userdao.java

servlet使用javabean源代码

package Dao;
import java.sql.*;
import java.util.*;

import Mod.*;
public class UserDao {
	private Connection con;
	private ResultSet rs;
	private Statement sql;
	public void open(){
		try{
			Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
			con=DriverManager.getConnection("jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=user","sa","");
			sql=con.createStatement();
			
				}catch(Exception e){System.out.print(e);}
	}
	public ArrayList select(UserMod user){
		
		ArrayList <UserMod>re=new ArrayList();
		String sqlline="select * from users_tab";
		if(user.getName()==""||user.getName()==null){}
		else{sqlline=sqlline+" where Name="+"'"+user.getName()+"'";}
		
		try{
			rs=sql.executeQuery(sqlline);
			int i=0;
			while(rs.next()){
				UserMod a=new UserMod();
				a.setName(rs.getString("Name"));
				
				a.setPassword(rs.getString("Password"));
				System.out.print(rs.getString("Name"));
				re.add(i++,a);
				
			}
			
		}catch(Exception e){System.out.print(e);}
		
		return re;
	}
	public String insert(UserMod user){
		String result="false";
		String sqlline="insert into users_tab values("+"'"+user.getName()+"'"+","+"'"+user.getPassword()+"')";
		try{
			sql.executeUpdate(sqlline);
			result="true";
		}catch(Exception e){System.out.print(e);}
		return result;
	}
	public String update(UserMod user,UserMod user1){
		String result="false";
		String sqlline="update users_tab set";
		if(user.getName()==null||user.getName()==""){
			if(user.getPassword()==null||user.getPassword()==""){}
			else{sqlline=sqlline+" Password='"+user.getPassword()+"'";}
		}
		else{sqlline=sqlline+" Name='"+user.getName()+"'";
		if(user.getPassword()==null||user.getPassword()==""){}else{
			sqlline=sqlline+","+"Password='"+user.getPassword()+"'";
		}}
		if(user1.getName()==null||user1.getName()==""){
			if(user1.getPassword()==null||user1.getPassword()==""){}
			else{
				sqlline=sqlline+" where Password='"+user1.getPassword()+"'";
			}
		}else{
			sqlline=sqlline+" where Name='"+user1.getName()+"'";
			if(user1.getPassword()==null||user1.getPassword()==""){}
			else{
				sqlline=sqlline+" and Password='"+user1.getPassword()+"'";
			}
		}
		try{
			System.out.print(sqlline);
			sql.executeUpdate(sqlline);
			result="true";
		}catch(Exception e){System.out.print(e);}
		return result;
		}
	public String delete(UserMod user){
		String result="false";
		
		try{
			sql.executeUpdate("delete from users_tab where Name='"+user.getName()+"'");
			result="true";
		}catch(Exception e){System.out.print(e);}
		return result;
	}
	public void close(){
		try{
	    	con.close();
	    	rs.close();
	    	sql.close();}catch(Exception e){}
	    }
}