JDBC学习（七）dbcp

dbcp是apache社区一个开源的datasource实现。他依赖于两个包common.pool,common.collecgion两个包。其配置文件格式如下：

 

db.properties:

 

#连接设置

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://localhost:3306/jdbc

username=root

password=

 

#<!-- 初始化连接 -->

initialSize=10

 

#最大连接数量

maxActive=50

 

#<!-- 最大空闲连接 -->

maxIdle=20

 

#<!-- 最小空闲连接 -->

minIdle=5

 

#<!-- 超时等待时间以毫秒为单位 6000毫秒/1000等于60秒 -->

maxWait=60000

 

 

#JDBC驱动建立连接时附带的连接属性属性的格式必须为这样：[属性名=property;]

#注意："user" 与 "password" 两个属性会被明确地传递，因此这里不需要包含他们。

connectionProperties=useUnicode=true;characterEncoding=gbk

 

#指定由连接池所创建的连接的自动提交（auto-commit）状态。

defaultAutoCommit=true

 

#driver default 指定由连接池所创建的连接的只读（read-only）状态。

#如果没有设置该值，则“setReadOnly”方法将不被调用。（某些驱动并不支持只读模式，如：Informix）

defaultReadOnly=

 

#driver default 指定由连接池所创建的连接的事务级别（TransactionIsolation）。

#可用值为下列之一：（详情可见javadoc。）NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE

defaultTransactionIsolation=READ_UNCOMMITTED

 

打开数据源使用的方法：

package cn.itcast.jdbc;

 

import java.io.InputStream;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Properties;

 

import javax.sql.DataSource;

 

import org.apache.commons.dbcp.BasicDataSourceFactory;

 

import cn.itcast.jdbc.datasource.MyDataSource2;

 

/**

 *

 * 2008-12-6

 *

 * @author <a href="mailto:liyongibm@hotmail.com">李勇</a>

 *

 */

public final class JdbcUtils {

       private static String url = "jdbc:mysql://localhost:3306/jdbc";

       private static String user = "root";

       private static String password = "";

       private static DataSource myDataSource = null;

 

       private JdbcUtils() {

       }

 

       static {

              try {

                     Class.forName("com.mysql.jdbc.Driver");

                     // myDataSource = new MyDataSource2();

                     Properties prop = new Properties();

                     // prop.setProperty("driverClassName", "com.mysql.jdbc.Driver");

                     // prop.setProperty("user", "user");

 

                     InputStream is = JdbcUtils.class.getClassLoader()

                                   .getResourceAsStream("dbcpconfig.properties");

                     prop.load(is);

                     myDataSource = BasicDataSourceFactory.createDataSource(prop);

              } catch (Exception e) {

                     throw new ExceptionInInitializerError(e);

              }

       }

 

       public static DataSource getDataSource() {

              return myDataSource;

       }

 

       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();

                                   }

                     }

              }

       }

}