javaWeb 数据库连接池连接数据库

需要的公共jar包 mysql-connector-java-5.0.8-bin.jar(mysql数据库) 　　  ojdbc14.jar(oracle数据库)

A.DBCP 需要jar包: commons-dbcp.jar,commons-pool.jar 以及 .properties 配置文件(直接放src目录下)

#连接设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mysql
username=root
password=root

#<!-- 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=utf8

#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_COMMITTED

package de.bvb.utils;

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;

public class JdbcUtils_DBCP {

    private static DataSource ds = null;
    static {
        try {
            InputStream in = JdbcUtils_DBCP.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
            Properties prop = new Properties();
            prop.load(in);

            ds = BasicDataSourceFactory.createDataSource(prop);
        } catch (Exception e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    public static void release(Connection conn, Statement st, ResultSet rs) {

        if (rs != null) {
            try {
                rs.close(); //throw new 
            } catch (Exception e) {
                e.printStackTrace();
            }
            rs = null;
        }
        if (st != null) {
            try {
                st.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            st = null;
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }
}

B.C3P0  需要jar包: c3p0-0.9.2-pre1.jar,mchange-commons-0.2.jar 以及 c3p0-config.xml 配置文件(直接放src目录下,并且文件名包括后缀名不能修改成别的)

<c3p0-config>
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/mysql</property>
        <property name="user">root</property>
        <property name="password">root</property>
        
        <property name="initialPoolSize">10</property>
        <property name="maxIdleTime">30</property>
        <property name="maxPoolSize">20</property>
        <property name="minPoolSize">5</property>
        <property name="maxStatements">200</property>
    </default-config>
    
    <named-config name="mysql">
        <property name="acquireIncrement">50</property>
        <property name="initialPoolSize">100</property>
        <property name="minPoolSize">50</property>
        <property name="maxPoolSize">1000</property><!-- intergalactoApp adopts a different approach to configuring statement caching -->
        <property name="maxStatements">0</property>
        <property name="maxStatementsPerConnection">5</property>
    </named-config>
    
    <named-config name="oracle">
        <property name="acquireIncrement">50</property>
        <property name="initialPoolSize">100</property>
        <property name="minPoolSize">50</property>
        <property name="maxPoolSize">1000</property><!-- intergalactoApp adopts a different approach to configuring statement caching -->
        <property name="maxStatements">0</property>
        <property name="maxStatementsPerConnection">5</property>
    </named-config>
</c3p0-config>

package de.bvb.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class JdbcUtils_C3P0 {

    private static ComboPooledDataSource ds = null;
    static {
        try {
            ds = new ComboPooledDataSource(); //加载xml文件中默认的配置,也就是<default-config>下面的配置
            //  ds = new ComboPooledDataSource("mysql"); //加载xml文件中的 <named-config name="mysql">下面的配置
        } catch (Exception e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    public static void release(Connection conn, Statement st, ResultSet rs) {

        if (rs != null) {
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            rs = null;
        }
        if (st != null) {
            try {
                st.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            st = null;
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }
}