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数据库连接池类，用于获取数据库连接。利用单例模式保证所有的连接都只通过一个连接池管理。  package com.mousewheel.dbcon;import java.io.InputStream;import java.sql.Connection;import java.sql.SQLException;import java.util.Properties;import com.mchange.v2.c3p0.ComboPooledDataSource;public class DBPool { private static DBPool instance; private ComboPooledDataSource dataSource; static{ instance = new DBPool(); } private DBPool() { try { dataSource = new ComboPooledDataSource(); Properties prop = new Properties(); InputStream in = DBPool.class.getClassLoader().getResourceAsStream('db.properties'); prop.load(in); dataSource.setDriverClass(prop.getProperty('jdbcdriver')); dataSource.setJdbcUrl(prop.getProperty('url')); dataSource.setUser(prop.getProperty('username')); dataSource.setPassword(prop.getProperty('password')); } catch (Exception e) { e.printStackTrace(); } } public static DBPool getInstance(){ return instance; } public Connection getConnection() throws SQLException { return dataSource.getConnection(); }} DBUtil类，包装DBPool，简化使用 package com.mousewheel.dbcon;import java.sql.Connection;import java.sql.SQLException;public class DbUtil { public static Connection getConnection() throws SQLException { DBPool pool = DBPool.getInstance(); return pool.getConnection(); }}
测试代码，和不使用连接池的情况做对比 package com.mousewheel.dbcon;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.Properties;import java.io.InputStream;import com.mousewheel.dbcon.DbUtil; class App { public static void main(String[] args) { // use c3p0 connection pool try { for (int i = 0; i < 100;="">) { long beginTime = System.currentTimeMillis(); Connection con = DbUtil.getConnection(); // 执行查询语句 String sql = 'select * from student'; PreparedStatement ps = con.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while (rs.next()) { // System.out.println(rs.getString(1)); } con.close(); long endTime = System.currentTimeMillis(); System.out.println(String.format('第%s次,%s', i, (endTime - beginTime))); } } catch (Exception e) { e.printStackTrace(); } // jdbc without using conection pool try { for (int i = 0; i < 100;="">) { long beginTime = System.currentTimeMillis(); Properties prop = new Properties(); InputStream in = App.class.getClassLoader().getResourceAsStream('db.properties'); prop.load(in); Class.forName(prop.getProperty('jdbcdriver')); Connection con = DriverManager.getConnection(prop.getProperty('url'), prop.getProperty('username'), prop.getProperty('password')); String sql = 'select * from student'; PreparedStatement ps = con.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while (rs.next()) { // System.out.println(rs.getString(1)); } con.close(); long endTime = System.currentTimeMillis(); System.out.println(String.format('第%s次,%s', i, (endTime - beginTime))); } } catch (Exception e) { e.printStackTrace(); } }}
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