//属性

protected Connection conn;

protected PreparedStatement pstm;

protected ResultSet rs;

//方法

public void openDB(){

//1 开库

try {

Class.forName("com.mysql.jdbc.Driver");

 conn=DriverManager.

getConnection("jdbc:mysql://localhost:3306/my105","root","123456");

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

System.out.println("开错误");

}

}

public void closeDB(){

try {

if(rs!=null){

rs.close();

}

if(pstm!=null){

pstm.close();

}

if(conn!=null){

conn.close();

}

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

System.out.println("关错误");

}

}

//增删 改     INSERT INTO student( sname,age) VALUES(?,?)

//可变参数  object[]

public int myUpdate(String sql,

Object... os){

int n=0;

try {

//1 开库

openDB();

//2

pstm=conn.prepareStatement(sql);

if(os!=null){//sql有？ 

for(int i=0;i<os.length;i++){

pstm.setObject(i+1, os[i]);

}

}

//3 执行

 n=pstm.executeUpdate();

} catch (Exception e) {

// TODO: handle exception

e.printStackTrace();//一定有异常打印

}finally{

//4 必须关闭数据库

closeDB();

}

return n;

}

public ResultSet mySelect(String sql,Object... os){

try {

//1

openDB();

//2

pstm=conn.prepareStatement(sql);

if(os!=null){//sql有？ 

for(int i=0;i<os.length;i++){

pstm.setObject(i+1, os[i]);

}

}

//3 

rs=pstm.executeQuery();

} catch (Exception e) {

// TODO: handle exception

e.printStackTrace();

}finally{

//2

//closeDB();

}

return rs;

}