Oracle数据库连接池在C++中的实现

在C++中实现Oracle数据库连接池，可以使用Oracle官方提供的Oracle Call Interface (OCI) 库

1. 首先，确保已经安装了Oracle客户端库和OCI库。可以从Oracle官网下载并安装。

2. 包含必要的头文件：

#include <
    occi.h>
    
#include<
    iostream>
    
#include<
    vector>
    
#include <
    mutex>
    
#include<
    condition_variable>

1. 定义一个连接池类，如下所示：

class OracleConnectionPool {
    
public:
    OracleConnectionPool(const std::string&
     connectionString, const std::string&
     userName, const std::string&
     password, int poolSize);
    
    ~OracleConnectionPool();
    

    oracle::occi::Connection* getConnection();
    
    void releaseConnection(oracle::occi::Connection* connection);
    

private:
    std::vector<
    oracle::occi::Connection*>
     connections_;
    
    std::vector<
    bool>
     connectionStatus_;
    
    std::mutex mutex_;
    
    std::condition_variable cv_;

}
    ;
    

1. 实现连接池类的构造函数、析构函数、获取连接和释放连接的方法：

OracleConnectionPool::OracleConnectionPool(const std::string&
     connectionString, const std::string&
     userName, const std::string&
 password, int poolSize) {
    
    for (int i = 0;
     i<
     poolSize;
 ++i) {
    
        oracle::occi::Environment* env = oracle::occi::Environment::createEnvironment(oracle::occi::Environment::DEFAULT);
    
        oracle::occi::Connection* conn = env->
    createConnection(userName, password, connectionString);
    
        connections_.push_back(conn);
    
        connectionStatus_.push_back(true);

    }

}


OracleConnectionPool::~OracleConnectionPool() {

    for (auto conn : connections_) {
    
        conn->
    close();
    
        oracle::occi::Environment::terminateEnvironment(conn->
    getEnvironment());

    }

}


oracle::occi::Connection* OracleConnectionPool::getConnection() {
    
    std::unique_lock<
    std::mutex>
     lock(mutex_);

    cv_.wait(lock, [this] {
 return std::any_of(connectionStatus_.begin(), connectionStatus_.end(), [](bool status) {
     return status;
 }
    );
 }
    );
    

    auto it = std::find(connectionStatus_.begin(), connectionStatus_.end(), true);
    
    size_t index = std::distance(connectionStatus_.begin(), it);
    
    connectionStatus_[index] = false;
    

    return connections_[index];

}


void OracleConnectionPool::releaseConnection(oracle::occi::Connection* connection) {
    
    std::unique_lock<
    std::mutex>
     lock(mutex_);
    
    auto it = std::find(connections_.begin(), connections_.end(), connection);
    
    size_t index = std::distance(connections_.begin(), it);
    
    connectionStatus_[index] = true;
    
    cv_.notify_one();

}

1. 使用连接池：

int main() {
    
    OracleConnectionPool pool("localhost:1521/XE", "username", "password", 5);
    

    oracle::occi::Connection* conn = pool.getConnection();
    
    oracle::occi::Statement* stmt = conn->
    createStatement("SELECT * FROM your_table");
    
    oracle::occi::ResultSet* rs = stmt->
    executeQuery();
    

    while (rs->
next()) {

        // 处理查询结果
    }
    

    stmt->
    closeResultSet(rs);
    
    conn->
    terminateStatement(stmt);
    
    pool.releaseConnection(conn);
    

    return 0;

}
    

这样就实现了一个简单的Oracle数据库连接池。请注意，这个实现仅作为示例，实际应用中可能需要根据需求进行调整和优化。

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