HikariPool连接池的使用

测试代码： 使用连接池用时500ms, 不使用连接池用时8s, 相差16倍. 
每个连接的创建都要经过http握手、密码认证，这里比较耗时， mysql给每个connection分配一个id

public class DBpoolTest {

    private static final HikariDataSource ds;

    static {
        HikariConfig conf = new HikariConfig();
        conf.setUsername("root");
        conf.setPassword("root");
        conf.setJdbcUrl("jdbc:mysql://localhost:3306/abc");
        ds = new HikariDataSource(conf);
    }

    @Test
    public void test_1() throws SQLException {
        long st = System.currentTimeMillis();
        for (int i = 0; i < 1000; i++) {
            Connection connection = ds.getConnection();
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery("select now() from dual");
            while (resultSet.next()) {
                System.out.println(resultSet.getString(1));
            }
            connection.close();
        }
        System.out.println(System.currentTimeMillis() - st);
    }

    @Test
    public void test_2() throws SQLException {
        long st = System.currentTimeMillis();
        for (int i = 0; i < 1000; i++) {
            Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/abc", "root", "root");
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery("select now() from dual");
            while (resultSet.next()) {
                System.out.println(resultSet.getString(1));
            }
            connection.close();
        }
        System.out.println(System.currentTimeMillis() - st);
    }
}

　　

连接池回收过程

HikariDataSource datasource= new HikariDataSource( xxxx );

Connection cn = datasource.getConnection();

try {

     cn.doXXX()

} finnally(){

     connection.close();// connection的实现类（代理类）自己会调用hikariPool.evictConnection(cn) ,将此连接回收到pool中

}

connection回收到池中是连接池自己做的事， 业务代码不用关心物理连接是否真的关闭,只需要调用close（）方法

Hikari中connection.close()的实现 

Druid close（）实现