JDBC性能的优化

package cn.itcast.jdbc.datasource;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;

public class MyDataSource {

    private static String url="jdbc:mysql://localhost:3306/jdbc";
    private static String user="root";
    private static String password="admin";

    private LinkedList<Connection> connectionsPool=new LinkedList<Connection>();

    public MyDataSource(){
        for(int i=0;i<10;i++){
             try {
                 //先入先出的算法
                this.connectionsPool.addLast(this.createConnection());
            } catch (SQLException e) {
                throw new ExceptionInInitializerError(e);
            }
        }
    }

     public Connection getConnection(){
         return this.connectionsPool.removeFirst();
     }
     private Connection createConnection() throws SQLException{
         return DriverManager.getConnection(url, user, password);
     }

     public void free(Connection conn){
         this.connectionsPool.addLast(conn);
     }

}

 

package cn.itcast.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import cn.itcast.jdbc.datasource.MyDataSource;

public final class JdbcUtils {

    private static String url="jdbc:mysql://localhost:3306/jdbc";
    private static String user="root";
    private static String password="admin";
    private static MyDataSource myDataSource=null;
    private JdbcUtils(){
    }

    static{

        try{
            Class.forName("com.mysql.jdbc.Driver");
            myDataSource=new MyDataSource();
        }catch(ClassNotFoundException e){
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection()throws SQLException{
        //return DriverManager.getConnection(url,user,password);
        return myDataSource.getConnection();
    }

    public static void free(ResultSet rs,Statement st,Connection conn){
        try{
            if(rs!=null)
                rs.close();
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try{
                if(st!=null)
                    st.close();
            }catch(SQLException e){
                e.printStackTrace();
            }finally{
                if(conn!=null)
                    try{
                        //conn.close();
                        myDataSource.free(conn);
                    }catch(Exception e){
                        e.printStackTrace();
                    }
            }
        }
    }
}

编写一个基本的连接池来实现连接的复用。

注意：removeLast是LinkedList所独有的方法。

所以只能写private LinkedList connectionsPool=new LinkedList();

不能写成private List connectionsPool=new LinkedList();这种面向接口的编程。切记，切记！