Spring JDBCTemplate Query方法查询(转)

 近日系统有一个打印采购单的功能，发现连续打印多张后，主机宕机，看了下service和dao层的实现，很繁杂，估计原因主要出在组页面资料的时候，循环套循环导致效能下降，然后想想有什么办法可以减少组资料时的一些对象转换，dao层取回来的是map，然后还要转换成vo，然后又循环组资料，google下资料，发现jdbctemplate查询还有个query方法，可以直接在查好后返回你需要的vo，改好上线，不知道对效能有没有帮助，不过这个做法感觉不错，特把文章贴在blog里面，以备后用，呵呵


    

在内部建立内联类实现RowMapper接口

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;
  }
 }
}