连接池的简易实现demo

package lyp.basic.dbpool.pool; /** * @ClassName: ConnectionPool * @Author: 键盘国治理专家 * @email: ?????????@qq.com * @Time: 2024/1/21 下午6:59 * @Description: * @Version: 1.0 */ import lyp.basic.dbpool.config.DataSourceConfig; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.TimerTask; import java.util.concurrent.CopyOnWriteArrayList; import java.util.concurrent.atomic.AtomicInteger; /** * @BelongsProject: DataSourcePool * @BelongsPackage: com.bruceliu.pool * @CreateTime: 2020-10-27 23:36 * @Description: TODO */ public class ConnectionPool implements IConnectionPool { // 加载配置类 DataSourceConfig config; // 写一个参数，用来标记当前有多少个活跃的连接, AtomicInteger是线程安全的，见竹花代码一文 private AtomicInteger currentActive = new AtomicInteger(0 ); // 创建一个集合，干嘛的呢？用来存放连接，毕竟我们刚刚初始化的时候就需要创建initSize个连接 // 并且，当我们释放连接的时候，我们就把连接放到这里面 // Vector已经被弃用了，用CopyOnWriteArrayList作为替代 CopyOnWriteArrayList<Connection> freeConns = new CopyOnWriteArrayList<Connection> (); // 正在使用的连接 CopyOnWriteArrayList<ConnEntry> useConns = new CopyOnWriteArrayList<ConnEntry> (); // 构造器中初始化 public ConnectionPool(DataSourceConfig config){ this.config=config; init(); } // 初始化方法 public void init(){ try { // 我们的jdbc是不是每次都要加载呢？肯定不是的，只要加载一次就够了 Class.forName(config.getDriver()); for ( int i = 0; i < Integer.valueOf(config.getInitSize());i++ ){ Connection conn = createConn(); freeConns.add(conn); } } catch (ClassNotFoundException e) { e.printStackTrace(); } //开启任务检查 check(); } // 创建连接 @Override public synchronized Connection createConn(){ Connection conn = null ; try { conn = DriverManager.getConnection(config.getUrl(), config.getUsername(), config.getPassword()); currentActive.incrementAndGet(); System.out.println( "new一个新的连接："+conn); } catch (SQLException e) { e.printStackTrace(); } return conn; } /** * 创建连接有了，是不是也应该获取连接呢？ * @return */ public Connection getConn(){ return getPoolEntry().getConn(); } public synchronized ConnEntry getPoolEntry(){ Connection conn = null ; if (! freeConns.isEmpty()){ conn = freeConns.get(0 ); freeConns.remove( 0 ); } else { if (currentActive.get() < Integer.valueOf(config.getMaxSize())){ conn = createConn(); } else { try { System.out.println( Thread.currentThread().getName() + ",连接池最大连接数为:"+config.getMaxSize()+"已经满了，需要等待..." ); wait( 1000 ); return this.getPoolEntry(); } catch (InterruptedException e) { e.printStackTrace(); } } } ConnEntry connEntry = new ConnEntry(conn, System.currentTimeMillis()); // 获取连接干嘛的？不就是使用的吗？所以，每获取一个，就放入正在使用池中 useConns.add(connEntry); System.out.println(Thread.currentThread().getName() + ",获取并使用连接:"+conn+",空闲线程数："+ freeConns.size()+","+ "再使用线程数:"+ useConns.size()+",总的线程数:"+currentActive.get()); return connEntry; } /** * 创建连接，获取连接都已经有了，接下来就是该释放连接了 */ @Override public synchronized void release(Connection conn){ try { if (!conn.isClosed() && conn != null ){ freeConns.add(conn); } for (int i = 0; i < useConns.size(); i++ ){ if(useConns.get(i).getConn()==conn){ useConns.remove(i); } } System.out.println("回收了一个连接:"+conn+",空闲连接数为:"+ freeConns.size()+",在用线程数为:"+ useConns.size()); notifyAll(); } catch (SQLException e) { e.printStackTrace(); } } // 定时检查占用时间超长的连接，并关闭 private void check(){ if (Boolean.valueOf(config.getHealth())){ Worker worker = new Worker(); new java.util.Timer().schedule(worker, Long.valueOf(config.getDelay()), Long.valueOf(config.getPeriod())); } } class Worker extends TimerTask { //线程类 @Override public void run() { System.out.println( "例行检查..." ); for (int i = 0; i < useConns.size(); i++ ){ ConnEntry entry = useConns.get(i); long startTime = entry.getUseStartTime(); long currentTime = System.currentTimeMillis(); if ((currentTime-startTime)> Long.valueOf(config.getTimeout())){ Connection conn = entry.getConn(); try { if (conn != null && ! conn.isClosed()){ conn.close(); useConns.remove(i); currentActive.decrementAndGet(); System.out.println("发现有超时连接强行关闭,"+conn+",空闲线程数："+ freeConns.size()+","+ "再使用线程数:"+ useConns.size()+",总的线程数:"+currentActive.get()); } } catch (SQLException e) { e.printStackTrace(); } } } } } public DataSourceConfig getConfig() { return config; } public void setConfig(DataSourceConfig config) { this.config = config; } public AtomicInteger getCurrentActive() { return currentActive; } public void setCurrentActive(AtomicInteger currentActive) { this.currentActive = currentActive; } public CopyOnWriteArrayList<Connection> getFreeConns() { return freeConns; } public void setFreeConns(CopyOnWriteArrayList<Connection> freeConns) { this.freeConns = freeConns; } public CopyOnWriteArrayList<ConnEntry> getUseConns() { return useConns; } public void setUseConns(CopyOnWriteArrayList<ConnEntry> useConns) { this.useConns = useConns; } }