userdao.java

mvc模式

package test.dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import test.entity.User;

public class UserDao {
	ConnectionDAL connectionDAL = new ConnectionDAL();
	Connection conn = connectionDAL.getConnection();
	Statement stmt = null;
	ResultSet rs = null;
	//查询用户名是否存在；
	public boolean select_username(User user){
		//create();
		try{
		String str="select * from fuser where username='"+
		user.getName()+"'";
		stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
		rs=stmt.executeQuery(str);
		if(rs.next()){
			return true;
		}
		else{
			return false;
	}
	}catch(Exception e){
		e.printStackTrace();
		return false;
	}finally{
		try{
			rs.close();
			stmt.close();
		}catch (Exception e) {
			e.printStackTrace();
		}
	}
	}
	//查询用户名和密码是否匹配；
	public boolean select_all(User user){
		//create();
		try{
			String str="select * from fuser where username='" +
					user.getName() +
					"' and password='" +
					user.getPassword() +
					"'";
			stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
			rs=stmt.executeQuery(str);
			if(rs.next()){
				return true;
			}
			else{
				return false;
			}
			}catch(Exception e) {
				e.printStackTrace();
				return false;
			}finally{
				try{
					rs.close();
					stmt.close();
				}catch (Exception e) {
					e.printStackTrace();
				}
			}
	}
	//新用户注册
	public boolean add(User user){
		if(select_username(user)){
			//若有该用户名存在，则不注册，直接返回false;
			return false;
		}
		try{
		String str="INSERT INTO fuser values('" +
				user.getName() +
				"','" +
				user.getPassword() +
				"')";
		stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
		conn.setAutoCommit(true);
		int i=stmt.executeUpdate(str);
		if(i==1){
			stmt.close();
			return true;
			}
		}catch(SQLException e){
			e.printStackTrace();
			return false;
		}
		return true;
		}
	//更新用户信息（数据库中操作...用user2用户信息更新user1用户信息)
	public boolean update(User user1,User user2){
		if(!select_username(user1))//若没有用户user1，则返回false;
			return false;
		try{
			String str="UPDATE fuser SET " +
					"username='"+user2.getName()+
					"' , password='"+user2.getPassword()+
					"' where username='"+user1.getName()+
					"' and 'password="+user1.getPassword()+"'";
			conn.setAutoCommit(true);
			int i=stmt.executeUpdate(str);
			if(i==1){
				return true;
			}
			else{
				return false;
			}
		}catch (Exception e) {
			e.printStackTrace();
			return false;
		}finally{
			try{
				rs.close();
				stmt.close();
			}catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
	//根据用户名删除信息
	public boolean delete(User user) {
		if(!select_all(user))//若用户名和密码不匹配，则返回false;
			return false;
		try{
			String str="delete fuser where username='"+user.getName()+"'";
			conn.setAutoCommit(true);
			int i=stmt.executeUpdate(str);
			if(i==1){
				return true;
			}
			else{
				return false;
			}
		}catch (Exception e) {
			e.printStackTrace();
			return false;
		}finally{
			try{
				rs.close();
				stmt.close();
			}catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
	public void close(){
		try{
			if(conn != null)
				conn.close();
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
}