chatutil.java

本程序使用ajax技术实现聊天室程序.使用ajax动态获取聊天记录.

package book.chat;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Vector;

import book.chat.table.ChatEO;

public class ChatUtil {
	public static String renderChatroom() {
		Vector vResult = new Vector();//定义一个向量
		//构造查询数据库的SQL语句
		String sql = "select chat_id from chat";
		//返回记录集结果
		ResultSet rs = DbManager.getResultSet(sql);
		
		ChatEO chat;
		try {
			while (rs.next()) {//循环记录集，将结果保存到向量中
				chat = new ChatEO(rs.getInt("CHAT_ID"));
				vResult.add(chat);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		//将数据显示成HTML的格式
		StringBuffer buf = new StringBuffer();
		buf.append("<SELECT name=\"roomlist\" size=\"5\" class=\"textInput\">");
		for (int i = 0; i < vResult.size(); i++) {
			ChatEO c = (ChatEO) vResult.get(i);
			buf.append("<OPTION value=\"" + c.getChatID() + "\">"
					+ c.getChatName() + "</OPTION>");
		}
		buf.append("</SELECT>");
		//最后释放数据库连接
		DbManager.releaseConnection();
		return buf.toString();
	}
}