GeneratedKeyHolder的作用：获得新建主键值

Spring利用GeneratedKeyHolder，提供了一个可以返回新增记录对应主键值的方法： int update(PreparedStatementCreator psc, KeyHolder generatedKeyHolder)。

public Permission createPermission(final Permission permission) {  
        final String sql = "insert into sys_permissions(permission, description, available) values(?,?,?)";  
  
        GeneratedKeyHolder keyHolder = new GeneratedKeyHolder();  
        jdbcTemplate.update(new PreparedStatementCreator() {  
            @Override  
            public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {  
                PreparedStatement psst = connection.prepareStatement(sql,  new String[] { "id" });  
                psst.setString(1, permission.getPermission());  
                psst.setString(2, permission.getDescription());  
                psst.setBoolean(3, permission.getAvailable());  
                return psst;  
            }  
        }, keyHolder);  
        permission.setId(keyHolder.getKey().longValue());  
  
        return permission;  
    }

相对来说，还是很好用的。