JUC的数据库连接池小练习

JUC练习数据库连接池实现

• 通过一个连接数组来充当连接池
• 一个原子的标记数组
• 通过cas来保持多线程下的安全，用synchronized来进行暂停和唤醒

@Slf4j public class MyConnectionPoll {      // 连接池对象数组     private Connection[] connections;     // 使用标记     private AtomicIntegerArray flagArrays;     // 线程池大小     private Integer poolSize;      public MyConnectionPoll(){         this.poolSize = 5;         connections = new MarkConnection[5];         flagArrays = new AtomicIntegerArray(5);         for (int i = 0; i < connections.length; i++) {             connections[i] = new MarkConnection(连接 + i+1);         }     }      // 连接池的初始化     public MyConnectionPoll(int poolSize) {         this.poolSize = poolSize;         connections = new MarkConnection[poolSize];         flagArrays = new AtomicIntegerArray(poolSize);         for (int i = 0; i < connections.length; i++) {             connections[i] = new MarkConnection(连接 + i);         }     }      // 向连接池中请求连接     public Connection getConnection(){         while (true){             for (int i = 0; i < poolSize; i++) {                 // 进行cas请求，如果请求失败就失败                 if (flagArrays.compareAndSet(i,0,1)){                     return connections[i];                 }             }             // 如果请求失败，并且已经没有可用的连接就需要进行等待             synchronized (this){                 try {                     // 等待直到被唤醒，然后对所有请求进行遍历找到空闲连接                     this.wait();  // 调用wait方法需要进行加锁                 } catch (InterruptedException e) {                     e.printStackTrace();                 }             }         }     }      // 释放连接     public void releaseConnection(Connection con){         for (int i = 0; i < poolSize; i++) {             if (con == connections[i]){                 flagArrays.set(i,0);  // 将连接标识置为0即空间连接                 synchronized (this){                     this.notifyAll(); // 唤醒全部等待的线程                 }             }         }     }      public static void main(String[] args) {         MyConnectionPoll myConnectionPoll = new MyConnectionPoll(5);         for (int i = 0; i < 10; i++) {             new Thread(() ->{                 MarkConnection connection =(MarkConnection) myConnectionPoll.getConnection();                 log.debug(获得锁{},connection.getConName());                 try {                     Thread.sleep(1000);                 } catch (InterruptedException e) {                     e.printStackTrace();                 }                 myConnectionPoll.releaseConnection(connection);                 log.debug(释放锁{},connection.getConName());             }).start();         }     } }