JDBC实现增删改查

数据库帮助类DBConnection
CRUD(增删改查)每个方法中都存在加载驱动程序，获得连接对象、关闭资源对象等重复代码，DBConnection帮助类避免了代码重复，实现代码重用和面向对象中的类设计的高内聚。

public class DBConnection {
//	数据库驱动
//	MySQL版本8.0后为com.mysql.cj.jdbc.Driver
//	MySQL版本8.0前为com.mysql.jdbc.Driver
    private static final String driverName = "com.mysql.cj.jdbc.Driver";
    private static final String url = "jdbc:mysql://localhost:3306/testdb";//jdbc:mysql://localhost:端口号/数据库名
    private static final String user = "root";//数据库用户
    private static final String password = "yxj123";//数据库密码
    private DBConnection(){}
    
    //加载驱动程序
    static{
        try{
            Class.forName(driverName);
        }catch (ClassNotFoundException e){
            e.printStackTrace();
        }
    }

    //创建连接对象
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url,user,password);
    }
    
    //依次关闭资源对象
    public static void close(ResultSet rs, Statement st,Connection conn){
        try{
            if(rs!=null){
                rs.close();
            }
        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            try{
                if(st!=null){
                    st.close();
                }
            }catch (SQLException e){
                e.printStackTrace();
            }finally {
                if(conn!=null){
                    try{
                        conn.close();
                    }catch (SQLException e){
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}

CURD *** 作类StudentCURD
对Student表实现插入记录，查询记录、更新记录、删除记录的 *** 作

public class StudentCRUD {

	public static void main(String[] args) throws  ClassNotFoundException, SQLException{
		listAll();//...在该处调用方法
    }
    
    //Student(id,name,sex,age,class)
    //查询student表中的所有记录
	public static void listAll() throws SQLException{
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try{
            conn = DBConnection.getConnection();//创建连接对象
            String query="select * from student";//sql语句           
            ps=conn.prepareStatement(query);//创建prepareStatement对象执行SQl语句        
            rs=ps.executeQuery();//查询后的结果集放在rs里
            //遍历结果集对象并打印
            while (rs.next()){
                long id=rs.getInt("id");
                String name=rs.getString("name");
                String sex=rs.getString("sex");
                String age=rs.getString("age");
                String classInfo=rs.getString("class");
                System.out.println("学号："+id+";姓名："+name+";性别："+sex+";年龄："+age+";班级："+classInfo);
            }
        }finally {
            DBConnection.close(rs,ps,conn);
        }
    }

	//插入一条记录
    public static void add() throws SQLException{
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try{
            conn = DBConnection.getConnection();           
            String insert="insert into student(id,name,sex,age,class) values(?,?,?,?,?)";        
            ps=conn.prepareStatement(insert);  
            ps.setString(1,"1");
            ps.setString(2,"李四");
            ps.setString(3,"男");
            ps.setString(4,"20");
            ps.setString(5,"软件192");
            ps.executeUpdate();           
        }finally {
            DBConnection.close(rs,ps,conn);
        }
    }

	//删除一条记录
    public static void delete() throws SQLException{
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try{
            conn = DBConnection.getConnection();           
            String del="delete from student where id=?"; 
            ps=conn.prepareStatement(del);  
            ps.setString(1,"1");
            ps.executeUpdate();           
        }finally {
            DBConnection.close(rs,ps,conn);
        }
    }
    
    //更新一条记录
    public static void update() throws SQLException{
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try{
            conn = DBConnection.getConnection();           
            String update="update student set name=? where id=?";
            ps=conn.prepareStatement(update);  
            ps.setString(2,"1");
            ps.setString(1,"王五");
            ps.executeUpdate();           
        }finally {
            DBConnection.close(rs,ps,conn);
        }
    }
}

MySQL驱动jar包
官网地址：https://dev.mysql.com/downloads/connector/j/