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Re:求一个比较好用的数据库连接池组件 [Re:CrazyJavar]

yung

发贴: 19
积分: 10

于 2003-04-18 15:42

File: DBConnectionManager.java:

package beans;

/**
* @author
*
*/

import java.util.Vector;
import java.util.Enumeration;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.ResourceBundle;
import java.util.MissingResourceException;

/**
* Database Connection Manager
*/
public class DBConnectionManager {

private static final String OPTION_FILE_NAME = "DBOptions";
private final static DBConnectionManager instance=new DBConnectionManager();
private DBConnectionPool pool;

/**
* Use singleton pattern, only return one instance of DBConnectionManager.
* 取得 DBConnectionManager 实例的唯一方式
* @return DBConnectionManager
*/
public static DBConnectionManager getInstance() {
return instance;
}
/**
* Get a connection
* @return Connection
*/
public Connection getConnection() throws SQLException{
return pool.getConnection();
}
/**
* Free a connection
* @param con connection
* @throws SQLException this method
*/
public void freeConnection(Connection con) throws SQLException{
pool.freeConnection(con);

}

private DBConnectionManager() {
init();
}

private void init() {
String db_driver = "";
String db_url = "";
String db_user = "";
String db_password = "";
int db_maxConn=0;

try {
ResourceBundle res = ResourceBundle.getBundle(OPTION_FILE_NAME);
db_driver = res.getString("DB_DRIVER").trim();
db_url = res.getString("DB_URL").trim();
db_user = res.getString("DB_USER").trim();
db_password = res.getString("DB_PASSWORD").trim();
db_maxConn = Integer.parseInt(res.getString("DB_MAX_CONNECTIONS"));

Class.forName(db_driver);
pool = new DBConnectionPool(db_url,db_user,db_password,db_maxConn);
} catch (Exception ex) {
System.out.println(ex);
}
System.out.println("ConnectionPool Init OK ! " +
"URL : "+ db_url +
", User : " + db_user +
", MaxConn : " + db_maxConn);
}

/**
* Closes all open connections.
*/
public void release() {
pool.release();
}

public String toString() {
return pool.toString();
}
/************************************************************************************
************************************************************************************/
// inner class

class DBConnectionPool {

private Vector freeConnections = new Vector();
private int maxConn;
private int connNumb;

private String URL;
private String user;
private String password;

public DBConnectionPool(String URL, String user, String password,int maxConn) {
this.URL = URL;
this.user = user;
this.password = password;
this.maxConn = maxConn;
}

public synchronized void freeConnection(Connection con) {
freeConnections.addElement(con);
connNumb--;
notifyAll(); // useful??
}

public synchronized Connection getConnection() throws SQLException{
Connection con = null;
if (freeConnections.size() > 0) {
con = (Connection) freeConnections.firstElement();
freeConnections.removeElementAt(0);
try {
if (con.isClosed()) {
con = getConnection();
}
}
catch (SQLException e) {
con = getConnection();
}
}
else if (maxConn == 0 || connNumb < maxConn) {
con = newConnection();
}
if (con != null) {
connNumb++;
}
return con;
}

private Connection newConnection() throws SQLException{
Connection con =DriverManager.getConnection(URL,user, password);
return con;
}

synchronized void release() {
Enumeration allConnections = freeConnections.elements();
while (allConnections.hasMoreElements()) {
Connection con = (Connection) allConnections.nextElement();
try {
con.close();
} catch (SQLException e) {
System.out.println("Can't close connection in DBConnectionPool.");
}
}
freeConnections.removeAllElements();
}

public synchronized String toString() {
String info =
"ConnectionPool(" + URL + "," + user + ")" +
", totalConn =" + connNumb +
", freeConnetion=" + freeConnections.size() +
", max=" + maxConn;
return(info);
}
} /// Inner class End.

}///~
-------------------------------------------------------------------------------------------
DBOptions.properties:

DB_DRIVER = org.mysql......Driver
DB_URL = jdbc:mysql...........
DB_USER = yung
DB_PASSWORD = passwd
DB_MAX_CONNECTIONS = 20
-------------------------------------------------------------------------------------------
File Test.java: (测试一下）
package beans;

/**
* @author
*
* To change this generated comment edit the template variable "typecomment":
* Window>Preferences>Java>Templates.
* To enable and disable the creation of type comments go to
* Window>Preferences>Java>Code Generation.
*/

import java.sql.*;

public class Test {
  public static void main(String[] args) throws Exception {
    DBConnectionManager dbcm = DBConnectionManager.getInstance();

    dbcm.release();
    Connection conn = dbcm.getConnection();

    System.out.println(dbcm);

    Statement stmt = null;
    ResultSet rs = null;
    ResultSetMetaData md = null;

    try {
      stmt = conn.createStatement();
      rs = stmt.executeQuery("select * from users");
      md = rs.getMetaData();
      while (rs.next()) {
        for (int i = 1; i <= md.getColumnCount(); i++) {
          System.out.print(rs.getString Light Bulb

+ " | ");
        }
        System.out.println("");
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      dbcm.freeConnection(conn);
      dbcm.freeConnection(conn1);
    }
    dbcm.release();
    System.out.println(dbcm);

  }
}

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话题树型展开

人气	标题	作者	字数	发贴时间
10292	求一个比较好用的数据库连接池组件	jfml	2	2003-04-18 11:04
9294	Re:求一个比较好用的数据库连接池组件	jfml	12	2003-04-18 12:05
9197	Re:求一个比较好用的数据库连接池组件	jfml	8	2003-04-19 00:46
8648	Re:求一个比较好用的数据库连接池组件	rainman	80	2003-04-19 02:55
8469	Re:求一个比较好用的数据库连接池组件	jeez	52	2003-04-19 20:46
8538	Re:求一个比较好用的数据库连接池组件	harvshen	18	2003-04-22 14:34
8482	Re:求一个比较好用的数据库连接池组件	DesertApple	34	2003-04-18 13:25
9192	Re:求一个比较好用的数据库连接池组件	jfml	16	2003-04-18 13:26
8882	Re:求一个比较好用的数据库连接池组件	yung	6621	2003-04-18 15:42
9262	Re:求一个比较好用的数据库连接池组件	jfml	30	2003-04-18 18:12
8489	Re:求一个比较好用的数据库连接池组件	jeez	72	2003-04-18 19:29
8435	Re:求一个比较好用的数据库连接池组件	black1234	33	2003-04-18 19:31
9505	Re:求一个比较好用的数据库连接池组件	emarket	107	2003-04-22 15:05
9231	Re:求一个比较好用的数据库连接池组件	jfml	63	2003-04-18 20:10
8501	Re:求一个比较好用的数据库连接池组件	jeez	20	2003-04-18 23:23

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