jdbcTemplate操作详解：增删改查实践

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"));