Spring中JdbcTemplate使用RowMapper

package com.cxl.demo.dao;  
  
import java.sql.ResultSet;  
import java.sql.SQLException;  
import java.util.List;  
import org.springframework.jdbc.core.JdbcTemplate;  
import org.springframework.jdbc.core.RowMapper;  
import com.cxl.demo.entity.User;  
public class UserDaoImpl {  
    private JdbcTemplate jdbcTemplate;  
  
    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {  
        this.jdbcTemplate = jdbcTemplate;  
    }  
  
    public List<User> getUserByName(String username) {  
        String sql = "select * from t_user where username = ?";  
        Object[] params = new Object[] { username };  
        List<User> users = null;  
        /** 
         * 使用接口实现类 
         */  
        users = jdbcTemplate.query(sql, params, new UserRowMapper());  
        /** 
         * 使用匿名内部类 
         * 如果UserRowMapper类只使用一次，单独为其创建一个类多余，可以使用匿名类 
         * 省略了书写一个实现类 
         */  
        users = jdbcTemplate.query(sql, params,  
                new RowMapper<User>() {  
                    @Override  
                    public User mapRow(ResultSet rs, int rowNum) throws SQLException {  
                        User user = new User();  
                        user.setId(rs.getInt("id"));  
                        user.setUsername(rs.getString("username"));  
                        user.setPassword(rs.getString("password"));  
                        return user;  
                    }  
                });  
        return (users != null && users.size() > 0) ? users : null;  
    }  
      
    public class UserRowMapper implements RowMapper<User> {  
  
        @Override  
        public User mapRow(ResultSet rs, int rowNum) throws SQLException {  
            User user = new User();  
            user.setId(rs.getInt("id"));  
            user.setUsername(rs.getString("username"));  
            user.setPassword(rs.getString("password"));  
            return user;  
        }  
          
    }  
}