jdbc connection pool configuration

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 {
    //Using the stored set of database connections LinkedList 
    Private  static LinkedList <Connection> = ConnPool new new LinkedList <Connection> (); 

    // loading the configuration file static code block 
    static { 
　　　　　// if the jar package runs reported here will find this abnormal file, the solution is as follows. 
        Path String . = ConnPool class . .GetClassLoader () getResource ( "db.properties" ) .getPath (); // solutions need to comment this line of code
　　　　　// InputStream in = PropertiesUtil.class.getClassLoader.getResourceAsStream ( "db.properties "); // open this line of code to solve the above problem
 
        FileInputStream in; // adjustment programs need to comment this line of code to open more than solve  the try { 
            in = new new FileInputStream (path);// open the above solutions require comment this line of code 
            the Properties prop = new new the Properties (); 
            prop.load (in); 
            String Driver = prop.getProperty ( "Driver" ); 
            String url = prop.getProperty ( "url" ); 
            User String = prop.getProperty ( "User" ); 
            String password = prop.getProperty ( "password" );
             // initialize the database connection pool size number of connections 
            int InitSize = the Integer.parseInt (prop.getProperty ( "InitSize" ) );
             // load drivers 
            Class.forName (driver);
            for (int0 = I; I <InitSize; I ++ ) { 
                Connection Conn = the DriverManager.getConnection (URL, User, password);
                 // add a connection in the list created 
                System.out.println ( "initialize database connection pool, to create the first" + (i + 1) + "connections, added to the pool" ); 
                connPool.add (Conn); 
            } 
        } the catch (IOException E) { 
            e.printStackTrace (); 
        } the catch (a ClassNotFoundException E) { 
            e.printStackTrace ( ); 
        } the catch (SQLException E) { 
            e.printStackTrace (); 
        } 
    } 
    / *Database connection * / 
    public Connection the getConnection () throws SQLException {
         IF (connPool.size ()> 0 ) {
             // Get a connection from the collection 
            Final Connection Conn = connPool.removeFirst (); 
             // return proxies Connection of 
            return (Connection) the Proxy.newProxyInstance (ConnPool. class .getClassLoader (), conn.getClass (). The getInterfaces (), new new of InvocationHandler () {
                 public Object Invoke (Object Proxy, Method, Method, Object [] args)
                         throws the Throwable {
                     IF ( ! "close".equals (method.getName ())) {
                         return Method.invoke (Conn, args); 
                    } the else { 
                        connPool.add (Conn); 
                        System.out.println ( "closes the current connection, the connection pool and returns the connection .. ....... " ); 
                        System.out.println ( " pool number of connections is "+ connPool.size ());
                         return  null ; 
                    } 
                } 
            }); 
        } the else {
             the throw  new new a RuntimeException (" busy database, try again later ............ " ); 
        } 
    }

    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 the java.sql.Connection;
 Import the java.sql.ResultSet;
 Import java.sql.SQLException;
 Import the java.sql.Statement; 

public  class JdbcUtil { 

    // database connection pool 
    Private  static ConnPool ConnPool = new new ConnPool (); 

    / ** 
     obtaining a connection from the pool * 
     * @return 
     * @throws SQLException
      * / 
    public  static connection the getConnection () throws SQLException {
         return connPool.getConnection (); 
    } 

    / **  
     * close the connection
     *@param Conn 
     * @param ST 
     * @param RS 
     * @throws SQLException 
      * / 
    public  static  void CloseConnection (Connection Conn, the Statement ST, ResultSet RS) throws SQLException { 

        // Close ResultSet object store query results 
        IF (RS! = null ) { 
                rs.Close (); 
        } 

        // close Statement object 
        IF (ST =! null ) { 
                st.close (); 
        } 

        // close the connection 
        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

Call as follows:

JdbcUtil jdbcUtil = new JdbcUtil();

　　String sql = " write SQL statements " ; 
　　Connection Connection = null ; 
　　of Statement of Statement = null ;  　　ResultSet resultSet = null ;

{the try 
　　Connection = jdbcUtil.getConnection (); 
　　Statement = Connection.createStatement (); 
　　the resultSet = Statement.executeQuery (SQL);
　　　　the while (ResultSet.next ()) { 
    　　　　String ID = resultSet.getString ( "ID" ); IF ( ! ID = null ) { // business logic can be written here　　　　　　} 　　　　} 　　} the catch (Exception E) { 
            logger.error ( "data acquisition failure" , E); 
            MSG = createResultJson (. 1, "data acquisition failure!" ); 
   } the finally {
      the try
    　　　　
　　　　　　


 {
       　　jdbcUtil.CloseConnection (Connection, Statement, the resultSet); // remember the last close the stream, or will create too many connections abnormalities reported 
     } the catch (SQLException E) {
      // the TODO Auto-Generated Block the catch 
     e.printStackTrace (); 
     } 
   }