调用 jdbcTemplate.queryForList 时出现错误 spring-org.springframework.jdbc.IncorrectResultSetColumnCountException

查找到解决方法: http://www.cnblogs.com/wumian/articles/2012-10-25-2056.html

【推荐看看】 http://my.oschina.net/u/218421/blog/38598

调用spring jdbc接口:

User user = (User) this .jdbcTemplate.queryForObject(
                 "SELECT * FROM USER WHERE ID = 1" , User. class );

 报错如下:

Exception in thread "main"  org.springframework.jdbc.IncorrectResultSetColumnCountException: Incorrect column count: expected 1 , actual 4
     at org.springframework.jdbc.core.SingleColumnRowMapper.mapRow(SingleColumnRowMapper.java: 87 )
     at org.springframework.jdbc.core.RowMapperResultSetExtractor.extractData(RowMapperResultSetExtractor.java: 92 )
     at org.springframework.jdbc.core.RowMapperResultSetExtractor.extractData(RowMapperResultSetExtractor.java: 1 )
     at org.springframework.jdbc.core.JdbcTemplate$1QueryStatementCallback.doInStatement(JdbcTemplate.java: 445 )
     at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java: 395 )
     at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java: 455 )
     at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java: 463 )
     at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java: 471 )
     at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java: 476 )
     at com.ylp.dao.UserDao.getById(UserDao.java: 45 )
     at com.ylp.dao.Test.main(Test.java: 17 )

 大概意思是:查出的数据有4列,它把jdbc.queryForObject("SELECT * FROM USER WHERE ID = 1", User.class);中的第一列转换成User.class,所以 expected 1, actual 6,预期1列,但查出来的数据有4列

修改:

RowMapper<User> rm = ParameterizedBeanPropertyRowMapper.newInstance(User. class );
         User user = (User) this .jdbcTemplate.queryForObject(
                 "SELECT * FROM USER WHERE ID = 1" , rm);


提示:以上结论在 spring 4.x 上行不通,主要是 queryForObject 模板方法针对的结果集是“一列”的时候,并且支持的是常见类型(Integer.class)等

 再次查找资料,在官方的 api 中,仅仅提到:

elementType - the required type of element in the result list (for example, Integer.class)

哪如果我想要返回一个 List<T> 的列表对象不行吗?查找资料,发现如下文章将的比较好: 

【推荐看看】 http://my.oschina.net/u/218421/blog/38598

改用如下代码实现即可:

return (new DBUtility()).getJdbcDao().query(sql, new RowMapper<Task>() {
            public Task mapRow(ResultSet arg0, int arg1) throws SQLException {
                Task t = new Task();
                t.setTaskId(arg0.getLong("taskId"));
                t.setTaskName(arg0.getString("taskName"));
                t.setTaskDescription(arg0.getString("taskDescription"));
                t.setTaskPriority(arg0.getString("taskPriority"));
                t.setTaskStatus(arg0.getString("taskStatus"));
                return t;
            }
        });

 

OK,此时才算解决问题。

spring jdbc 版本: 4.1.1.RELEASE

你可能感兴趣的:(springframework)