Java_JDBC连接数据库

 package com.accp.dao;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;

 /**
  * 持久类父类
  * @author Administrator
  *
  */
 public abstract class BaseDao {
     private static final String DB_DRIVER = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
     private static final String DB_URL = "jdbc:sqlserver://localhost:1433;databasename=epet";
     private static final String DB_USER = "sa";
     private static final String DB_PWD = "sa";

     protected Connection conn = null;
     protected PreparedStatement ps = null;
     protected ResultSet rs = null;

     static{
         //1、加载驱动类
         try {
             Class.forName(DB_DRIVER);
         } catch (ClassNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }

     /**
      * 打开连接方法
      * @return
      */
     protected void openConn(){
         //2、创建连接
         try {
             conn = DriverManager.getConnection(DB_URL,DB_USER,DB_PWD);
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }

     /**
      * 执行增加、修改、删除
      * @param sql
      * @param paras
      * @return
      */
     // select count(*) from [master] where name=? and password=?
     // Object[] objs = {"张三","123456"};
     protected int executeUpdate(String sql,Object...paras){
         int ret = -1;

         try {
             //打开连接
             openConn();
             //获取执行SQL对象
             ps = conn.prepareStatement(sql);
             //给sql参数赋值
             if(paras != null){
                 for (int i = 0; i < paras.length; i++) {
                     ps.setObject(i+1, paras[i]);
                 }
             }

             //执行SQL
             ret = ps.executeUpdate();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally{
             //关闭资源
             closeConn();
         }

         return ret;
     }

     /**
      * 执行所有的查询
      * @param sql
      * @param paras
      */
     protected void executeQuery(String sql,Object...paras){
         try {
             //打开连接
             this.openConn();
             //获取执行SQL对象
             ps = conn.prepareStatement(sql);
             if(paras != null){
                 for (int i = 0; i < paras.length; i++) {
                     ps.setObject(i+1, paras[i]);
                 }
             }
             //执行SQL
             rs = ps.executeQuery();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }

     /**
      * 释放资源
      * @param conn
      * @param stmt
      * @param rs
      */
     protected void closeConn(){
         try {
             if(rs != null){
                 rs.close();
             }
             if(ps != null){
                 ps.close();
             }
             if(conn != null){
                 conn.close();
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }
 }