manager.java

jsp开发的在线答疑系统

package chatweb;
import java.sql.*;
import java.io.*;
public class manager
{
	String sDBdrive="sun.jdbc.odbc.JdbcOdbcDriver";
	String sConnStr="jdbc:odbc:chatdb";
	String user="sasa";
	String passwd="3825";
	Connection connect=null;
	ResultSet rs=null;
	public  manager()
	{
		try
		{
			Class.forName(sDBdrive).newInstance();
		}
		catch(Exception e)
		{
			System.err.println("forname:"+e.getMessage());
		}
	}
		public ResultSet executeQuery(String sql)
		{
			rs=null;
			try
			{
			connect=DriverManager.getConnection(sConnStr,user,passwd);
			Statement stmt=connect.createStatement();
			rs=stmt.executeQuery(sql);
		     }
		     catch(SQLException ex)
		     {
		     	System.err.println("SQLERROR:"+ex.getMessage());
		     }
		     return rs;
		}
	
	public boolean executeOrder(String sql)
	{
		try
			{
				connect=DriverManager.getConnection(sConnStr,user,passwd);
				Statement stmt=connect.createStatement();
				rs=stmt.executeQuery(sql);
			}	
			catch(SQLException ex)
			{
				System.err.println("executeOr:"+ex.getMessage());
				return false;//执行异常时返回false
			}
			return true;
		}
	
	public long getBlocked(String username)
	{
		ResultSet rs1=null;
		String strSQL="select *from block where username='"+username+"'";
		rs1=executeQuery(strSQL);
		try
		{
			if(rs1.next())
			{
				String strSQL2="select perio_diff(freetime,now()) as res from block where username='"+username+"';";;
			    ResultSet rs2=executeQuery(strSQL2);
			    if(rs2.next())
			    {
			    	long lefttime=rs2.getLong("res");
			    	if(lefttime<=0)
			    	{
			    		free(username);
			    		lefttime=0;
			    	}
			    	return lefttime;
			    }
			}
			
		}
		catch(Exception e)
		{
			System.err.println(e.toString());
			return -1;
			
		}
		return 0;//0与负数表示未被禁言
	}
	
	public boolean block(String username,int blocktime)
	{
		String strSQL="insertinto block values('"+username+"',date_add(now(),interval "+blocktime+" minute));";
		if(getBlocked(username)>0)
		{
			strSQL=new String("update block set freetime=date_add(now(),interval "+blocktime+" minute) where username='"+username+"';");
		}
			
		return executeOrder(strSQL);
		
	}
	
	public boolean free(String username)
	{
		String strSQL="delete from block where username='"+username+"'";
		return executeOrder(strSQL);
	}
	//删除用户
	public boolean deleteUser(String username)
	{
		if(getBlocked(username)>0)
		{
			free(username);
	 }
	 String strSQL="delete from user where username='"+username+"' and not grade=1";
	 return executeOrder(strSQL);
	}
	
	
	
	
}