java使用jdbcTemplate操作mysql数据库，遇到blob字段，正常读取出来是blob的地址，而不是blob的内容。

下面采用2中方式读取blob的内容：

1、以二进制数组形式读取blob，适用于文本数据

public void testJdbc()

	{

		ApplicationContext ctx = new ClassPathXmlApplicationContext("restlet-servlet.xml");

		JdbcTemplate jdbcTemplate = (JdbcTemplate)ctx.getBean("jdbcTemplate");

		String sql = "select * from violation_redis t where t.id < 10";

		final LobHandler lobHandler=new DefaultLobHandler();

		@SuppressWarnings("unchecked")

		List<Map<String,String>> list = jdbcTemplate.query(sql,new RowMapper(){

			public Object mapRow(ResultSet rs, int rowNum) throws SQLException

			{

				//以二进制的数组方式获得Blob数据,第二个参数3是指blob字段在结果集的位置

				byte[] attach = lobHandler.getBlobAsBytes(rs, 3);

				//非blob子弹获取

				String key = rs.getString("vio_key");

				String strAttach = new String(attach);

				p(key + "==" + strAttach);

				Map<String,String> map = new HashMap<String,String>();

				map.put("vio_key", key);

				map.put("vio_info", strAttach);

				return map;

			}

		});

		p(list);

	}

2、流模式读取blob:

public void getBlob(OutputStream  out)

{

		String sql = "select * from violation_redis t where t.id < 10";

		final LobHandler lobHandler=new DefaultLobHandler();

		List<Map<String,String>> list = jdbcTemplate.query(sql,new RowMapper(){

			public Object mapRow(ResultSet rs, int rowNum) throws SQLException

			{

				//以二进制的数组方式获得Blob数据

				InputStream is = lobHandler.getBlobAsBinaryStream(rs, 2);

				if(is != null){

				//利用spring的工具类将输入流的数据复制到输出流中

				FileCopyUtils.copy(is, out);

			}

		});

}