数据库连接池

本文来自http://blog.youkuaiyun.com/u012972188 ，引用必须注明出处！

数据库连接池

温馨提醒：为了大家能更好学习，强烈推荐大家看看本人的这篇博客

传统的数据库连接

import java.sql.DriverManager;
import java.sql.SQLException;

import com.mysql.jdbc.Connection;

public class DBUtil {
	private DBUtil() {

	}

	private static DBUtil instance = null;

	public synchronized static DBUtil getInstance() {
		if (instance == null) {
			instance = new DBUtil();
		}
		return instance;
	}

	String className = "com.mysql.jdbc.Driver";
	// "com.microsoft.sqlserver.jdbc.SQLServerDriver";
	String url = "jdbc:mysql://127.0.0.1:3306/chat?useUnicode=true&characterEncoding=gbk";
	// "jdbc:sqlserver://localhost:1433;DatabaseName=TestDB";
	String username = "root";
	String password = "123456";

	public java.sql.Connection getConnection() {
		java.sql.Connection con = null;
		try {
			Class.forName(className);
			con = (Connection) DriverManager.getConnection(url, username,
					password);
		} catch (ClassNotFoundException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
		return con;
	}

	public static void main(String[] args) {
		long began = System.currentTimeMillis();
		for (int i = 0; i < 1000; i++) {

			java.sql.Connection conn = DBUtil.getInstance().getConnection();
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO 自动生成的 catch 块
				e.printStackTrace();
			}
		}
		long end = System.currentTimeMillis();
		System.out.println("直接连接数据库耗时\t" + (end - began) + "\t毫秒");
	}
}

C3P0 数据库连接池的使用

import java.beans.PropertyVetoException;
import java.sql.SQLException;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DBUtilOfC3P0 {
	private DBUtilOfC3P0() {
		cpd = new ComboPooledDataSource();
//		设置 jdbc 信息
		cpd.setUser(username); 
		cpd.setPassword(password);
		cpd.setJdbcUrl(url);
		try {
			cpd.setDriverClass(className);
		} catch (PropertyVetoException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
		//连接池的配置
        cpd.setInitialPoolSize(30);
        cpd.setMaxPoolSize(100);
        cpd.setMinPoolSize(10);
 

	}
	private static ComboPooledDataSource cpd = null;



	private static DBUtilOfC3P0 instance = null;

	public synchronized static DBUtilOfC3P0 getInstance() {
		if (instance == null) {
			instance = new DBUtilOfC3P0();
		}
		return instance;
	}

	String className = "com.mysql.jdbc.Driver";
	// "com.microsoft.sqlserver.jdbc.SQLServerDriver";
	String url = "jdbc:mysql://127.0.0.1:3306/chat?useUnicode=true&characterEncoding=gbk";
	// "jdbc:sqlserver://localhost:1433;DatabaseName=TestDB";
	String username = "root";
	String password = "123456";

	public java.sql.Connection getConnection() {
		java.sql.Connection con=null;
		try {
			con = cpd.getConnection();
		} catch (SQLException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
		return con;
	}

	public static void main(String[] args) {
		long began = System.currentTimeMillis();
		for (int i = 0; i < 1000000; i++) {

			java.sql.Connection conn = DBUtilOfC3P0.getInstance().getConnection();
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO 自动生成的 catch 块
				e.printStackTrace();
			}
		}
		long end = System.currentTimeMillis();
		System.out.println("C3P0耗时\t" + (end - began) + "\t毫秒");
	}
}

DBCP 数据库连接池

import java.sql.SQLException;

import org.apache.tomcat.dbcp.dbcp.BasicDataSource;
import org.apache.tomcat.dbcp.dbcp.DataSourceConnectionFactory;

import com.mysql.jdbc.Connection;

public class DBUtilOfDBCP {
	private DBUtilOfDBCP() {
		bds = new BasicDataSource();
		//JDBC 相关信息 
		bds.setUrl(url);
		bds.setDriverClassName(className);
		bds.setPassword(password);
		bds.setUsername(username);
		 //连接池配置
        // 初始连接数
        bds.setInitialSize(30);
        // 最大的获取连接数
        bds.setMaxActive(100);
        // 最小可用空闲连接数
        bds.setMinIdle(10);
        // 最大可用空闲连接数
        bds.setMaxIdle(30);
        
        dscf = new DataSourceConnectionFactory(bds);

	}

	private static BasicDataSource bds = null;
	private static DataSourceConnectionFactory dscf = null;

	private static DBUtilOfDBCP instance = null;

	public synchronized static DBUtilOfDBCP getInstance() {
		if (instance == null) {
			instance = new DBUtilOfDBCP();
		}
		return instance;
	}

	String className = "com.mysql.jdbc.Driver";
	// "com.microsoft.sqlserver.jdbc.SQLServerDriver";
	String url = "jdbc:mysql://127.0.0.1:3306/chat?useUnicode=true&characterEncoding=gbk";
	// "jdbc:sqlserver://localhost:1433;DatabaseName=TestDB";
	String username = "root";
	String password = "123456";

	public java.sql.Connection getConnection() {
		java.sql.Connection con=null;
		try {
			con= dscf.createConnection();
		} catch (SQLException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
		return con;
	}

	public static void main(String[] args) {
		long began = System.currentTimeMillis();
		for (int i = 0; i < 1000000; i++) {

			java.sql.Connection conn = DBUtilOfDBCP.getInstance().getConnection();
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO 自动生成的 catch 块
				e.printStackTrace();
			}
		}
		long end = System.currentTimeMillis();
		System.out.println("DBCP连接数据库克耗时\t" + (end - began) + "\t毫秒");
	}
}

评价一下这三种数据库的连接方式，第一种常用，没有使用数据库连接池，连接数量较多时，速度慢。第二种是用了数据库连接池，速度居中，第三种耗时最短，但有出错概率较高，建议使用第二种连接方式 ，另附下载地址 http://download.youkuaiyun.com/detail/u012972188/6631021

写在后面，数据库连接需要数据库驱动， DBCP ，C3P0  需要相应的驱动具体下载地址，你可以从网上搜索到，或者直接从上面的下载地址获得