JDBC连接池mini版的实现

首先是工具类 DbUtil

主要参数就是Driver、User、PWD等啦，主要用于建立连接
URL需要注意的是SSL和serverTimezone参数，和mysql驱动版本有关

public class DbUtil {

    private static final String DRIVER = "com.mysql.cj.jdbc.Driver";

    private static final String URL = "jdbc:mysql://127.0.0.1:3306/school?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC";

    private static final String USER = "root";

    private static final String PWD = "123456";

    public static Connection getConnection(){

        try {

            Class.forName(DRIVER);

            Connection conn = (Connection) DriverManager.getConnection(URL,USER,PWD);

            System.out.println("generate a new connection:"+conn.hashCode());

            return conn;

        } catch (Exception e) {

            e.printStackTrace();

            return null;

        }

    }

}

DBPool连接池

设置的一个最大容量为20的连接池
使用静态代码块进行初始化，初始化用到的锁会在后面继续介绍
主要包含三个方法，建立连接、扩充连接池和回收连接



public class DBPool {

    private static final int max = 20;

    private static final int min = 5;

    private static int poolSize = 0;

    private DBPool(){}

    private static ConcurrentLinkedQueue<Connection> pool = new ConcurrentLinkedQueue<Connection>();

    static {

        if (poolSize == 0 && pool.isEmpty()){

            synchronized (DBPool.class){

                if (poolSize == 0 && pool.isEmpty()){

                    try {

                        System.out.println("连接池为空，正在初始化");

                        for (int i = 0; i < min; i++) {

                            pool.add(DbUtil.getConnection());

                            poolSize++;

                        }

                    }catch (Exception e){

                        e.printStackTrace();

                    }

                }

            }

        }

    }

    public static Connection getConnection(){

        try {

            if (!pool.isEmpty()){

                System.out.println("获得连接");

                return pool.remove();

            }else {

                System.out.println("正在扩大连接池");

                dilatation(5);

                System.out.println("正在获得连接");

                while (true){

                    if (!pool.isEmpty()){

                        System.out.println("获得连接");

                        return pool.remove();

                    }

                }

            }

        }catch (Exception e){

            e.printStackTrace();

            return null;

        }

    }

    public static void dilatation(int num){

        if (poolSize > max){

            System.out.println("超过连接池最大数量");

            return;

        }

        for (int i = 0; i < num; i++) {

            pool.add(DbUtil.getConnection());

            poolSize++;

        }

    }

    public static void close(Connection conn){

        pool.add(conn);

        System.out.println("回收成功");

    }

}

JDBCTest测试类



public class JDBCTest {

    public static void main(String[] args) {

        Connection c1 = DBPool.getConnection();

        DBPool.close(c1);

        System.out.println("该连接为："+c1.hashCode());

       for (int i = 0; i < 20; i++) {

            System.out.println("连接"+i+" :"+DBPool.getConnection());

        }

    }

}

巴特西

简易版JDBC连接池

JDBC连接池mini版的实现

首先是工具类 DbUtil

DBPool连接池

JDBCTest测试类

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