java实现数据库连接的工具类

第一种 (带事务)

package com.china.util;

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


public class BaseDao {

protected Connection conn = null;

/**
* 创建数据库连接
* @throws ClassNotFoundException
* @throws SQLException
*/
protected void openconnection() throws ClassNotFoundException,SQLException{        
try {
if( conn == null || conn.isClosed() ){
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","xx","xx");
//mysql
//Class.forName("com.mysql.jdbc.Driver");
// conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/xe", "root", "root");
            }            
        } catch (ClassNotFoundException e) {            

throw e;
        } catch (SQLException e) {    

throw e;
        }
    }    

/**
* 手动提交事务
* @throws Exception
*/
public void beginTransaction() throws Exception{

this.openconnection();        
conn.setAutoCommit(false);        
    }

/**
* 事务回滚
* @throws Exception
*/
public void rollback() throws Exception{

if(conn != null){            
conn.rollback();            
        }        
    }

/**
* 事务提交
* @throws Exception
*/
public void commit() throws Exception{
if(conn != null){            
conn.commit();                
        }    
    }

/**
* 关闭数据库
* @throws Exception
*/
public void closeResource() throws Exception{        
if(conn != null){
conn.close();
        }                 
    }   
}

第二种(mysql和oracle无事务)推荐！

package com.smn.toolsbean;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DB {
private final String url = "jdbc:mysql://127.0.0.1:3306/blog";
private final String userName = "root";
private final String password = "toor";
private Connection con = null;
private Statement stm=null;

/* 通过构造方法加载数据库驱动 */
public DB(){
try {
Class.forName("com.mysql.jdbc.Driver"); 
        } catch (Exception e) {
e.printStackTrace();
System.out.println("加载数据库驱动失败！");
        }        
    }
/* 创建数据库连接 */
public void createCon() {
try {
con = DriverManager.getConnection(url, userName, password);
        } catch (Exception e) {
e.printStackTrace();
System.out.println("获取数据库连接失败！");
        }
    }
/* 获取Statement对象 */
public void getStm(){
createCon();
try {
stm=con.createStatement();
        } catch (SQLException e) {
e.printStackTrace();
System.out.println("创建Statement对象失败！");
        }
    }
/** 
* @功能 对数据库的增加、修改和删除的操作
* @参数 sql为要执行的SQL语句
* @返回值 boolean型值 
*/
public boolean executeUpdate(String sql) {
System.out.println(sql);
boolean mark=false;
try {
getStm();
int iCount = stm.executeUpdate(sql);
if(iCount>0)                
mark=true;            
else
mark=false;
        } catch (Exception e) {
e.printStackTrace();
mark=false;
        }
return mark;
    }
/* 查询数据库 */
public ResultSet executeQuery(String sql) {
ResultSet rs=null;
try {
getStm();
try {
rs = stm.executeQuery(sql);
            } catch (Exception e) {
e.printStackTrace();
System.out.println("查询数据库失败！");
            }
        } catch (Exception e) {
e.printStackTrace();          
        }
return rs;
    }
/* 关闭数据库的操作 */
public void closed() {
if(stm!=null)
try {
stm.close();
            } catch (SQLException e) {
e.printStackTrace();
System.out.println("关闭stm对象失败！");
            }
if(con!=null)
try {
con.close();
            } catch (SQLException e) {
e.printStackTrace();
System.out.println("关闭con对象失败！");
            }
    }
}