使用SPRING 中ROWMAPPER

RowMapper可以将数据中的每一行封装成用户定义的类，在数据库查询中，如果返回的类型是用户自定义的类型则需要包装，如果是Java自定义的类型，如：String则不需要，Spring最新的类SimpleJdbcTemplate使用更加简单了。

下面这个实例说明了如何使用RowMapp，从网上下载的代码，还行能说明问题。在使用过程中我们可以将内部类做成POJO的外部类，只要实现RowMapper接口即可。如果用户想让ApplicationContext进行定义还是要谨慎。毕竟实现RowMapper接口需要给一个类增加一个mapRow方法，让类承受的功能较多，不利于分析系统。请高手多多指教。


实现一、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;

}

}

}