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();
        }
    }
}