messagesdaoimpl.java

完整的代码

package org.fish_bone.chatting.dao;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import org.fish_bone.chatting.db.DataBaseConnection;
import org.fish_bone.chatting.vo.Messages;

/**
 *createTime:2008-9-10	下午04:13:14
 *source:http://www.taxchina.com
 *file_PATH:org.fish_bone.chatting.daoMessagesDAOImpl.java
 *project_name:jqueryChatting
 *author:lee
 */

public class MessagesDAOImpl implements MessagesDAO {

	//删除操作
	public void delete(int id) throws Exception {
		String sql = "DELETE FROM messages WHERE id=?";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;

		// 下面是针对数据库的具体操作
		try {
			// 连接数据库
			dbc = new DataBaseConnection();
			pstmt = dbc.getConnection().prepareStatement(sql);
			pstmt.setInt(1, id);
			// 进行数据库更新操作
			pstmt.executeUpdate();
			pstmt.close();
		} catch (Exception e) {
			throw new Exception("操作出现异常");
		} finally {
			// 关闭数据库连接
			dbc.close();
		}
	}

	//	 增加操作
	public void insert(Messages messages){
		String sql = "INSERT INTO messages(id,user,msg,time) VALUES(?,?,?,?)";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;
		dbc = new DataBaseConnection();
		try {
			System.out.println("id-->"+lastIdNext());
			messages.setId(lastIdNext());
			pstmt = dbc.getConnection().prepareStatement(sql);
			pstmt.setInt(1, messages.getId());
			
			pstmt.setString(2, messages.getUser());
		
			pstmt.setString(3, messages.getMsg());
		
			pstmt.setString(4, messages.getTime());
			
			pstmt.executeUpdate() ;
		
			pstmt.close();
		} catch (Exception e) {
			System.out.println("添加出错");
		} finally {
			dbc.close();
		}
	}
	/**
	 * 获得最后一个id值并加1
	 * @return
	 * @throws Exception
	 */
public int lastIdNext() throws Exception
{	int id =0 ;
List all = new ArrayList();
String sql = "SELECT id,user,msg,time FROM messages";
PreparedStatement pstmt = null;
DataBaseConnection dbc = null;

// 下面是针对数据库的具体操作
try {
	// 连接数据库
	dbc = new DataBaseConnection();
	pstmt = dbc.getConnection().prepareStatement(sql);
	// 进行数据库查询操作
	ResultSet rs = pstmt.executeQuery();
	
	while (rs.next()) {
		
		// 查询出内容，之后将查询出的内容赋值给person对象
		Messages messages = new Messages();
		messages.setId(rs.getInt(1));
		messages.setUser(rs.getString(2));
		messages.setMsg(rs.getString(3));
		messages.setTime(rs.getString(4));

		// 将查询出来的数据加入到List对象之中
		all.add(messages);	
	}
	
	if(all.size()>0)
	{System.out.println("***********8"+"---"+all.size());
		id=((Messages)(all.get(all.size()-1))).getId();
		id=id+1 ;
	}
	else{
		id=1 ;
	}
	//System.out.println(id);
	rs.close();
	pstmt.close();
} catch (Exception e) {
	throw new Exception("操作出现异常");
} finally {
	// 关闭数据库连接
	dbc.close();
}

	return id;
	}
	//查询全部
	public List queryAll() throws Exception {

		List all = new ArrayList();
		String sql = "SELECT id,user,msg,time FROM messages Order by id DESC";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;

		// 下面是针对数据库的具体操作
		try {
			// 连接数据库
			dbc = new DataBaseConnection();
			pstmt = dbc.getConnection().prepareStatement(sql);
			// 进行数据库查询操作
			ResultSet rs = pstmt.executeQuery();
			while (rs.next()) {
				// 查询出内容，之后将查询出的内容赋值给person对象
				Messages messages = new Messages();
				messages.setId(rs.getInt(1));
				messages.setUser(rs.getString(2));
				messages.setMsg(rs.getString(3));
				messages.setTime(rs.getString(4));

				// 将查询出来的数据加入到List对象之中
				all.add(messages);
			}
			rs.close();
			pstmt.close();
		} catch (Exception e) {
			throw new Exception("操作出现异常");
		} finally {
			// 关闭数据库连接
			dbc.close();
		}
		return all;
	}

	//按id查询
	public Messages queryById(int id) throws Exception {

		Messages messages = null;
		String sql = "SELECT id,user,msg,time FROM messages WHERE id=?";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;

		// 下面是针对数据库的具体操作
		try {
			// 连接数据库
			dbc = new DataBaseConnection();
			pstmt = dbc.getConnection().prepareStatement(sql);
			pstmt.setInt(1, id);
			// 进行数据库查询操作
			ResultSet rs = pstmt.executeQuery();
			if (rs.next()) {
				// 查询出内容，之后将查询出的内容赋值给messages对象
				messages = new Messages();
				messages.setId(rs.getInt(1));
				messages.setUser(rs.getString(2));
				messages.setMsg(rs.getString(3));
				messages.setTime(rs.getString(4));

			}
			rs.close();
			pstmt.close();
		} catch (Exception e) {
			throw new Exception("操作出现异常");
		} finally {
			// 关闭数据库连接
			dbc.close();
		}
		return messages;
	}

	public List queryByLike(String cond) throws Exception {

		List all = new ArrayList();
		String sql = "SELECT id,user,msg,time FROM messages WHERE user LIKE ? or msg LIKE ?";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;

		// 下面是针对数据库的具体操作
		try {
			// 连接数据库
			dbc = new DataBaseConnection();
			pstmt = dbc.getConnection().prepareStatement(sql);
			// 设置模糊查询条件
			pstmt.setString(1, "%" + cond + "%");
			pstmt.setString(2, "%" + cond + "%");
			// 进行数据库查询操作
			ResultSet rs = pstmt.executeQuery();
			while (rs.next()) {
				// 查询出内容，之后将查询出的内容赋值给person对象
				Messages messages = new Messages();
				messages.setId(rs.getInt(1));
				messages.setUser(rs.getString(2));
				messages.setMsg(rs.getString(3));
				messages.setTime(rs.getString(4));

				// 将查询出来的数据加入到List对象之中
				all.add(messages);
			}
			rs.close();
			pstmt.close();
		} catch (Exception e) {
			throw new Exception("操作出现异常");
		} finally {
			// 关闭数据库连接
			dbc.close();
		}
		return all;
	}

	// 修改操作
	public void update(Messages messages) throws Exception {
		String sql = "UPDATE messages SET user=?,msg=?,time=? WHERE id=?";
		PreparedStatement pstmt = null;
		DataBaseConnection dbc = null;

		// 下面是针对数据库的具体操作
		try {
			// 连接数据库
			dbc = new DataBaseConnection();
			pstmt = dbc.getConnection().prepareStatement(sql);
			pstmt.setString(1, messages.getUser());
			pstmt.setString(2, messages.getMsg());
			pstmt.setString(3, messages.getTime());
			pstmt.setInt(4, messages.getId());
			// 进行数据库更新操作
			pstmt.executeUpdate();
			pstmt.close();
		} catch (Exception e) {
			throw new Exception("操作出现异常");
		} finally {
			// 关闭数据库连接
			dbc.close();
		}
	}

	public static void main(String[] args) {
		Messages me = new Messages();
		me.setId(2);
		me.setMsg("ss");
		me.setTime("1");
		me.setUser("11");
		MessagesDAOImpl impl = new MessagesDAOImpl();
		try {
			impl.insert(me);
			System.out.println("chenggong");
		} catch (Exception e) {

			e.printStackTrace();
		}

	}
}