java使用jdbc连接数据库简单实例

package com.tr.jdbc;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import org.apache.commons.dbcp2.BasicDataSource;public class CollectionFactory { private final static String dbDriver = "com.mysql.jdbc.Driver"; private final static String dbUrl="jdbc:mysql://localhost:3306/xtest?useUnicode=true&characterEncoding=UTF-8" ; private final static String dbUser="root"; private final static String dbpwd="root"; private static BasicDataSource dataSource; //创建dbcp的简单数据源并初始化相关属性 static{  dataSource = new BasicDataSource();  dataSource.setDriverClassName(dbDriver);  dataSource.setUrl(dbUrl);  dataSource.setUsername(dbUser);  dataSource.setPassword(dbpwd);  //指定数据库连接池初始化连接数  dataSource.setInitialSize(10);  //设定同时向数据库申请的最大连接数  dataSource.setMaxTotal(50);  //设置连接池中保持的最少连接数量  dataSource.setMinIdle(5);  //其他属相...参考Apache的公开文档 } //创建数据库连接对象--并且多线程并发处理(注意Connection导的是Java.sql的包) public static synchronized Connection creatConnection(){  Connection conn = null;  if(dataSource!=null&&!dataSource.isClosed()){   try {    conn = dataSource.getConnection();   } catch (SQLException e) {    e.printStackTrace();   }  }  return conn; } public static void main(String[] args) {  String sql = "select * from s_t_user";  Connection conn = creatConnection();  Statement statement = null;  ResultSet resultSet = null;  try {   statement = conn.createStatement();   resultSet= statement.executeQuery(sql);   int row = 0;   while(resultSet.next()){    row++;    System.out.println("记录行"+row+"col2:"+resultSet.getString(2));    }  } catch (SQLException e) {   e.printStackTrace();  }finally {   if (conn!=null) {    try {     conn.close();    } catch (SQLException e) {       e.printStackTrace();    }   }  } }}