Java自定义jdbc连接池

获取连接工具类：

package com.itest;

import java.sql.*;

public class JdbcUtils {
    //获得连接
    public static Connection getConnection() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/gjp","root", "123");
        return con;
    }
    //关闭连接
    public static void closeResource(Connection con, Statement st, ResultSet rs){
        closeResultSet(rs);
        closeStatement(st);
        closeConnection(con);
    }

    public static void closeConnection(Connection con){
        if (con != null){
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }

            con = null;
        }
    }

    public static void closeStatement(Statement st){
        if (st != null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }

            st = null;
        }
    }

    public static void closeResultSet(ResultSet rs){
        if (rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }

            rs = null;
        }
    }
}

自定义连接池：

package com.itest;

import java.sql.Connection;
import java.util.LinkedList;

public class MydataSource {
    static LinkedList pool = new LinkedList<>();

    //初始化连接池
    static {
        for (int i = 0; i < 3; i++) {
            try {
                Connection conn = JdbcUtils.getConnection();
                pool.addLast(conn);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    //获取链接
    public static Connection getConnection(){
        if (pool == null) {
            for (int i = 0; i < 3; i++) {
                try {
                    Connection conn = JdbcUtils.getConnection();
                    pool.addLast(conn);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        System.out.println("从连接池中获取连接");
        return pool.removeFirst();
    }

    public static void addBack(Connection connection){
        pool.addLast(connection);
        System.out.println("连接已归还到池中");
    }
}

测试类：

package com.itest;

import java.sql.Connection;

public class test {
    public static void main(String[] args) {
        MydataSource ds = new MydataSource();

        Connection conn = ds.getConnection();

        System.out.println(conn);

        ds.addBack(conn);
    }
}