userbean.java

JDBC数据库高级编程源代码

package jdbcbook.msgboard;

import java.sql.*;

import jdbcbook.pub.util.*;

public class UserBean
{
	// 修改用户信息（也包括增加）
	public static boolean updateUser( UserInfo user )
	{
		if( user==null 
			|| StringUtil.isEmptyString( user.getUsername() )
			|| StringUtil.isEmptyString( user.getPassword() )
			|| StringUtil.isEmptyString( user.getEmail() ) ) return false;

		Connection conn = null;
		Statement st = null;
		try
		{
			conn 	= DatabaseBean.getConnection();
			st 		= conn.createStatement();

			// 判断用户名称是否重复
			boolean exists = false;
			String sql = "SELECT userid FROM userinfo WHERE username='" + user.getUsername() + "'";
			ResultSet rs = st.executeQuery( sql );
			while( rs.next() )
			{
				exists = ( rs.getInt( 1 ) != user.getUserID() );
			}
			rs.close();
			if( exists ) return false;

			if( user.getUserID() <= 0 )
			{
				user.setUserID( DatabaseBean.getMaxID( "userinfo" ) );
				// 增加用户信息到数据库
				sql = "INSERT INTO userinfo"
					+ "( userid, username, nickname, password, email, type, status ) "
					+ " VALUES( " + user.getUserID() + ",'" 
					+ user.getUsername() + "','" + user.getNickname() 
					+ "','" + user.getPassword() + "','"
				   	+ user.getEmail() + "'," + user.getType() + "," 
					+ user.getStatus() + " )";
			}
			else
			{
				// 修改用户信息到数据库
				sql = "UPDATE userinfo SET username='" + user.getUsername() + "', nickname='"
					+ user.getNickname() + "', password='"
					+ user.getPassword() + "', email='" + user.getEmail() + "', type="
				   	+ user.getType() + ", status=" + user.getStatus() + " WHERE userid = "
					+ user.getUserID();
			}
			int nResult = st.executeUpdate( sql );
			return nResult == 1;
		}
		catch( SQLException ex )
		{
			ex.printStackTrace( System.err );
			return false;
		}
		finally
		{
			DatabaseBean.close( null, st, conn );
		}
	}

	// 用户登录
	public static UserInfo logon( String username, String password )
	{
		Connection conn = null;
		Statement st = null;
		ResultSet rs = null;
		try
		{
			conn 	= DatabaseBean.getConnection();
			st 		= conn.createStatement();

			String sql = "SELECT userid, username, nickname, password, email, type, status "
				+ "	FROM userinfo WHERE username = '"
				+ username + "' AND password = '" + password
			   	+ "' AND status = " + UserInfo.STATUS_NORMAL;

			rs = st.executeQuery( sql );
			while( rs.next() )
			{
				UserInfo user = new UserInfo();
				user.setUserID( rs.getInt( 1 ) );
				user.setUsername( rs.getString( 2 ) );
				user.setNickname( rs.getString( 3 ) );
				user.setPassword( rs.getString( 4 ) );
				user.setEmail( rs.getString( 5 ) );
				user.setType( rs.getInt( 6 ) );
				user.setStatus( rs.getInt( 7 ) );

				return user;
			}
		}
		catch( SQLException ex )
		{
			ex.printStackTrace( System.err );
		}
		finally
		{
			DatabaseBean.close( rs, st, conn );
		}
		return null;
	}
}