jdbc连接数据库工具类

package com.sff.utils;
/*
*by 落尘曦  2017.8.26
*
*/

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

public class DBconn {
//数据库连接三项			?useunicuee=true&characterEncoding=utf8   解决乱码的
static String url="jdbc:mysql://localhost:3306/test";
static String username="root";
static String password="root";
//数据库操作三项
static Connection conn=null;
static PreparedStatement ps=null; //预加载
static ResultSet rs=null; //返回的一个数据结合
static{
try {
Class.forName("com.mysql.jdbc.Driver");//加载驱动
conn = DriverManager.getConnection(url, username, password);//建立连接
} catch (ClassNotFoundException e) {
System.out.println("MySQL驱动加载异常");
e.printStackTrace();
} catch (SQLException e) {
System.out.println("数据库连接异常");
e.printStackTrace();
}
}
public static Connection getConnection(){ //获取连接
return conn;
}
public static PreparedStatement getPreparedStatement(String sql){ //获取预加载
try {
ps= conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
public static void closeConn(){
try {
conn.close();
} catch (SQLException e) {
System.out.println("数据库关闭异常");
e.printStackTrace();
}
}
public static int insertDeleteUpdate(String sql){  //增删改操作
int executeUpdate=0;
try {
ps= conn.prepareStatement(sql);
executeUpdate = ps.executeUpdate();
return executeUpdate;
} catch (SQLException e) {
System.out.println("增删改异常");
e.printStackTrace();
} finally{
try {
ps.close();
conn.close();
} catch (SQLException e) {
System.out.println("数据库关闭异常");
e.printStackTrace();
}
}
return executeUpdate;
}
public static ResultSet selectObject(String sql){
try {
ps= conn.prepareStatement(sql);
rs = ps.executeQuery();
} catch (SQLException e) {
System.out.println("查询异常");
e.printStackTrace();
}finally{
try {
rs.close();
conn.close();
} catch (SQLException e) {
System.out.println("数据库关闭异常");
e.printStackTrace();
}
}
return rs;
}
}