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();

     }

    }

   }

  }

}