使用数据库连接池提高执行效率

利用数据库连接池可有效提高数据库操作效率，避免重复打开和关闭数据库连接。具体方法和测试结果如下：

首先建立一个属性文件，将相应的数据库连接方法加入其中：

属性文件具体设定如下：

driverClassName=oracle.jdbc.driver.OracleDriver

username=ORATEST

password=ORATEST

url=jdbc\:oracle\:thin\:@vOracle.imStudio.com\:1521\:vOracle

poolSize=10

然后建立数据库连接池操作类ConnectionPoolTool.java

import java.io.FileInputStream;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.Properties;

import java.util.Vector;



public class ConnectionPoolTool {

    

    private Vector<Connection> pool;

    private String url;

    private String username;

    private String password;

    private String driverClassName;



    /**

     * 连接池的大小，也就是连接池中有多少个数据库连接。

     */

    private int poolSize = 1;



    private static ConnectionPoolTool instance = null;



    /**

     * 私有的构造方法，禁止外部创建本类的对象，要想获得本类的对象，通过<code>getIstance</code>方法。

     * 使用了设计模式中的单子模式。

     */

    private ConnectionPoolTool() {

        init();

    }



    /**

     * 连接池初始化方法，读取属性文件的内容 建立连接池中的初始连接

     */

    private void init() {

        pool = new Vector<Connection>(poolSize);

        readConfig();

        addConnection();

    }



    /**

     * 返回连接到连接池中

     */

    public synchronized void release(Connection conn) {

        pool.add(conn);



    }



    /**

     * 关闭连接池中的所有数据库连接

     */

    public synchronized void closePool() {

        for (int i = 0; i < pool.size(); i++) {

            try {

                ((Connection) pool.get(i)).close();

            } catch (SQLException e) {

                e.printStackTrace();

            }

            pool.remove(i);

        }

    }



    /**

     * 返回当前连接池的一个对象

     */

    public static ConnectionPoolTool getInstance() {

        if (instance == null) {

            instance = new ConnectionPoolTool();

        }

        return instance;

    }



    /**

     * 返回连接池中的一个数据库连接

     */

    public synchronized Connection getConnection() { 

        if (pool.size() > 0) {

            Connection conn = pool.get(0);

            pool.remove(conn);

            return conn;

        } else {

            return null;

        }

    }



    /**

     * 在连接池中创建初始设置的的数据库连接

     */

    private void addConnection() {

        Connection conn = null;

        for (int i = 0; i < poolSize; i++) {



            try {

                Class.forName(driverClassName);

                conn = java.sql.DriverManager.getConnection(url, username, password);

                pool.add(conn);



            } catch (ClassNotFoundException e) {

                e.printStackTrace();

            } catch (SQLException e) {

                e.printStackTrace();

            }



        }

    }



    /**

     * 读取设置连接池的属性文件

     */

    private void readConfig() {

        try {

            String path = System.getProperty("user.dir") + "\\dbpool.properties";

            FileInputStream is = new FileInputStream(path);

            Properties props = new Properties();

            props.load(is);

            this.driverClassName = props.getProperty("driverClassName");

            this.username = props.getProperty("username");

            this.password = props.getProperty("password");

            this.url = props.getProperty("url");

            this.poolSize = Integer.parseInt(props.getProperty("poolSize"));

        } catch (Exception e) {

            e.printStackTrace();

            System.err.println("读取属性文件出错. ");        

        }

    }



}

再加入数据库连接池测试方法ConnectionPoolTest.java

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;



public class ConnectionPoolTest {



    /**

     * @param args

     */

    public static void main(String[] args)throws Exception {

        // TODO Auto-generated method stub

        String sql = "select userid,username,password from tbluser";

        long start = System.currentTimeMillis();

        ConnectionPoolTool pool = null;



        for (int i = 0; i < 100; i++) {

            pool = ConnectionPoolTool.getInstance();

            Connection conn = pool.getConnection();

            Statement stmt = conn.createStatement();

            ResultSet rs = stmt.executeQuery(sql);

            while (rs.next()) {

            }

            rs.close();

            stmt.close();

            pool.release(conn);

        }

        pool.closePool();

        System.out.println("经过100次的循环调用，使用连接池花费的时间:" + (System.currentTimeMillis() - start) + "ms\n");



        String hostName = "vOracle.imStudio.com";

        String driverClass = "oracle.jdbc.driver.OracleDriver";

        String url = "jdbc:oracle:thin:@" + hostName + ":1521:vOracle";

        String user = "ORATEST";

        String password = "ORATEST";

        start = System.currentTimeMillis();

        

        for (int i = 0; i < 100; i++) {

            Class.forName(driverClass);

            Connection conn = DriverManager.getConnection(url, user, password);

            Statement stmt = conn.createStatement();

            ResultSet rs = stmt.executeQuery(sql);

            while (rs.next()) {

            }

            rs.close();

            stmt.close();

            conn.close();

        }

        System.out.println("经过100次的循环调用，不使用连接池花费的时间:" + (System.currentTimeMillis() - start) + "ms");

    }



}

编写完成后，进行测试运行，如下为我本机测试结果：