jdbc连接池配置方法

代码：import java.io.FileInputStream;import java.io.FileNotFoundException;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.LinkedList;
import java.util.Properties;

import org.slf4j.Logger;

public class ConnPool {
    // 使用LinkedList集合存放数据库连接
    private static LinkedList<Connection> connPool = new LinkedList<Connection>();

    // 在静态代码块中加载配置文件
    static {
　　　　　//如果以jar包运行，此处会报找不到这个文件的异常，解决方案如下。
        String path = ConnPool.class.getClassLoader().getResource("db.properties").getPath();//解决方案需要注释这行代码
　　　　　//InputStream in = PropertiesUtil.class.getClassLoader.getResourceAsStream("db.properties");//开启这行代码解决以上问题

        FileInputStream in;//开启以上解决方案需要注释调这行代码
        try {
            in = new FileInputStream(path);//开启以上解决方案需要注释这行代码
            Properties prop = new Properties();
            prop.load(in);
            String driver = prop.getProperty("driver");
            String url = prop.getProperty("url");
            String user = prop.getProperty("user");
            String password = prop.getProperty("password");
            // 数据库连接池的初始化连接数的大小
            int InitSize = Integer.parseInt(prop.getProperty("InitSize"));
            // 加载驱动
            Class.forName(driver);
            for (int i = 0; i < InitSize; i++) {
                Connection conn = DriverManager.getConnection(url, user, password);
                // 将创建的连接添加的list中
                System.out.println("初始化数据库连接池，创建第 " + (i + 1) + " 个连接，添加到池中");
                connPool.add(conn);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    /*获取数据库连接*/
    public Connection getConnection() throws SQLException {
        if(connPool.size() > 0){
            //从集合中获取一个连接
            final Connection conn = connPool.removeFirst(); 
            //返回Connection的代理对象
            return (Connection) Proxy.newProxyInstance(ConnPool.class.getClassLoader(), conn.getClass().getInterfaces(), new InvocationHandler() {
                public Object invoke(Object proxy, Method method, Object[] args)
                        throws Throwable {
                    if(!"close".equals(method.getName())){
                        return method.invoke(conn, args);
                    }else{
                        connPool.add(conn);
                        System.out.println("关闭当前连接，把连接还给连接池.........");
                        System.out.println("池中连接数为 " + connPool.size());
                        return null;
                    }
                }
            });
        }else{
            throw new RuntimeException("数据库繁忙，稍后再试............");
        }
    }

    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }

    public void setLogWriter(PrintWriter out) throws SQLException {

    }

    public void setLoginTimeout(int seconds) throws SQLException {

    }

    public int getLoginTimeout() throws SQLException {
        return 0;
    }

    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }

    public Object unwrap(Class iface) throws SQLException {
        return null;
    }

    public boolean isWrapperFor(Class iface) throws SQLException {
        return false;
    }

    public Connection getConnection(String username, String password)
            throws SQLException {
        return null;
    }
}

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JdbcUtil {

    //数据库连接池
    private static ConnPool  connPool = new ConnPool();

    /**
     * 从池中获取一个连接
     * @return
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException{
        return connPool.getConnection();
    }

    /**
     * 关闭连接
     * @param conn
     * @param st
     * @param rs
     * @throws SQLException 
     */
    public static void CloseConnection(Connection conn, Statement st, ResultSet rs) throws SQLException{

        // 关闭存储查询结果的ResultSet对象
        if(rs != null){
                rs.close();
        }

        //关闭Statement对象
        if(st != null){
                st.close();
        }

        //关闭连接
        if(conn != null){
                conn.close();
        }
    }

}

db.properties

driver = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/数据库名?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf8&useSSL=TRUE
user = root
password = root
InitSize = 15

调用如下：

JdbcUtil jdbcUtil = new JdbcUtil();

　　String sql = "要写的SQL语句";
　　Connection connection = null;
　　Statement statement = null;
　　ResultSet resultSet = null;

try{
　　connection = jdbcUtil.getConnection();
　　statement = connection.createStatement();
　　resultSet = statement.executeQuery(sql);
　　　　while (resultSet.next()) {
    　　　　String id= resultSet.getString("id");
    　　　　if (id!= null) {
　　　　　　//可以在这里写业务逻辑
　　　　　　}
　　　　}
　　} catch (Exception e) {
            logger.error("数据获取失败", e);
            msg = createResultJson(1, "数据获取失败！");
   } finally {
     try {
       　　jdbcUtil.CloseConnection(connection, statement, resultSet);//最后记得关闭流，不然会报创建连接过多的异常
     } catch (SQLException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
     }
   }