关于DBCP及使用。纯JDBC架构。

DBCP(DataBase connection pool),数据库连接池。

是 apache 上的一个 Java 连接池项目，也是 tomcat 使用的连接池组件。单独使用dbcp需要3个包：common-dbcp.jar,common-pool.jar,common-collections.jar由于建立数据库连接是一个非常耗时耗资源的行为，所以通过连接池预先同数据库建立一些连接，放在内存中，应用程序需要建立数据库连接时直接到连接池中申请一个就行，用完后再放回去。

目前hibernate默认的连接方式就是DBCP，可见其重要性。不过话说hibernate只是一个框架，效率低多了，基础的才是笑到最后的。使用DBCP的连接池可以快速取存连接。进行一系列操作。

不说了，土豆我就直接上代码了。纯JDBC效率肯定比hibernate高哦。说不定哪天hibernate没落了。它只是工具，底层才是王道。

package com.sinoglobal.db;    import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.ResultSet;  import java.sql.SQLException;  import java.sql.Statement;  import java.util.Locale;  import java.util.ResourceBundle;    import org.apache.commons.dbcp.ConnectionFactory;  import org.apache.commons.dbcp.DriverManagerConnectionFactory;  import org.apache.commons.dbcp.PoolableConnectionFactory;  import org.apache.commons.dbcp.PoolingDriver;  import org.apache.commons.pool.ObjectPool;  import org.apache.commons.pool.impl.GenericObjectPool;    @SuppressWarnings("unchecked")  public class PoolManager {      private static String driver = "net.sourceforge.jtds.jdbc.Driver"; // 驱动      private static String url = ""; // URL      private static String name = "sa"; // 用户名      private static String password = ""; // 密码      private static Class driverClass = null;      private static ObjectPool connectionPool = null;      private static String poolname = "";      private static ResourceBundle rb;        /**      * 初始化数据源      */      private static synchronized void initDataSource() {          if (driverClass == null) {              try {                  driverClass = Class.forName(driver);              } catch (ClassNotFoundException e) {                  e.printStackTrace();              }          }      }        /**      * 装配配置文件 initProperties      */      private static void loadProperties() {          rb = ResourceBundle.getBundle("config", Locale.getDefault());          driver = rb.getString("jdbc.sql.driverClassName");          url = rb.getString("jdbc.sql.url");          name = rb.getString("jdbc.sql.username");          password = rb.getString("jdbc.sql.password");          poolname = rb.getString("jdbc.sql.poolname");      }        /**      * 连接池启动      *       * @throws Exception      */      public static void StartPool() {          loadProperties();          initDataSource();          if (connectionPool != null) {              ShutdownPool();          }          try {              connectionPool = new GenericObjectPool(null);              ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(                      url, name, password);              new PoolableConnectionFactory(connectionFactory, connectionPool,                      null, null, false, true);              Class.forName("org.apache.commons.dbcp.PoolingDriver");              PoolingDriver driver = (PoolingDriver) DriverManager                      .getDriver("jdbc:apache:commons:dbcp:");              driver.registerPool(poolname, connectionPool);          } catch (Exception e) {              e.printStackTrace();          }      }        /**      * 释放连接池      */      public static void ShutdownPool() {          try {              PoolingDriver driver = (PoolingDriver) DriverManager                      .getDriver("jdbc:apache:commons:dbcp:");              driver.closePool(poolname);          } catch (SQLException e) {              e.printStackTrace();          }      }        /**      * 取得连接池中的连接      *       * @return      */      public static Connection getConnection() {          Connection conn = null;          if (connectionPool == null)              StartPool();          try {              conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:"                      + poolname);          } catch (SQLException e) {              e.printStackTrace();          }          return conn;      }        /**      * 获取连接 getConnection      *       * @param name      * @return      */      public static Connection getConnection(String name) {          return getConnection();      }        /**      * 释放连接 freeConnection      *       * @param conn      */      public static void freeConnection(Connection conn) {          if (conn != null) {              try {                  conn.close();              } catch (SQLException e) {                  e.printStackTrace();              }          }      }        /**      * 释放连接 freeConnection      *       * @param name      * @param con      */      public static void freeConnection(String name, Connection con) {          freeConnection(con);      }        /**      * 例子 main      *       * @param args      */      public static void main(String[] args) {          try {              Connection conn = PoolManager.getConnection();              System.out.println(conn.isClosed());              if (conn != null) {                  Statement statement = conn.createStatement();                  ResultSet rs = statement                          .executeQuery("select * from test2..log");                  int c = rs.getMetaData().getColumnCount();                  while (rs.next()) {                      System.out.println();                      for (int i = 1; i <= c; i++) {                          System.out.print(rs.getObject(i));                      }                  }                  rs.close();              }              PoolManager.freeConnection(conn);          } catch (SQLException e) {              e.printStackTrace();          }        }    }