DB的封裝

package com.bjsxt.bbs;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DB {
    public static Connection getConn() {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bbs", "root" , "root");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
      
    public static Statement createStmt(Connection conn) {
        Statement stmt = null;
        try {
            stmt = conn.createStatement();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return stmt;
    }
      
    public static ResultSet executeQuery(Statement stmt, String sql) {
        ResultSet rs = null;
        try {
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
      
    /*public static ResultSet executeQuery(Connection conn, String sql) {
        Statement stmt = null;
        ResultSet rs = null;
        try {
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
          
//      finally {
//          close(stmt);
//      }
          
          
        return rs;
    }*/
      
    public static int executeUpdate(Connection conn, String sql) {
        int ret = 0;
        Statement stmt = null;
        try {
            stmt = conn.createStatement();
            ret = stmt.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            close(stmt);
        }
        return ret;
    }
      
    public static PreparedStatement prepareStmt(Connection conn, String sql) {
        PreparedStatement pstmt = null;
        try {
            pstmt = conn.prepareStatement(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return pstmt;
    }
      
    public static PreparedStatement prepareStmt(Connection conn, String sql, int autoGeneratedKeys) {
        PreparedStatement pstmt = null;
        try {
            pstmt = conn.prepareStatement(sql, autoGeneratedKeys);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return pstmt;
    }
      
    public static void close(Connection conn) {
        if(conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            conn = null;
        }
    }
      
    public static void close(Statement stmt) {
        if(stmt != null) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            stmt = null;
        }
    }
      
    public static void close(ResultSet rs) {
        if(rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            rs = null;
        }
    }
}