数据库连接池

数据库连接池3种:DBCP,C3P0,调用TOMCAT中的配置

1.DBCP连接，加载属性文件

 

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

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
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{
			Properties prop = new Properties();
			InputStream in = JdbcUtils_DBCP.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
			prop.load(in);
			BasicDataSourceFactory factory = new BasicDataSourceFactory();
			ds = factory.createDataSource(prop);
		}catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	public static Connection getConnection() throws SQLException{
		return ds.getConnection();  //mysqlConnection
	}
	
	public static void release(Connection conn,Statement st,ResultSet rs){
		
		if(rs!=null){
			try{
			rs.close();
			}catch (Exception e) {}
		}
		
		if(st!=null){
			try{
			st.close();
			}catch (Exception e) {}
		}
		
		if(conn!=null){
			try{
			conn.close();
			}catch (Exception e) {}
		}
		
	}
}

2.C3P0数据库连接池

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class JdbcUtils_C3PO {
	private static ComboPooledDataSource ds;
	static{
		try{
			ds = new ComboPooledDataSource();
			
			/*ds.setDriverClass("com.mysql.jdbc.Driver");
			ds.setJdbcUrl("jdbc:mysql://localhost:3306/day16");
			ds.setUser("root");
			ds.setPassword("root");
			ds.setInitialPoolSize(20);*/
		}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) {}
		}
		
		if(st!=null){
			try{
			st.close();
			}catch (Exception e) {}
		}
		
		if(conn!=null){
			try{
			conn.close();
			}catch (Exception e) {}
		}
		
	}
	
}

配置文件:

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
	
	<default-config>
		
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/wangs</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>
		
	</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>

3. Tomcat的数据池

import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

public class JdbcUtils {
	private static DataSource ds = null;
	static {
		try {
			Context initCtx = new InitialContext();
			Context envCtx = (Context) initCtx.lookup("java:comp/env");
			ds = (DataSource) envCtx.lookup("jdbc/EmployeeDB");
		} catch (Exception e) {
			throw new RuntimeException(e);
		}

	}

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

}

可以在服务器端配置，或是在META-INF中加入context.xml文件

<Context>
	<Resource name="jdbc/EmployeeDB"
            auth="Container"
            type="javax.sql.DataSource"
            username="root"
            password="root"
            driverClassName="com.mysql.jdbc.Driver"
            url="jdbc:mysql://localhost:3306/wangs"
            initialSize="10"
            maxActive="8"
            maxIdle="4"/>
</Context>