Spring JdbcTemplate 查询方法

package hysteria.contact.dao.impl;    
   
import java.sql.ResultSet;    
import java.sql.SQLException;    
import java.sql.Types;    
import java.util.List;    
   
import org.springframework.jdbc.core.JdbcTemplate;    
import org.springframework.jdbc.core.RowMapper;    
   
import hysteria.contact.dao.ItemDAO;    
import hysteria.contact.domain.Item;    
   
public class ItemDAOImpl implements ItemDAO {    
 private JdbcTemplate jdbcTemplate;    
   
 public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {    
  this.jdbcTemplate = jdbcTemplate;    
 }    
   
 public Item insert(Item item) {    
  String sql = "INSERT INTO items(user_id,name,phone,email) VALUES(?,?,?,?)";    
  Object[] params = new Object[]{item.getUserId(),item.getName(),item.getPhone(),item.getEmail()};    
  int[] types = new int[]{Types.INTEGER,Types.VARCHAR,Types.CHAR,Types.VARCHAR};    
  jdbcTemplate.update(sql,params,types);    
  return item;    
 }    
   
 public Item update(Item item) {    
  String sql = "UPDATE items SET name = ?, phone = ?, email = ? WHERE id = ?";    
  Object[] params = new Object[] {item.getName(),item.getPhone(),item.getEmail(),item.getId()};    
  int[] types = new int[] {Types.VARCHAR,Types.CHAR,Types.VARCHAR,Types.VARCHAR,Types.INTEGER};    
  jdbcTemplate.update(sql,params,types);    
   
  return item;    
 }    
   
 public void delete(Item item) {    
  String sql = "DELETE FROM items WHERE id = ?";    
  Object[] params = new Object[] {item.getId()};    
  int[] types = new int[]{Types.INTEGER};    
  jdbcTemplate.update(sql,params,types);    
 }    
   
 public Item findById(int id) {    
  String sql = "SELECT * FROM items WHERE id = ?";    
  Object[] params = new Object[] {id};    
  int[] types = new int[] {Types.INTEGER};    
  List items = jdbcTemplate.query(sql,params,types,new ItemMapper());    
  if(items.isEmpty()){    
   return null;    
  }    
  return (Item)items.get(0);    
 }    
   
 public List<Item> findAll() {    
  String sql = "SELECT * FROM items";    
  return jdbcTemplate.query(sql,new ItemMapper());    
 }    
   
   
 public List<Item> findAllByUser(int user_id) {    
  String sql = "SELECT * FROM items WHERE user_id = ?";    
  Object[] params = new Object[]{user_id};    
  int[] types = new int[]{Types.INTEGER};    
  List items = jdbcTemplate.query(sql,params,types,new ItemMapper());    
  return items;    
 }    
   
 protected class ItemMapper implements RowMapper {    
   
  public Object mapRow(ResultSet rs, int rowNum) throws SQLException {    
   Item item = new Item();    
   item.setId(rs.getInt("id"));    
   item.setUserId(rs.getInt("user_id"));    
   item.setName(rs.getString("name"));    
   item.setPhone(rs.getString("phone"));    
   item.setEmail(rs.getString("email"));    
   
   return item;    
  }     
 }  
}