java數據庫鏈接池

時間  2019-11-08
標籤 java 數據庫 鏈接 欄目 Java 简体版
原文   原文鏈接

        web項目都會使用數據庫，而數據庫訪問會影響系統性能（I/O操做）。創建數據庫鏈接是一個很是耗時耗資源的操做，經過配置鏈接池能夠在系統啓動時就分配並維護必定數量的鏈接，保持最低數量的鏈接數,經過設定鏈接池最大鏈接數來防止系統無盡的與數據庫鏈接。這樣在每次數據請求方須要鏈接時，直接從鏈接池獲取，使用完畢以後再放回去，這樣就能夠儘量減小沒必要要的數據庫鏈接消耗，緩解數據庫的訪問壓力，減輕對系統性能的影響。java

        java經常使用的數據庫鏈接池主要有 DBCP 和 C3P0；mysql

1、DBCP

DBCP(DataBase connection pool),數據庫鏈接池。是 apache 上的一個 Java 鏈接池項目，也是Tomcat 在 7.0 之前的版本使用的鏈接池組件。web

使用DBCP應該導入commons-dbcp-x.x.jar、commons-pool-x.x.jar、commons-logging-x.x.jarsql

commons-dbcp最新版本是Apache Commons DBCP 2.1.1 for JDBC 4.1 (Java 7.0+)數據庫

Apache Commons Pool 2.4.2 (Java 6.0+)apache

Apache Commons Logging 1.2框架

測試實例ide

TestDBCP.javaoop

package cn.iborder.utils;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSource;
import org.apache.commons.dbcp2.BasicDataSourceFactory;
import org.junit.Test;

public class TestDBCP {
	
	//硬編碼方式實現鏈接池
	@Test
	public void test1() {
		Connection con = null;
		PreparedStatement pstat = null;
		ResultSet rs = null;
		
		BasicDataSource dataSource = new BasicDataSource();
		dataSource.setDriverClassName("com.mysql.jdbc.Driver");
		dataSource.setUrl("jdbc:mysql://localhost/test");
		dataSource.setUsername("root");
		dataSource.setPassword("root");
		dataSource.setInitialSize(3);
		//dataSource.setMaxActive(6); //DBCP2.0以上版本已經移除此方法，由 setMaxTotal()代替
		dataSource.setMaxTotal(6);	//最大鏈接數
		dataSource.setMaxIdle(5); 	//最大空閒鏈接數.
		dataSource.setMinIdle(4);
		
		try {
			con = dataSource.getConnection();
			pstat = con.prepareStatement("select * from admin");
			rs = pstat.executeQuery();
			while (rs.next()) {
				System.out.println(rs.getInt(1)+"\t"+rs.getString(2)+"\t"+rs.getString(3));
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				if(rs != null){
					rs.close();
					rs=null;
				}
				if(pstat != null){
					pstat.close();
					pstat=null;
				}
				if (con != null && !con.isClosed()) {
					con.close();
					con=null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
	}
	
	//配置文件方式實現鏈接池
	@Test
	public void test2() {
		Connection con = null;
		PreparedStatement pstat = null;
		ResultSet rs = null;
		try {
			Properties prop = new Properties();
			BufferedInputStream in = (BufferedInputStream) this.getClass().getResourceAsStream("/db.properties");
			//FileInputStream in = (FileInputStream) TestDBCP.class.getResourceAsStream("/db.properties");//拋異常
			prop.load(in);
			DataSource dataSource = BasicDataSourceFactory.createDataSource(prop);
			con = dataSource.getConnection();
			pstat = con.prepareStatement("select * from admin");
			rs = pstat.executeQuery();
			while (rs.next()) {
				System.out.println(rs.getInt(1)+"\t"+rs.getString(2)+"\t"+rs.getString(3));
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				if(rs != null){
					rs.close();
					rs=null;
				}
				if(pstat != null){
					pstat.close();
					pstat=null;
				}
				if (con != null && !con.isClosed()) {
					con.close();
					con=null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
	}

}

db.properties性能

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/test
username=root
password=root
InitialSize=3
MaxTotal=6
MaxIdle=5
MinIdle=4

2、C3P0

C3P0是一個開放源代碼的JDBC鏈接池，最經常使用的鏈接池技術，Spring/Hibernate框架默認支持C3P0

使用C3P0 應該導入c3p0.xxxx.jar和mchange-commons-java-x.x.x.jar

C3P0最新版本是C3P0 0.9.5.2
核心類：CombopooledDataSource
測試實例

TestC3P0.java

package cn.iborder.utils;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class TestC3P0 {

	//硬編碼方式實現鏈接池
	@Test
	public void test1(){
		Connection con = null;
		PreparedStatement pstat = null;
		ResultSet rs = null;
		
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setDriverClass("com.mysql.jdbc.Driver");
			dataSource.setJdbcUrl("jdbc:mysql://localhost/test");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			dataSource.setInitialPoolSize(3);
			dataSource.setMaxPoolSize(6);
			dataSource.setMaxIdleTime(1000);
			
			con = dataSource.getConnection();
			pstat = con.prepareStatement("select * from admin");
			rs = pstat.executeQuery();
			while (rs.next()) {
				System.out.println(rs.getInt(1)+"\t"+rs.getString(2)+"\t"+rs.getString(3));
			}
		} catch (PropertyVetoException e) {
			// TODO: handle exception
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}  finally {
			try {
				if(rs != null){
					rs.close();
					rs=null;
				}
				if(pstat != null){
					pstat.close();
					pstat=null;
				}
				if (con != null && !con.isClosed()) {
					con.close();
					con=null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
	}
	
	//配置文件方式實現鏈接池
	@Test
	public void test2() {
		Connection con = null;
		PreparedStatement pstat = null;
		ResultSet rs = null;
		try {
			//讀取默認數據庫
			//ComboPooledDataSource dataSource = new ComboPooledDataSource();
			
			//讀取指定name的數據庫
			ComboPooledDataSource dataSource = new ComboPooledDataSource("otherDB");
			
			con = dataSource.getConnection();
			pstat = con.prepareStatement("select * from admin");
			rs = pstat.executeQuery();
			while (rs.next()) {
				System.out.println(rs.getInt(1)+"\t"+rs.getString(2)+"\t"+rs.getString(3));
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}  finally {
			try {
				if(rs != null){
					rs.close();
					rs=null;
				}
				if(pstat != null){
					pstat.close();
					pstat=null;
				}
				if (con != null && !con.isClosed()) {
					con.close();
					con=null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
	}
}

c3p0-config.xml

<c3p0-config>
	<!-- 默認數據庫 -->
	<default-config>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="user">root</property>
		<property name="password">root</property>
		<property name="initialPoolSize">3</property>
		<property name="maxPoolSize">6</property>
		<property name="maxIdleTime">1000</property>

		<user-overrides user="swaldman">
			<!-- 
			<property name="unreturnedConnectionTimeout">5</property>
			<property name="debugUnreturnedConnectionStackTraces">true</property> 
			-->
			<!-- <property name="preferredTestQuery">select poop from doop</property> -->
			<!-- intentionally broken -->
		</user-overrides>

	</default-config>

	<!-- 配置其餘是數據庫 -->
	<named-config name="otherDB">
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="user">root</property>
		<property name="password">root</property>
		<property name="initialPoolSize">3</property>
		<property name="maxPoolSize">6</property>
		<property name="maxIdleTime">1000</property>
	</named-config>

</c3p0-config>
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