Java Mysql数据库工具类代码

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通过编写数据库工具类，将数据库的连接、查询、更新操作编写成特定的方法；
使用PreparedStatement语句；
传递数组形成SQL语句；

public class DBUtil {    private static Connection conn;    private static PreparedStatement ps;    private static ResultSet rs;    public static Connection getConnection(){        String Url = "jdbc:mysql://localhost:3306/smp";        String User = "root";        String Passwd = "123123";        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(Url, User, Passwd);            return conn;        } catch (ClassNotFoundException e) {            e.printStackTrace();            return null;        } catch (SQLException e) {            e.printStackTrace();            return null;        }    }    public static ResultSet excuteQuery(String sql){        if (getConnection() == null) {            return null;        }        try {            ps = conn.prepareStatement(sql);            rs = ps.executeQuery();        } catch (SQLException e) {            e.printStackTrace();        }        return rs;    }    public static ResultSet excuteQuery(String sql,Object[] obj){        if (getConnection() == null) {            return null;        }        try {            ps = conn.prepareStatement(sql);            for (int i = 0; i <obj.length ; i++) {                ps.setObject(i+1,obj[i]);            }            rs = ps.executeQuery();        } catch (SQLException e) {            e.printStackTrace();        }        return rs;    }public static int executeUpdate(String sql) {          int result = -1;          if (getConn() == null) {              return result;          }          try {              ps = conn.prepareStatement(sql);              result = ps.executeUpdate();          } catch (SQLException e) {              e.printStackTrace();          }          return result;      }      public static int excuteUpdate(String sql,Object[] obj){        int result = -1;        if (getConnection() == null) {            return 0;        }        try {            ps = conn.prepareStatement(sql);            for (int i = 0; i <obj.length ; i++) {                ps.setObject(i+1,obj[i]);            }            result = ps.executeUpdate();        } catch (SQLException e) {            e.printStackTrace();        }        return result;    }    public static void DBclose(){        try {            if (rs != null) {                rs.close();            }            if (ps != null) {                ps.close();            }            if (conn != null) {                conn.close();            }        } catch (SQLException e) {            e.printStackTrace();        }    }}

传递一个参数：

    public Student queryNumber(String number) throws SQLException{        Student stu = null;        String sql = "SELECT * from student WHERE Stu_number = ? ";        Object[] param ={number};        ResultSet rs = DBUtil.excuteQuery(sql,param);        while (rs.next()){            stu = new Student(rs.getString("Stu_name"),rs.getString("Stu_number"));            stu.setId(rs.getInt("Stu_id"));            stu.setNotes(rs.getString("Stu_notes"));            stu.setBirthday(rs.getString("Stu_birthday"));            stu.setSex(rs.getString("Stu_sex"));        }        DBUtil.DBclose();        System.out.println(stu.toString());

传递多个参数:

    public Student queryNumber(String number,String id) throws SQLException{        String sql = "SELECT * from student WHERE Stu_number = ? OR id = ?";        Object[] param ={number,id};        ResultSet rs = DBUtil.excuteQuery(sql,param);

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