最基础的java JDBC连接数据库代码并关闭连接

class Testone{

 //
 加载驱动

Connection conn = null;

PreparedStatement ps = null;

ResultSet rs = null;

         try {

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

             String url="jdbc:mysql://localhost:3306/test";

             //获得连接Connection

             try {

                 conn =DriverManager.getConnection(url,"root","123");

                 //Statement stat =conn.createStatement();

                 //ResultSet rs=stat.executeQuery("select username from user");

                 

                 String sql="select password from user where username=?";

                 String [] str={"lfxa"};

                 ps=conn.prepareStatement(sql);

                 ps.setString(1, "xiner");

                 rs=ps.executeQuery();

                 while(rs.next()){

                     System.out.println("------>"+rs.getString(1));

                     System.out.println("------>"+rs.getString("password"));

                 }

             } catch (Exception e) {

                 e.printStackTrace();

             }finally{

             
if(rs != null){

             
try{

             
rs.close();

             
rs = null;

             
}catch(Exception e){

             
e.printStackTrace();

             
}finally{

             
if(ps != null){

                     
try{

                     
ps.close();

                     
ps = null;

                     
}catch(Exception e){

                     
e.printStackTrace();

                     
}finally{

                     
if(conn != null){

                             
try{

                             
conn.close();

                             
conn = null;

                             
}catch(Exception e){

                             
e.printStackTrace();

                             
}

                             
}

                     
}

                     
}

             
}

             
}

             }

         } catch (ClassNotFoundException e) {

             e.printStackTrace();

         }

}