server.com", m_receiver.data(), &StreamMonitor::onLookupFinished);
}

QHostInfo::setCacheEnabled(false); // 禁用缓存
// 或清除缓存
QHostInfo::clearCache();

for (const QHostAddress &ip : hostInfo.addresses()) {
    if (ip.protocol() == QAbstractSocket::IPv4Protocol) {
        // 处理IPv4
    }
}