自己写的一个JDBC连接池,比较粗糙

1和2是连接池,3和4 是一个驱动,用来测试或者插入数据用的.

程序运行后命令举例:

new 100  申请100个连接

drop 100  把100放回到池子里

query 100000 <SQL>  执行SQL语句100000次,比如插入数据

quit 退出

//1.connPool.java

package Data;

import java.util.ArrayList;

import java.util.List;

import java.sql.*;




public class connPool {



    private List<Connection> pool; //it contains connections



    public connPool()

    {

        pool=new ArrayList<Connection>();

    }



    synchronized public boolean putConn(Connection conn) throws SQLException //put connection back

    {

        if(conn==null||conn.isClosed()) //check,throws SQLException

            return false;

        else

        {

            return pool.add(conn);

        }

    }



    synchronized public Connection getConn() //fetch a connection

    {

        if(pool.size()<=0)

            return null;

        else

        {

            return pool.remove(0);

        }

    }



    synchronized public boolean reduceOne() //reduce the connections storage

    {

        if(pool.size()<=0)

            return false;

        else

        {

            try {

                pool.remove(0).close();

            } catch (SQLException e) {

                e.printStackTrace();

                return false;

            }

            return true;

        }

    }



    public int getNum()  //how many connections is there

    {

        return pool.size();

    }



}

//2.DBDriver.java
package Data;


import java.sql.*;


public class DBDriver {


    static final int NumWhenStart = 10; // how many conns should be created whenstart


    static final int NumWhenIncrease = 5;// how many conns should add when thereis few conns


    static final int NumJudgeOver = 20; // num to judge if the pool has too many conns;


    static final int NumReduceTo = 10; // num should the pool reduce to

    static final int NumLowCase = 2; //num few conns


    private String host; //host name
    private String user; //database user
    private String pwd; //password
    private String database; //database name
    private String driverName; //JDBC Driver
        private String dbURL; //database connection url
    private connPool pool; //connection pool

    private static DBDriver instance = null; //singleton instance


    public static DBDriver getInstance() {  //singleton
        if (instance == null) {
            synchronized (DBDriver.class) {
                if (instance == null) {
                    try {
                        instance = new DBDriver();
                    } catch (Exception e) {
                        e.printStackTrace();
                        return null;
                    }
                }
            }
        }
        return instance;
    }


    private DBDriver() throws Exception { //constructor
        pool = new connPool();
        host = "localhost";
        user = "sa";
        pwd = "put yours pwd here";
        database = "innov";
        driverName = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
        dbURL = "jdbc:sqlserver://" + host + ":1433; DatabaseName="
                + database;
        Class.forName(driverName);
        for (int i = 0; i < NumWhenStart; i++) {
            Connection conn = DriverManager.getConnection(dbURL, user, pwd);
            pool.putConn(conn);
        }
    }


    public Connection getConn() { //get a connection
        Connection conn = null;
        if (pool.getNum() <= NumLowCase) {
            try {
                Class.forName(driverName);
                for (int i = 0; i < NumWhenIncrease; i++) {
                    conn = DriverManager.getConnection(dbURL, user, pwd);
                    pool.putConn(conn);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return pool.getConn();
    }


    public boolean close(Connection conn) {  //put connections back
        boolean bool = false;
        try {
            bool = pool.putConn(conn);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        if (pool.getNum() > NumJudgeOver) {
            while (pool.getNum() > NumReduceTo)
                pool.reduceOne();
        }
        return bool;
    }


    public int getNum() { //return pool's connection number
        return pool.getNum();
    }
}
/***************************上面的是连接池**********************************/
/***************************这下面的是一个驱动程序***********************/
//3.SqlThread.java          //use multiple thread
import java.sql.*;
public class SqlThread extends Thread
{
    Connection conn;
    String sql;
    int times;
    public SqlThread(String name,Connection conn,String sql,int times)
    {
        super(name);
        this.times=times;
        this.sql=sql;
        this.conn=conn;
    }


    @Override
    public void run()
    {
        try
        {
            Statement stmt=conn.createStatement();
            for(int i=0;i<times;i++)
            {
                stmt.execute(sql);
                System.out.print("Thread "+this.getName()+" Reporting:"+(i+1)+" querys done.\n");
                sleep(3);
            }
        }catch(Exception e)
        {
            e.printStackTrace();
        }
        System.out.print("Thread "+this.getName()+" quit."+times+" querys done.\n");
    }
}


//4.test.java


import java.sql.*;
import java.util.*;
import Data.DBDriver;


public class test {


    /**
     * @param args
     */
    public static void main(String[] args) {
        System.out.print("program start\n");
        DBDriver dbd = DBDriver.getInstance();
        List<Connection> connList = new ArrayList<Connection>();
        for(int i=0;i<3;i++)
        {
            connList.add(dbd.getConn());
        }
        System.out.print("using " + connList.size() + " conns,while "
                + dbd.getNum() + " in pool\n");
        Scanner jin = new Scanner(System.in);
        String cmd;
        int flag = 0;
        while (jin.hasNext()) {
            cmd = jin.next();
            if (flag == 0) {
                if (cmd.equals("quit")) {
                    System.out.print("Bye Bye");
                    break;
                } else if (cmd.equals("new")) {
                    flag = 1;
                } else if (cmd.equals("drop")) {
                    flag = 2;
                } else if (cmd.equals("query")) {
                    flag = 3;
                } else {
                    System.out.print("Unknown command\n");
                }
            } else {
                if (flag == 1) {
                    int num = Integer.parseInt(cmd);
                    for (int i = 0; i < num; i++) {
                        connList.add(dbd.getConn());
                    }
                    System.out.print("System:operation done!\nusing "
                            + connList.size() + " conns,while " + dbd.getNum()
                            + " in pool\n");
                    flag = 0;
                } else if (flag == 2) {
                    int num = Integer.parseInt(cmd);
                    int size = connList.size();
                    for (int i = 0; i < ((num > size) ? size : num); i++) {
                        if (dbd.close(connList.get(0))) {
                            connList.remove(0);
                        } else {
                            System.out.print("fail when drop " + i + "\n");
                        }
                    }
                    System.out.print("System:operation done!\nusing "
                            + connList.size() + " conns,while " + dbd.getNum()
                            + " in pool\n");
                    flag = 0;
                } else if (flag == 3) {
                    int num = Integer.parseInt(cmd);
                    String sql = jin.nextLine();
                    for (int i = 0; i < 3; i++) {
                        try {
                            Thread t=new SqlThread(String.valueOf(i),connList.get(i),sql,num/3+((i<2)?0:(num%3)));
                            t.start();
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                    flag = 0;
                } else if (flag == 4) {
                    int num = Integer.parseInt(cmd);
                    int size = connList.size();
                    String sql = jin.nextLine();
                    Statement stmt = null;
                    for (int i = 0; i < ((num > size) ? size : num); i++) {
                        try {
                            Thread t=new SqlThread(String.valueOf(i),connList.get(i),sql,1);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.print("System:operation done!\nusing "
                            + connList.size() + " conns,while " + dbd.getNum()
                            + " in pool\n");
                    flag = 0;
                }
            }
        }
    }
}