usereo.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.table;

import java.sql.ResultSet;
import java.sql.SQLException;

import book.chat.DbManager;

public class UserEO {
	protected int userID;// 代表数据库中user_id列

	protected String userName;// 代表数据库中user_name列

	protected String startTime;// 代表数据库中start_time列

	public UserEO() {// 无参的构造方法
		this.userID = -1;
	}

	public UserEO(int id) {// 有参的构造方法，参数为user_id
		this.userID = id;
		if (!FromDb())// 如果有找到该id的user
			this.userID = -1;
	}

	public boolean FromDb() {// 从数据库中读出，并更新bean
		int row = -1;
		// 读记录的sql语句
		String sql = "select * from user where user_id=" + this.userID;
		ResultSet rs = DbManager.getResultSet(sql);// 执行sql语句并返回ResultSet
		try {
			rs.last();// 移动到最后一行
			row = rs.getRow();// 得到总记录数
			if (row == 1) {// 如果只查询到一条记录，则代表该记录存在并更新该类的属性
				this.userID = rs.getInt("USER_ID");
				this.userName = rs.getString("USER_NAME");
				this.startTime = rs.getString("START_TIME");
				return true;
			} else
				return false;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} finally {
			try {// 最后关闭ResutltSet,Statement.并释放连接
				if (rs != null)
					rs.close();
				if (rs.getStatement() != null)
					rs.getStatement().close();
				DbManager.releaseConnection();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	public String getStartTime() {
		return startTime;
	}

	public void setStartTime(String startTime) {
		this.startTime = startTime;
	}

	public int getUserID() {
		return userID;
	}

	public void setUserID(int userID) {
		this.userID = userID;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}
}