JavaWeb学习-1

  1 package dao;
  2 
  3 import java.sql.Connection;
  4 import java.sql.PreparedStatement;
  5 import java.sql.ResultSet;
  6 import java.sql.SQLException;
  7 import java.util.ArrayList;
  8 import java.util.List;
  9 
 10 import Util.*;
 11 import model.*;
 12 
 13 public class UserDaoImpl implements IUserDao
 14 {
 15     @Override
 16     public void add(User user) 
 17     {
 18         Connection connection=Util.getConnection();
 19         String sql="select count(*) from t_user where username=?";
 20         PreparedStatement preparedStatement=null;
 21         ResultSet resultSet=null;
 22         try {
 23             preparedStatement=connection.prepareStatement(sql);
 24             preparedStatement.setString(1, user.getUsername());
 25             resultSet=preparedStatement.executeQuery();
 26             while(resultSet.next())
 27             {
 28                 if(resultSet.getInt(1)>0)
 29                 {
 30                     throw new UserException("用户已存在!");
 31                 }
 32             }
 33         } catch (SQLException e) {
 34             // TODO Auto-generated catch block
 35             e.printStackTrace();
 36         }
 37         sql="insert into t_user(username,password) value(?,?)";
 38         try {
 39             preparedStatement=connection.prepareStatement(sql);
 40             preparedStatement.setString(1, user.getUsername());
 41             preparedStatement.setString(2, user.getPassword());
 42             preparedStatement.executeUpdate();
 43         } catch (SQLException e) {
 44             // TODO Auto-generated catch block
 45             e.printStackTrace();
 46         }finally
 47         {
 48             Util.close(connection);
 49             Util.close(preparedStatement);
 50             Util.close(resultSet);
 51         }
 52     }
 53 
 54     @Override
 55     public void delete(String username) {
 56         Connection connection=Util.getConnection();
 57         String sql="delete from t_user where username = ?";
 58         PreparedStatement preparedStatement=null;
 59         try {
 60             preparedStatement=connection.prepareStatement(sql);
 61             preparedStatement.setString(1, username);
 62             preparedStatement.executeUpdate();
 63         } catch (SQLException e) {
 64             // TODO Auto-generated catch block
 65             e.printStackTrace();
 66         }finally
 67         {
 68             Util.close(connection);
 69             Util.close(preparedStatement);
 70         }    
 71     }
 72 
 73     @Override
 74     public void update(User user) {
 75         Connection connection=Util.getConnection();
 76         String sql="update t_user set password = ? where username = ?";
 77         PreparedStatement preparedStatement=null;
 78         try {
 79             preparedStatement=connection.prepareStatement(sql);
 80             preparedStatement.setString(1, user.getPassword());
 81             preparedStatement.setString(2, user.getUsername());
 82             preparedStatement.executeUpdate();
 83         } catch (SQLException e) {
 84             // TODO Auto-generated catch block
 85             e.printStackTrace();
 86         }finally
 87         {
 88             Util.close(connection);
 89             Util.close(preparedStatement);
 90         }
 91     }
 92 
 93     @Override
 94     public User load(int id) 
 95     {
 96         Connection connection=Util.getConnection();
 97         String sql="select * from t_user where id=?";
 98         User user=null;
 99         PreparedStatement preparedStatement=null;
100         ResultSet resultSet=null;
101         try {
102             preparedStatement=connection.prepareStatement(sql);
103             preparedStatement.setInt(1, id);
104             resultSet=preparedStatement.executeQuery();
105             while(resultSet.next())
106             {
107                 user=new User();
108                 user.setId(id);
109                 user.setUsername(resultSet.getString("username"));
110                 user.setPassword(resultSet.getString("password"));
111             }
112         } catch (SQLException e) {
113             // TODO Auto-generated catch block
114             e.printStackTrace();
115         }finally
116         {
117             Util.close(connection);
118             Util.close(preparedStatement);
119             Util.close(resultSet);
120         }
121         return user;
122     }
123 
124     @Override
125     public User load(String username) 
126     {
127         Connection connection=Util.getConnection();
128         String sql="select * from t_user where username=?";
129         User user=null;
130         PreparedStatement preparedStatement=null;
131         ResultSet resultSet=null;
132         try {
133             preparedStatement=connection.prepareStatement(sql);
134             preparedStatement.setString(1, username);
135             resultSet=preparedStatement.executeQuery();
136             while(resultSet.next())
137             {
138                 user=new User();
139                 user.setId(resultSet.getInt("id"));
140                 user.setUsername(username);
141                 user.setPassword(resultSet.getString("password"));
142             }
143         } catch (SQLException e) {
144             // TODO Auto-generated catch block
145             e.printStackTrace();
146         }finally
147         {
148             Util.close(connection);
149             Util.close(preparedStatement);
150             Util.close(resultSet);
151         }
152         return user;
153     }
154 
155     @Override
156     public List<User> load() 
157     {
158         Connection connection=Util.getConnection();
159         String sql="select * from t_user ";
160         PreparedStatement preparedStatement=null;
161         ResultSet resultSet=null;
162         List<User> users=new ArrayList<User>();
163         User user=null;
164         try
165         {
166             preparedStatement=connection.prepareStatement(sql);
167             resultSet=preparedStatement.executeQuery();
168             while(resultSet.next())
169             {
170                 user=new User();
171                 user.setId(resultSet.getInt("id"));
172                 user.setUsername(resultSet.getString("username"));
173                 user.setPassword(resultSet.getString("password"));
174                 users.add(user);
175             }
176         }catch (SQLException e) {
177             // TODO Auto-generated catch block
178             e.printStackTrace();
179         }finally
180         {
181             Util.close(connection);
182             Util.close(preparedStatement);
183             Util.close(resultSet);
184         }
185         return users;
186         }
187 }