一、常用连接池：
（1）C3P0（2）Druid(德鲁伊)（3）DBCP（4）JNDI
二、Druid(德鲁伊)：
1、配置说明：
（1）导入jar包：druid.jar；
（2）配置properties格式的配置文件：文件位置随意；命名一般db_server.properties；
2、properties配置：
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf-8
username=root
password=123456
filters=stat
initialSize=2
maxActive=300
maxWait=60000
timeBetweenEvictionRunsMillis=60000
minEvictableIdleTimeMillis=300000
validationQuery=SELECT 1
testWhileIdle=true
testOnBorrow=false
testOnReturn=false
poolPreparedStatements=false
maxPoolPreparedStatementPerConnectionSize=200
3、工具类封装：
import java.io.File; import java.io.FileInputStream; import java.io.InputStream; import java.sql.SQLException; import java.util.Properties; import com.alibaba.druid.pool.DruidDataSource; import com.alibaba.druid.pool.DruidDataSourceFactory; import com.alibaba.druid.pool.DruidPooledConnection; /** * 要实现单例模式，保证全局只有一个数据库连接池 */ public class DBPoolConnection { private static DBPoolConnection dbPoolConnection = null; private static DruidDataSource druidDataSource = null; static { Properties properties = loadPropertiesFile("src/druid.properties"); try { druidDataSource = (DruidDataSource) DruidDataSourceFactory.createDataSource(properties); // DruidDataSrouce工厂模式 } catch (Exception e) { e.printStackTrace(); System.out.println("配置失败"); } } /** * 数据库连接池单例 * * @return */ public static synchronized DBPoolConnection getInstance() { if (null == dbPoolConnection) { dbPoolConnection = new DBPoolConnection(); } return dbPoolConnection; } /** * 返回druid数据库连接 * * @return * @throws SQLException */ public DruidPooledConnection getConnection() throws SQLException { return druidDataSource.getConnection(); } /** * @param string 配置文件名 * @return Properties对象 */ private static Properties loadPropertiesFile(String fullFile) { String webRootPath = null; if (null == fullFile || fullFile.equals("")) { throw new IllegalArgumentException("Properties file path can not be null" + fullFile); } webRootPath = DBPoolConnection.class.getClassLoader().getResource("").getPath(); webRootPath = new File(webRootPath).getParent(); InputStream inputStream = null; Properties p = null; try { inputStream = new FileInputStream(new File(webRootPath + File.separator + fullFile)); p = new Properties(); p.load(inputStream); } catch (Exception e) { e.printStackTrace(); } finally { try { if (null != inputStream) { inputStream.close(); } } catch (Exception e) { e.printStackTrace(); } } return p; } /** * @param Object 需要关闭的资源 * @return */ public static void closeAll(Object... objects) { for (int i = 0; i < objects.length; i++) { if(objects[i] instanceof Statement) { Statement statement = (Statement)objects[i]; if(statement!=null) { try { statement.close(); } catch (SQLException e) { e.printStackTrace(); } } } if(objects[i] instanceof ResultSet) { ResultSet resultSet = (ResultSet)objects[i]; if(resultSet!=null) { try { resultSet.close(); } catch (SQLException e) { e.printStackTrace(); } } } if(objects[i] instanceof Connection) { Connection connection = (Connection)objects[i]; if(connection!=null) { try { connection.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } }
4、配置sql监控：在web.xml中配置；
<servlet> <servlet-name>DruidStatView</servlet-name> <servlet-class>com.alibaba.druid.support.http.StatViewServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>DruidStatView</servlet-name> <url-pattern>/druid/*</url-pattern> </servlet-mapping>
三、DBCP：
1、配置说明：
（1）导入jar包；
（2）配置properties文件；
2、创建简单工具类：
3、配置文件：
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/servlettest
username=root
password=000000
maxTotal=30
maxIdle=10
minIdle=5
maxWaitMillis=1000
removeAbandonedOnMaintenance=true
removeAbandonedOnBorrow=true
removeAbandonedTimeout=1
四、C3P0：
1、配置说明：
（1）导入jar包；
（2）配置c3p0-config.xml：必须再src目录下；名字不能变；
2、xml配置：
<?xml version="1.0" encoding="UTF-8"?> <c3p0-config> <!--默认配置--> <default-config> <property name="initialPoolSize">10</property> <property name="maxIdleTime">30</property> <property name="maxPoolSize">100</property> <property name="minPoolSize">10</property> <property name="maxStatements">200</property> </default-config> <!--配置连接池mysql--> <named-config name="mysql"> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql://localhost:3306/CoupleSpace</property> <property name="user">root</property> <property name="password">root</property> <property name="initialPoolSize">10</property> <property name="maxIdleTime">30</property> <property name="maxPoolSize">100</property> <property name="minPoolSize">10</property> <property name="maxStatements">200</property> </named-config> <!--配置连接池2--> ...... <!--配置连接池3--> ...... <!--配置连接池4--> ...... </c3p0-config>
3、使用说明：
（1）获取c3q0对象：new ComboPooledDataSource(["mySource"])；
//参数mySource：为<named-config name="标识"> </name-config>标签中的name属性；
//参数可以不写为默认；
（2）获取Connection：new ComboPooledDataSource().getConnection()；
（3）归还Connection：.close()；
原文：https://www.cnblogs.com/Tractors/p/11300584.html