连接池优化

电玩女神 2022-08-09 01:54 199阅读 0赞

package cn.itcast.jdbc.dataSource;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    import java.util.LinkedList;
    
    public class MyDataSource { 
    
        private static String url = "jdbc:mysql://localhost:3306/jdbc";
        private static String user = "root";
        private static String password = "123456";
    
        private static int initCount=5;
        private static int maxCount=10;     //最大连接数，避免创建太多连接影响效率
        private int currentCount=0;
    
    
        public static void main(String[] args) {
    
        }
    
        private LinkedList<Connection> connectionPool = new LinkedList<Connection>(); // 连接池
    
        public MyDataSource() {
    
            try {
                for (int i = 0; i < initCount; i++) { // MyDataSource创建时就建立5个连接
                    this.connectionPool.addLast(this.createConnection());
                    this.currentCount++;
                }
            } catch (SQLException e) {
                throw new ExceptionInInitializerError();
            }
        }
    
        public Connection getConnection() throws SQLException {
            synchronized (connectionPool) { // 确保多个线程不会取到同一个连接
                if (this.connectionPool.size() > 0)
                    return this.connectionPool.removeFirst();
                if(this.currentCount<maxCount){     //当当前连接数小于最大连接数，创建新连接
                    this.currentCount++;
                    return this.createConnection();
                }
                throw new SQLException("已经没有可用连接");
            }
    
    
        }
    
        public void free(Connection conn) { // 释放连接，实际上就是重新加入到连接池
            this.connectionPool.addLast(conn);
        }
    
        private Connection createConnection() throws SQLException {
            return DriverManager.getConnection(url, user, password);
        }
    }