下面是一个简单的C++代码示例，展示如何使用连接池来连接和操作MySQL数据库。在编译和运行之前，请确保已经安装了MySQL C++ Connector。
#include <mysql_driver.h>#include <mysql_connection.h>#include <cppconn/driver_manager.h>#include <cppconn/exception.h>#include <cppconn/prepared_statement.h>#include <mutex>#include <queue>class ConnectionPool {public:static ConnectionPool& getInstance() {static ConnectionPool instance;return instance;}std::shared_ptr<sql::Connection> getConnection() {std::unique_lock<std::mutex> lock(mutex_);if (connections_.empty()) {return nullptr; // 连接池中无可用连接}auto conn = connections_.front();connections_.pop();return conn;}void releaseConnection(std::shared_ptr<sql::Connection> conn) {std::unique_lock<std::mutex> lock(mutex_);connections_.push(conn);}private:ConnectionPool() : poolSize_(10) {try {sql::mysql::MySQL_Driver* driver;sql::ConnectOptionsMap connection_properties;// 设置连接属性，例如用户名、密码等connection_properties["hostName"] = "localhost";connection_properties["userName"] = "your_username";connection_properties["password"] = "your_password";// 创建驱动程序对象并建立连接driver = sql::mysql::get_mysql_driver_instance();for (int i = 0; i < poolSize_; ++i) {std::shared_ptr<sql::Connection> conn(driver->connect(connection_properties));connections_.push(conn);}} catch (sql::SQLException& e) {// 处理连接异常}}int poolSize_;std::queue<std::shared_ptr<sql::Connection>> connections_;std::mutex mutex_;};int main() {ConnectionPool& pool = ConnectionPool::getInstance();// 获取连接std::shared_ptr<sql::Connection> conn = pool.getConnection();if (conn != nullptr) {try {// 使用连接执行SQL语句等操作std::shared_ptr<sql::Statement> stmt(conn->createStatement());stmt->execute("USE your_database");stmt->execute("SELECT * FROM your_table");while (std::shared_ptr<sql::ResultSet> res(stmt->getResultSet())) {while (res->next()) {// 处理查询结果}res.reset(stmt->getMoreResults() ? stmt->getResultSet() : nullptr);}} catch (sql::SQLException& e) {// 处理数据库操作异常}// 释放连接到连接池中pool.releaseConnection(conn);}return 0;}
要编译和链接这个代码，可以使用以下命令：
g++ -o connection_pool connection_pool.cpp -lmysqlcppconn -std=c++11
确保你的编译环境中已经正确安装了MySQL C++ Connector，并将其链接到你的程序中。然后就可以运行可执行文件 connection_pool 来测试验证连接池功能了。
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