jsp 个人论坛java代码

package Bean; import java.sql.*; //定义一个类MyDB； public class MyDB { private String r="root"; private String p= "123"; private String url="jdbc:mysql://localhost/bbs"; private String driver="com.mysql.jdbc.Driver"; //查询数据库article表中的titleid最大id号用于发表主题时增加titleid号 public int queryTitleId(){ Connection conn = null; Statement stmt = null; ResultSet rs = null; int id=0; try { Class.forName(driver); conn = DriverManager.getConnection(url, "root", "123"); stmt = conn.createStatement(); rs = stmt.executeQuery("select max(titleid)from title"); while(rs.next()){ id=rs.getInt(1); } } catch (ClassNotFoundException e) { System.out.println("ClassNotFoundException!"); e.printStackTrace(); } catch (SQLException e) { System.out.println("SQLException!"); e.printStackTrace(); }finally{ try { rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return id; } //连接数据库获得最大 public int queryReplycount(int titleid){ Connection conn = null; Statement stmt = null; ResultSet rs = null; int id=0; try { Class.forName(driver); conn = DriverManager.getConnection(url, r, p); stmt = conn.createStatement(); rs = stmt.executeQuery("select max(replycounts)from title where titleid='"+titleid+"'"); while(rs.next()){ id=rs.getInt(1); } } catch (ClassNotFoundException e) { System.out.println("ClassNotFoundException!"); e.printStackTrace(); } catch (SQLException e) { System.out.println("SQLException!"); e.printStackTrace(); }finally{ try { rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return id; } //传进来一个SQL语句，将语句插入到数据库中 public void insert(String sql) { Statement stmt = null; Connection conn = null; try { Class.forName(driver); conn = DriverManager.getConnection(url, r, p); stmt= conn.createStatement(); stmt.executeUpdate(sql); } catch (ClassNotFoundException e) { System.out.println("ClassNotFoundException!"); e.printStackTrace(); } catch (SQLException e) { System.out.println("SQLException!"); e.printStackTrace(); } finally { try { stmt.close(); conn.close(); } catch (SQLException e) { System.out.println("SQLException!"); e.printStackTrace(); } } } //验证用户名和密码是否正确 public String checkUser(String username,String password) { String b = ""; Connection conn = null; Statement stmt = null; ResultSet rs = null; try { Class.forName(driver); conn = DriverManager.getConnection(url,r, p); stmt = conn.createStatement(); rs = stmt.executeQuery("select * from person where username='"+username+"'"); if (rs.next()) { if(password.equals(rs.getString(2))){ b="正确"; } else{ b="密码错误"; } } else { b ="用户不存在"; } } catch (ClassNotFoundException e) { System.out.println("类没找到"); e.printStackTrace(); } catch (SQLException e) { System.out.println("出现SQL异常"); e.printStackTrace(); } finally { try { rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return b; } //ajax中用于验证用户名是否在数据库中存在 public String checkUserName(String username) { String b = ""; Connection conn = null; Statement stmt = null; ResultSet rs = null; try { Class.forName(driver); conn = DriverManager.getConnection(url,r, p); stmt = conn.createStatement(); rs = stmt.executeQuery("select * from person where username='"+username+"'"); if (rs.next()) { b="exist"; } else { b ="unexist"; } } catch (ClassNotFoundException e) { System.out.println("类没找到"); e.printStackTrace(); } catch (SQLException e) { System.out.println("出现SQL异常"); e.printStackTrace(); } finally { try { rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return b; } public String checkEmail(String email) { String b = ""; Connection conn = null; Statement stmt = null; ResultSet rs = null; try { Class.forName(driver); conn = DriverManager.getConnection(url,r, p); stmt = conn.createStatement(); rs = stmt.executeQuery("select * from person where email='"+email+"'"); if (rs.next()) { b="exist"; } else { b ="unexist"; } } catch (ClassNotFoundException e) { System.out.println("类没找到"); e.printStackTrace(); } catch (SQLException e) { System.out.println("出现SQL异常"); e.printStackTrace(); } finally { try { rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return b; } //查询数据库结果，返回一个结果集对象 public ResultSet query(String sql){ Connection conn = null; Statement stmt = null; ResultSet rs = null; try { Class.forName(driver); conn = DriverManager.getConnection(url, r, p); stmt = conn.createStatement(); rs = stmt.executeQuery(sql); } catch (ClassNotFoundException e) { System.out.println("ClassNotFoundException!"); e.printStackTrace(); } catch (SQLException e) { System.out.println("SQLException!"); e.printStackTrace(); } return rs; } //测试用 public static void main(String[] args){ MyDB db=new MyDB(); System.out.println(db.queryTitleId()); ResultSet rs=db.query("select username ,password from person "); try { while(rs.next()) { System.out.println(rs.getString(1)); System.out.println(rs.getString(1)); System.out.println(rs.getString(2)); System.out.println(rs.getString(2)); //System.out.println(rs.getString(3)); //System.out.println(rs.getDate(4)); //System.out.println(rs.getInt(5)); //System.out.println(rs.getString(6)); //System.out.println(rs.getInt(7)); } //System.out.println("NO"); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }